This is octave-java.info, produced by makeinfo version 4.11 from octave-java.texi.  File: octave-java.info, Node: Top, Next: javaclasspath, Up: (dir) 1 Using Octave (and Matlab) with Java ************************************* This description is based on the Octave package `java-1.2.8'. The `java' package usually installs its script files (.m) in the directory `.../share/Octave/packages/java-1.2.8' and its binary (.oct) files in `.../libexec/Octave/packages/java-1.2.8'. You can get help on specific functions in Octave by executing the help command with the name of a function from this package: Octave > help javaObject You can view this help file in Octave by executing the info command with just the word java: Octave > doc java Note on calling Octave from Java ================================ The `java' package is designed for calling Java from Octave. If you want to call Octave from Java, you might want to use a library like `javaOctave' [http://kenai.com/projects/javaOctave] or `joPas' [http://jopas.sourceforge.net]. 2 Table of Contents ******************* Available Functions * Menu: * javaclasspath:: get the class path of the JVM * javaaddpath:: add a path to the class path of the JVM * javarmpath:: remove a path to the class path of the JVM * javamem:: get information about available memory * javaArray:: create a Java array * javaObject:: create a Java object * java_new:: create a Java object * javaMethod:: invoke a method on the Java object * java_invoke:: invoke a method on the Java object * java_get:: get a field on the Java object * java_set:: set a field on the Java object * javamethods:: list the available methods of a Java objects * javafields:: list the available fields of a Java objects * msgbox:: display a dialog box * errordlg:: display a dialog with an error symbol * listdlg:: display a dialog with a selection list * warndlg:: display a dialog with a warning symbol * helpdlg:: display a dialog with a help symbol * inputdlg:: display a dialog with edit fields * questdlg:: display a dialog with a question icon Frequently Asked Questions * Menu: * How to distinguish between Octave and Matlab?:: * How to make Java classes available?:: * How to create an instance of a Java class?:: * How can I handle memory limitations?:: * How to compile the java package in Octave?:: * Which TeX symbols are implemented in the dialog functions?:: 3 Available Functions *********************  File: octave-java.info, Node: javaclasspath, Next: javaaddpath, Prev: Top, Up: Top 3.1 javaclasspath ================= -- Function file: javaclasspath -- Function file: STATIC = javaclasspath -- Function file: [STATIC, DYNAMIC] = javaclasspath -- Function file: PATH = javaclasspath (WHAT) Return the class path of the Java virtual machine as a cell array of strings. If called without an input parameter: * If no output variable is given, the result is simply printed to the standard output. * If one output variable STATIC is given, the result is the static classpath. * If two output variables STATIC and DYNAMIC are given, the first variable will contain the static classpath, the second will be filled with the dynamic claspath. If called with a single input parameter WHAT: If no output parameter is given: * The result is printed to the standard output similar to the call without input parameter. If the output parameter PATH is used: * If WHAT is '-static' the static classpath is returned. * If WHAT is '-dynamic' the dynamic classpath is returned. * If WHAT is '-all' the static and the dynamic classpath are returned in a single cell array. For the example two entries have been added to the static classpath using the file `classpath.txt'. Example: Octave > javaclasspath('-all') STATIC JAVA PATH z:/someclasses.jar z:/classdir/classfiles DYNAMIC JAVA PATH - empty - Octave > javaaddpath('z:/dynamic'); Octave > ps = javaclasspath('-all') ps = { [1,1] = z:/someclasses.jar [1,2] = z:/classdir/classfiles [1,3] = z:/dynamic } *See also:* *note javaaddpath: doc-javaaddpath, *note javarmpath: doc-javarmpath, *note How to make Java classes available to Octave?: doc-FAQ.  File: octave-java.info, Node: javaaddpath, Next: javarmpath, Prev: javaclasspath, Up: Top 3.2 javaaddpath =============== -- Function File: javaaddpath (PATH) Add PATH to the dynamic class path of the Java virtual machine. PATH can be either a directory where .class files can be found, or a .jar file containing Java classes. In both cases the directory or file must exist. Example: This example adds a Java archive and a directory containing .CLASS files to the CLASSPATH and displays the current CLASSPATH list. Octave > javaaddpath('C:/java/myclasses.jar'); Octave > javaaddpath('C:/java/classes'); Octave > javaclasspath; ans = { [1,1] = C:\java\myclasses.jar [1,2] = C:\java\classes } *See also:* *note javaclasspath: doc-javaclasspath, *note javarmpath: doc-javarmpath, *note How to make Java classes available to Octave?: doc-FAQ.  File: octave-java.info, Node: javarmpath, Next: javamem, Prev: javaaddpath, Up: Top 3.3 javarmpath ============== -- Function File: javarmpath (PATH) Remove PATH from the dynamic class path of the Java virtual machine. PATH can be either a directory where .class files can be found, or a .jar file containing Java classes. Example: This example removes one of the directories added in the example for the `javaaddpath' function. Octave > javarmpath('C:/java/classes'); Octave > javaclasspath { [1,1] = C:\java\myclasses.jar } *See also:* *note javaaddpath: doc-javaaddpath, *note javaclasspath: doc-javaclasspath, *note How to make Java classes available to Octave?: doc-FAQ.  File: octave-java.info, Node: javamem, Next: javaArray, Prev: javarmpath, Up: Top 3.4 javamem =========== -- Function File: javamem -- Function File: [JMEM] = javamem Show current memory status of the java virtual machine (JVM) & run garbage collector. When no return argument is given the info is echoed to the screen. Otherwise, cell array JMEM contains MAXIMUM, TOTAL, and FREE memory (in bytes). All java-based routines are run in the JVM's shared memory pool, a dedicated and separate part of memory claimed by the JVM from your computer's total memory (which comprises physical RAM and virtual memory / swap space on hard disk). The maximum available memory can be set using the file `java.opts' (in the same subdirectory where `javaaddpath.m' lives, see `which javaaddpath'. Usually that is: [/usr]/share/Octave/packages/java-1.2.8. `java.opts' is a plain text file. It can contain memory related options, starting with `-X'. In the following exmaple, the first line specifies the initial memory size in megabytes, the second line specifies the requested maximum size: -Xms64m -Xmx512m You can adapt these values if your system has limited available physical memory. When no `java.opts' file is present, the default assignments are depending on system hardware and Java version. Typically these are an initial memory size of RAM/64 and a maximum memory size of MIN(RAM/4, 1GB), where RAM is the amount of installed memory. In the output of javamem TOTAL MEMORY is what the operating system has currently assigned to the JVM and depends on actual and active memory usage. FREE MEMORY is self-explanatory. During operation of java-based Octave functions the amounts of Total and Free memory will vary, due to java's own cleaning up and your operating system's memory management. Example: Octave > javamem Java virtual machine (JVM) memory info: Maximum available memory: 247 MB; (...running garbage collector...) OK, current status: Total memory in virtual machine: 15 MB; Free memory in virtual machine: 15 MB; 2 CPUs available. Octave > [MEM] = javamem() MEM = { [1,1] = 259522560 [2,1] = 16318464 [3,1] = 16085576 } *See also:* *note How can I handle memory limitations?: doc-FAQ.  File: octave-java.info, Node: javaArray, Next: javaObject, Prev: javamem, Up: Top 3.5 javaArray ============= -- Function File: ARRAY = javaArray (CLASS, [M, N, ...]) -- Function File: ARRAY = javaArray (CLASS, M, N, ...) Create a Java array of size `[M, N, ...]' with elements of class CLASS. CLASS can be a Java object representing a class or a string containing the fully qualified class name. The generated array is uninitialized, all elements are set to null if CLASS is a reference type, or to a default value (usually 0) if CLASS is a primitive type. Example: This example creates a (2 x 2) array of Java STRING objects and assigns a value to one of the elements. Finally it displays the type of A. Octave > a = javaArray('java.lang.String', 2, 2); Octave > a(1,1) = 'Hello'; Octave > a a =  File: octave-java.info, Node: javaObject, Next: java_new, Prev: javaArray, Up: Top 3.6 javaObject ============== -- Function File: OBJECT = javaObject (CLASS, [ARG1, ..., ARGN]) Create a Java object of class CLASS, by calling the class constructor with the given arguments ARG1, ..., ARGN. The CLASS name should be given in fully qualified string form (including any package prefix). In Matlab you should avoid to use the import statement and the short form of object creation. Example: This example demonstrates two ways to create a Java `StringBuffer' object. The first variant creates an uninitialized STRINGBUFFER object, while the second variant calls a constructor with the given initial `String'. Then it displays the type of `o', and finally the content of the `StringBuffer' object is displayed by using its `toString' method. Octave > o = javaObject('java.lang.StringBuffer'); Octave > o = javaObject('java.lang.StringBuffer', 'Initial'); Octave > o o = Octave > o.toString ans = Initial Equivalent to the `java_new' function. For compatibility with Matlab it is recommended to use the `javaObject' function. *See also:* *note java_new: doc-java_new.  File: octave-java.info, Node: java_new, Next: javaMethod, Prev: javaObject, Up: Top 3.7 java_new ============ -- Function File: OBJECT = java_new (CLASS, [ARG1, ..., ARGN]) Create a Java object of class CLASS, by calling the class constructor with the given arguments ARG1, ..., ARGN. Equivalent to the `javaObject' function. For compatibility with Matlab it is recommended to use the `javaObject' function. Example: Octave > o = java_new('java.lang.StringBuffer', 'Initial'); Octave > o o = Octave > o.toString ans = Initial *See also:* *note javaObject: doc-javaObject.  File: octave-java.info, Node: javaMethod, Next: java_invoke, Prev: java_new, Up: Top 3.8 javaMethod ============== -- Function File: RET = javaMethod (NAME, OBJECT[, ARG1, ..., ARGN]) Invoke the method NAME on the Java object OBJECT with the arguments ARG1, ... For static methods, OBJECT can be a string representing the fully qualified name of the corresponding class. The function returns the result of the method invocation. When OBJECT is a regular Java object, the structure-like indexing can be used as a shortcut syntax. For instance, the two statements in the example are equivalent. Example: Octave > ret = javaMethod("method1", x, 1.0, "a string") Octave > ret = x.method1(1.0, "a string") *See also:* *note javamethods: doc-javamethods.  File: octave-java.info, Node: java_invoke, Next: java_get, Prev: javaMethod, Up: Top 3.9 java_invoke =============== -- Function File: RET = java_invoke (OBJECT, NAME[, ARG1, ..., ARGN]) Invoke the method NAME on the Java object OBJECT with the arguments ARG1, ... For static methods, OBJECT can be a string representing the fully qualified name of the corresponding class. The function returns the result of the method invocation. Equivalent to the `javaMethod' function. When OBJECT is a regular Java object, the structure-like indexing can be used as a shortcut syntax. For instance, the two statements in the example are equivalent. Example: Octave > ret = java_invoke(x, "method1", 1.0, "a string") Octave > ret = x.method1(1.0, "a string") *See also:* *note javamethods: doc-javamethods.  File: octave-java.info, Node: java_get, Next: java_set, Prev: java_invoke, Up: Top 3.10 java_get ============= -- Function File: VAL = java_get (OBJECT, NAME) Get the value of the field NAME of the Java object OBJECT. For static fields, OBJECT can be a string representing the fully qualified name of the corresponding class. When OBJECT is a regular Java object, the structure-like indexing can be used as a shortcut syntax. For instance, the two statements in the example are equivalent Example: Octave > java_get(x, "field1") Octave > x.field1 *See also:* *note javafields: doc-javafields, *note java_set: doc-java_set.  File: octave-java.info, Node: java_set, Next: javamethods, Prev: java_get, Up: Top 3.11 java_set ============= -- Function File: OBJECT = java_set (OBJECT, NAME, VALUE) Set the value of the field NAME of the Java object OBJECT to VALUE. For static fields, OBJECT can be a string representing the fully qualified named of the corresponding Java class. When OBJECT is a regular Java object, the structure-like indexing can be used as a shortcut syntax. For instance, the two statements in the example are equivalent Example: Octave > java_set(x, "field1", val) Octave > x.field1 = val *See also:* *note javafields: doc-javafields, *note java_get: doc-java_get.  File: octave-java.info, Node: javamethods, Next: javafields, Prev: java_set, Up: Top 3.12 javamethods ================ -- Function File: M = javamethods (CLASSNAME) -- Function File: M = javamethods (OBJECT) Given a string with a Java class name CLASSNAME or a regular Java object OBJECT, this function returns a cell array containing descriptions of all methods of the Java class CLASSNAME respectively the class of OBJECT. Examples: The first example shows how the methods of a class can be queried, while the second example works with the methods of a concrete instance of a class. Note that creation of a `java.lang.Double' object requires an initializer (in the example the value 1.2). Octave > m = javamethods('java.lang.Double'); Octave > size(m) ans = 1 30 Octave > m{7} ans = double longBitsToDouble(long) Octave > o = javaObject('java.lang.Double', 1.2); Octave > m = javamethods(o); Octave > size(m) ans = 1 30 Octave > m{7} ans = double longBitsToDouble(long) *See also:* *note javafields: doc-javafields, *note java_invoke: doc-java_invoke.  File: octave-java.info, Node: javafields, Next: msgbox, Prev: javamethods, Up: Top 3.13 javafields =============== -- Function File: F = javafields (CLASSNAME) -- Function File: F = javafields (OBJECT) Given a string with a Java class name CLASSNAME or a regular Java object OBJECT, this function returns a cell array containing the descriptions for all fields of the Java class CLASSNAME respectively the class of OBJECT. Examples: The first example shows how the fields of a class can be queried without creating an instance of the class. Octave > f = javafields('java.lang.Double'); Octave > size(f) ans = 1 10 Octave > f{7} ans = public static final int java.lang.Double.MAX_EXPONENT The second example works with the fields of an instance of a class. Note that creation of a `java.lang.Double' object requires an initializer (in the example a value of 1.2 is specified). Octave > o = javaObject('java.lang.Double', 1.2); Octave > f = javafields(o); Octave > size(f) ans = 1 10 Octave > f{7} ans = public static final int java.lang.Double.MAX_EXPONENT *See also:* *note java_set: doc-java_set, *note java_get: doc-java_get.  File: octave-java.info, Node: msgbox, Next: errordlg, Prev: javafields, Up: Top 3.14 msgbox =========== -- Function File: F = msgbox (MESSAGE) -- Function File: F = msgbox (MESSAGE, TITLE) -- Function File: F = msgbox (MESSAGE, TITLE, ICON) Displays a MESSAGE using a dialog box. The parameter TITLE can be used to optionally decorate the dialog caption. The third optional parameter ICON can be either `'error'', `'help'' or `'warn'' and selectes the corresponding icon. If it is omitted, no icon is shown. Examples: The first example shows a dialog box without a caption text, whereas the second example specifies a caption text of its own. The third example also demonstrates how a character according to the TeX symbol set can be specified. It is important to include a space character after the symbol code and how to embed a newline character (ASCII code 10) into the string. Octave > msgbox('This is an important message'); Octave > msgbox('Do not forget to feed the cat.', 'Remember'); Octave > msgbox(['I \heartsuit Octave!',10, ... ' Even if I hate it sometimes.'], ... 'I Confess','warn'); [image src="images/image003.png"] *See also:* *note errordlg: doc-errordlg, *note helpdlg: doc-helpdlg, *note warndlg: doc-warndlg.  File: octave-java.info, Node: errordlg, Next: helpdlg, Prev: msgbox, Up: Top 3.15 errordlg ============= -- Function File: F = errordlg (MESSAGE) -- Function File: F = errordlg (MESSAGE, TITLE) Displays the MESSAGE using an error dialog box. The TITLE can be used optionally to decorate the dialog caption instead of the default title "Error Dialog". Examples: The first example shows a dialog box with default caption, whereas the second example specifies a its own caption Octave > errordlg('Oops, an expected error occured'); [image src="images/image001.png"] Octave > errordlg('Another error occured', 'Oops'); *See also:* *note helpdlg: doc-helpdlg, *note inputdlg: doc-inputdlg, *note listdlg: doc-listdlg, *note questdlg: doc-questdlg, *note warndlg: doc-warndlg.  File: octave-java.info, Node: helpdlg, Next: inputdlg, Prev: errordlg, Up: Top 3.16 helpdlg ============ -- Function File: F = helpdlg (MESSAGE) -- Function File: F = helpdlg (MESSAGE, TITLE) Displays the MESSAGE using a help dialog box. The help message can consist of multiple lines, separated by a newline character. The TITLE can be used optionally to decorate the dialog caption bar instead of the default title "Help Dialog". Examples: The first example shows a dialog box with default caption, whereas the next two examples specify their own caption. Note that if the backslash escape notation is used in a double quoted string, it is immediately replaced by Octave with a newline. If it is contained in a single quoted string, it is not replaced by Octave, but later by the dialog function. Octave > helpdlg('This is a short notice'); Octave > helpdlg(['line #1',10,'line #2'], 'Inventory'); Octave > helpdlg("1 eel\n9 buckazoids\n2 peas", 'Inventory'); [image src="images/image004.png"] *See also:* *note errordlg: doc-errordlg, *note inputdlg: doc-inputdlg, *note listdlg: doc-listdlg, *note questdlg: doc-questdlg, *note warndlg: doc-warndlg.  File: octave-java.info, Node: inputdlg, Next: listdlg, Prev: helpdlg, Up: Top 3.17 inputdlg ============= -- Function File: C = inputdlg (PROMPT) -- Function File: C = inputdlg (PROMPT, TITLE) -- Function File: C = inputdlg (PROMPT, TITLE, ROWSCOLS) -- Function File: C = inputdlg (PROMPT, TITLE, ROWSCOLS, DEFAULTS) Returns the user's inputs from a multi-textfield dialog box in form of a cell array of strings. If the user closed the dialog with the Cancel button, en empty cell array is returned. This can be checked with the ISEMPTY function. The first argument PROMPT is mandatory. It is a cell array with strings labeling each text field. The optional string TITLE can be used as the caption of the dialog. The size of the text fields can be defined by the argument ROWSCOLS, which can be either a scalar to define the number of columns used for each text field, a vector to define the number of rows for each text field individually, or a matrix to define the number of rows and columns for each text field individually. It is possible to place default values into the text fields by supplying a cell array of strings for the argument DEFAULTS. Examples: The first example shows a simple usage of the input dialog box without defaults. Octave > prompt = {'Width','Height','Depth'}; Octave > dims = inputdlg(prompt, 'Enter Box Dimensions'); Octave > volume = str2num(dims{1}) * ... str2num(dims{2}) * str2num(dims{3}); [image src="images/image005.png"] The second example shows the application of a scalar for the number of rows and a cell array with default values. Octave > prompt = {'Width', 'Height', 'Depth'}; Octave > defaults = {'1.1', '2.2', '3.3'}; Octave > title = 'Enter Box Dimensions'; Octave > dims = inputdlg(prompt, title, 1, defaults); Octave > dims dims = { [1,1] = 1.1 [2,1] = 2.2 [3,1] = 3.3 } [image src="images/image006.png"] The third example shows the application of row height and column width specification.. Octave > prompt = {'Width', 'Height', 'Depth'}; Octave > defaults = {'1.1', '2.2', '3.3'}; Octave > rc = [1,10; 2,20; 3,30]; Octave > title = 'Enter Box Dimensions'; Octave > dims = inputdlg(prompt, title, rc, defaults); [image src="images/image007.png"] *See also:* *note errordlg: doc-errordlg, *note helpdlg: doc-helpdlg, *note listdlg: doc-listdlg, *note questdlg: doc-questdlg, *note warndlg: doc-warndlg.  File: octave-java.info, Node: listdlg, Next: questdlg, Prev: inputdlg, Up: Top 3.18 listdlg ============ -- Function File: [SEL, OK] = listdlg (KEY, VALUE[, KEY, VALUE, ...]) This function returns the inputs from a list dialog box. The result is returned as a vector of indices and a flag. The vector SEL contains the 1-based indices of all list items selected by the user. The flag OK is 1 if the user closed the dialog with the OK Button, otherwise it is 0 and SEL is empty.. The arguments of this function are specified in the form of KEY, VALUE pairs. At least the `'ListString'' argument pair must be specified. It is also possible to preselect items in the list in order to provide a default selection. The KEY and VALUE pairs can be selected from the following list: `ListString' a cell array of strings comprising the content of the list. `SelectionMode' can be either `'single'' or `'multiple''. `ListSize' a vector with two elements `[width, height]' defining the size of the list field in pixels. `InitialValue' a vector containing 1-based indices of preselected elements. `Name' a string to be used as the dialog caption. `PromptString' a cell array of strings to be displayed above the list field. `OKString' a string used to label the OK button. `CancelString' a string used to label the Cancel button. Example: Octave > [s,ok] = listdlg('ListString', ... {'An item', 'another', 'yet another'}, ... 'Name', 'Selection Dialog', ... 'SelectionMode', 'Multiple', ... 'PromptString',['Select an item...',10,'...or multiple items']); Octave > imax = length(s); Octave > for i=1:1:imax Octave > disp(s(i)); Octave > end [image src="images/image002.png"] *See also:* *note errordlg: doc-errordlg, *note helpdlg: doc-helpdlg, *note inputdlg: doc-inputdlg, *note questdlg: doc-questdlg, *note warndlg: doc-warndlg.  File: octave-java.info, Node: questdlg, Next: warndlg, Prev: listdlg, Up: Top 3.19 questdlg ============= -- Function File: C = questdlg (MESSAGE, TITLE) -- Function File: C = questdlg (MESSAGE, TITLE, DEFAULT) -- Function File: C = questdlg (MESSAGE, TITLE, BTN1, BTN2, DEFAULT) -- Function File: C = questdlg (MESSAGE, TITLE, BTN1, BTN2, BTN3, DEFAULT) Displays the MESSAGE using a question dialog box with a caption TITLE. The dialog contains two or three buttons which all close the dialog. It returns the caption of the activated button. If only MESSAGE and TITLE are specified, three buttons with the default captions "Yes", "No", "Cancel" are used. The string DEFAULT identifies the default button, which is activated by pressing the ENTER key. It must match one of the strings given in BTN1, BTN2 or BTN3. If only two button captions BTN1 and BTN2 are specified, the dialog will have only these two buttons. Examples: The first example shows a dialog box with two buttons, whereas the next example demonstrates the use of three buttons. Octave > questdlg('Select your gender', 'Sex', ... 'Male', 'Female', 'Female'); [image src="images/image008.png"] Octave > questdlg('Select your gender', 'Sex', ... 'Male', 'dont know', 'Female', 'Female'); [image src="images/image009.png"] *See also:* *note errordlg: doc-errordlg, *note helpdlg: doc-helpdlg, *note inputdlg: doc-inputdlg, *note listdlg: doc-listdlg, *note warndlg: doc-warndlg.  File: octave-java.info, Node: warndlg, Next: How to distinguish between Octave and Matlab?, Prev: questdlg, Up: Top 3.20 warndlg ============ -- Function File: F = warndlg (MESSAGE) -- Function File: F = warndlg (MESSAGE, TITLE) Displays a MESSAGE using a warning dialog box. The TITLE can be used optionally to decorate the dialog caption instead of the default title "Warning Dialog". Examples: The first example shows a dialog box with default caption, whereas the second example specifies a caption text of its own. The second example also demonstrates how a character according to the TeX symbol set can be specified. It is important to include a space character after the symbol code. The \n character can be used to start a new line. The third example shows an alternate way to embed the newline character (the newline character has the ASCII code 10) into the string. Please refer to the Octave manual for the difference between single and double quoted strings. Octave > warndlg('An expected warning occured'); Octave > warndlg('I \heartsuit Octave!\nEven if I hate her sometimes.', ... 'Confession'); Octave > warndlg(['I \heartsuit Octave!',10, ... ' Even if I hate her sometimes.'], ... 'I Confess'); [image src="images/image003.png"] *See also:* *note errordlg: doc-errordlg, *note helpdlg: doc-helpdlg, *note inputdlg: doc-inputdlg, *note listdlg: doc-listdlg, *note questdlg: doc-questdlg. 4 FAQ - Frequently asked Questions **********************************  File: octave-java.info, Node: How to distinguish between Octave and Matlab?, Next: How to make Java classes available?, Prev: warndlg, Up: Top 4.1 How to distinguish between Octave and Matlab? ================================================= Octave and Matlab are very similar, but handle Java slightly different. Therefore it may be necessary to detect the environment and use the appropriate functions. The following function can be used to detect the environment. Due to the persistent variable it can be called repeatedly without a heavy performance hit. Example: %% %% Return: true if the environment is Octave. %% function ret = isOctave persistent retval; % speeds up repeated calls if isempty(retval) retval = (exist('Octave_VERSION','builtin') > 0); end ret = retval; end  File: octave-java.info, Node: How to make Java classes available?, Next: How to create an instance of a Java class?, Prev: How to distinguish between Octave and Matlab?, Up: Top 4.2 How to make Java classes available to Octave? ================================================= Java finds classes by searching a CLASSPATH. This is a list of Java archive files and/or directories containing class files. In Octave and Matlab the CLASSPATH is composed of two parts: * the STATIC CLASSPATH is initialized once at startup of the JVM, and * the DYNAMIC CLASSPATH which can be modified at runtime. Octave searches the STATIC CLASSPATH first, then the DYNAMIC CLASSPATH. Classes appearing in the STATIC as well as in the DYNAMIC CLASSPATH will therefore be found in the STATIC CLASSPATH and loaded from this location. Classes which shall be used regularly or must be available to all users should be added to the STATIC CLASSPATH. The STATIC CLASSPATH is populated once from the contents of a plain text file named `classpath.txt' when the Java Virtual Machine starts. This file contains one line for each individual classpath to be added to the STATIC CLASSPATH. These lines can identify single class files, directories containing class files or Java archives with complete class file hierarchies. Comment lines starting with a `#' or a `%' character are ignored. The search rules for the file `classpath.txt' are: * First, Octave searches for the file `classpath.txt' in your home directory, If such a file is found, it is read and defines the initial STATIC CLASSPATH. Thus it is possible to build an initial static classpath on a 'per user' basis. * Next, Octave looks for another file `classpath.txt' in the package installation directory. This is where `javaclasspath.m' resides, usually something like `...\share\Octave\packages\java-1.2.8'. You can find this directory by executing the command pkg list If this file exists, its contents is also appended to the static classpath. Note that the archives and class directories defined in this file will affect all users. Classes which are used only by a specific script should be placed in the DYNAMIC CLASSPATH. This portion of the classpath can be modified at runtime using the `javaaddpath' and `javarmpath' functions. Example: Octave > base_path = 'C:/Octave/java_files'; Octave > % add two JARchives to the dynamic classpath Octave > javaaddpath([base_path, '/someclasses.jar']); Octave > javaaddpath([base_path, '/moreclasses.jar']); Octave > % check the dynamic classpath Octave > p = javaclasspath; Octave > disp(p{1}); C:/Octave/java_files/someclasses.jar Octave > disp(p{2}); C:/Octave/java_files/moreclasses.jar Octave > % remove the first element from the classpath Octave > javarmpath([base_path, '/someclasses.jar']); Octave > p = javaclasspath; Octave > disp(p{1}); C:/Octave/java_files/moreclasses.jar Octave > % provoke an error Octave > disp(p{2}); error: A(I): Index exceeds matrix dimension. Another way to add files to the DYNAMIC CLASSPATH exclusively for your user account is to use the file `.octaverc' which is stored in your home directory. All Octave commands in this file are executed each time you start a new instance of Octave. The following example adds the directory `octave' to Octave's search path and the archive `myclasses.jar' in this directory to the Java search path. % content of .octaverc: addpath('~/octave'); javaaddpath('~/octave/myclasses.jar');  File: octave-java.info, Node: How to create an instance of a Java class?, Next: How can I handle memory limitations?, Prev: How to make Java classes available?, Up: Top 4.3 How to create an instance of a Java class? ============================================== If your code shall work under Octave as well as Matlab you should use the function `javaObject' to create Java objects. The function `java_new' is Octave specific and does not exist in the Matlab environment. Example 1, suitable for Octave but not for Matlab: Passenger = java_new('package.FirstClass', row, seat); Example 2, which works in Octave as well as in Matlab: Passenger = javaObject('package.FirstClass', row, seat);  File: octave-java.info, Node: How can I handle memory limitations?, Next: How to compile the java package in Octave?, Prev: How to create an instance of a Java class?, Up: Top 4.4 How can I handle memory limitations? ======================================== In order to execute Java code Octave creates a Java Virtual Machine (JVM). Such a JVM allocates a fixed amount of initial memory and may expand this pool up to a fixed maximum memory limit. The default values depend on the Java version (see *note javamem: doc-javamem.). The memory pool is shared by all Java objects running in the JVM. This strict memory limit is intended mainly to avoid that runaway applications inside web browsers or in enterprise servers can consume all memory and crash the system. When the maximum memory limit is hit, Java code will throw exceptions so that applications will fail or behave unexpectedly. In Octave as well as in Matlab, you can specify options for the creation of the JVM inside a file named `java.opts'. This is a text file where you can enter lines containing `-X' and `-D' options handed to the JVM during initialization. In Octave, the Java options file must be located in the directory where `javaclasspath.m' resides, i.e. the package installation directory, usually something like ...\SHARE\OCTAVE\PACKAGES\JAVA-1.2.8. You can find this directory by executing pkg list In Matlab, the options file goes into the MATLABROOT/BIN/ARCH directory or in your personal Matlab startup directory (can be determined by a `pwd' command). MATLABROOT is the Matlab root directory and ARCH is your system architecture, which you find by issuing the commands `matlabroot' respectively `computer('arch')'. The `-X' options allow you to increase the maximum amount of memory available to the JVM to 256 Megabytes by adding the following line to the `java.opts' file: -Xmx256m The maximum possible amount of memory depends on your system. On a Windows system with 2 Gigabytes main memory you should be able to set this maximum to about 1 Gigabyte. If your application requires a large amount of memory from the beginning, you can also specify the initial amount of memory allocated to the JVM. Adding the following line to the `java.opts' file starts the JVM with 64 Megabytes of initial memory: -Xms64m For more details on the available `-X' options of your Java Virtual Machine issue the command `java -X' at the operating system command prompt and consult the Java documentation. The `-D' options can be used to define system properties which can then be used by Java classes inside Octave. System properties can be retrieved by using the `getProperty()' methods of the `java.lang.System' class. The following example line defines the property MYPROPERTY and assigns it the string `12.34'. -DMyProperty=12.34 The value of this property can then be retrieved as a string by a Java object or in Octave: Octave > javaMethod('java.lang.System', 'getProperty', 'MyProperty'); ans = 12.34 *See also:* *note javamem: doc-javamem.  File: octave-java.info, Node: How to compile the java package in Octave?, Next: Which TeX symbols are implemented in the dialog functions?, Prev: How can I handle memory limitations?, Up: Top 4.5 How to compile the java package in Octave? ============================================== Most Octave installations come with the JAVA package pre-installed. In case you want to replace this package with a more recent version, you must perform the following steps: 4.5.1 Uninstall the currently installed package JAVA ---------------------------------------------------- Check whether the JAVA package is already installed by issuing the `pkg list' command: Octave > pkg list Package Name | Version | Installation directory --------------+---------+----------------------- java *| 1.2.8 | /home/octavio/octave/java-1.2.8 Octave > If the JAVA package appears in the list you must uninstall it first by issuing the command Octave > pkg uninstall java Octave > pkg list Now the java package should not be listed anymore. If you have used the JAVA package during the current session of Octave, you have to exit and restart Octave before you can uninstall the package. This is because the system keeps certain libraries in memory after they have been loaded once. 4.5.2 Make sure that the build environment is configured properly ----------------------------------------------------------------- The installation process requires that the environment variable `JAVA_HOME' points to the Java Development Kit (JDK) on your computer. * Note that JDK is not equal to JRE (Java Runtime Environment). The JDK home directory contains subdirectories with include, library and executable files which are required to compile the JAVA package. These files are not part of the JRE, so you definitely need the JDK. * Do not use backslashes but ordinary slashes in the path. Set the environment variable `JAVA_HOME' according to your local JDK installation. Please adapt the path in the following examples according to the JDK installation on your system. If you are using a Windows system that might be: Octave > setenv("JAVA_HOME","C:/Java/jdk1.6.0_21"); Note, that on both system types, Windows as well as Linux, you must use the forward slash '/' as the separator, not the backslash '\'. If you are using a Linux system this would look probably more like: Octave > setenv("JAVA_HOME","/usr/local/jdk1.6.0_21"); 4.5.3 Compile and install the package in Octave ----------------------------------------------- If you have for example saved the package archive on your Z: drive the command would be: Octave> pkg install -verbose z:/java-1.2.8.tar.gz or if you have Linux and the package file is stored in your home directory: Octave > pkg install -verbose ~/java-1.2.8.tar.gz The option `-verbose' will produce some lengthy output, which should not show any errors (maybe a few warnings at best). You can then produce a list of all installed packages: Octave > pkg list This list of packages should now include the package JAVA: Octave > pkg list Package Name | Version | Installation directory --------------+---------+----------------------- java *| 1.2.8 | /home/octavio/octave/java-1.2.8 Octave > 4.5.4 Test the java package installation ---------------------------------------- The following code creates a Java string object, which however is automatically converted to an Octave string: Octave > s = javaObject('java.lang.String', 'Hello OctaveString') s = Hello OctaveString Note that the java package automatically transforms the Java String object to an Octave string. This means that you cannot apply Java String methods to the result. This "auto boxing" scheme seems to be implemented for the following Java classes: * java.lang.Integer * java.lang.Double * java.lang.Boolean * java.lang.String If you instead create an object for which no "auto-boxing" is implemented, `javaObject' returns the genuine Java object: Octave > v = javaObject('java.util.Vector') v = Octave > v.add(12); Octave > v.get(0) ans = 12 If you have created such a Java object, you can apply all methods of the Java class to the returned object. Note also that for some objects you must specify an initializer: % not: Octave > d = javaObject('java.lang.Double') error: [java] java.lang.NoSuchMethodException: java.lang.Double % but: Octave > d = javaObject('java.lang.Double',12.34) d = 12.340  File: octave-java.info, Node: Which TeX symbols are implemented in the dialog functions?, Prev: How to compile the java package in Octave?, Up: Top 4.6 Which TeX symbols are implemented in the dialog functions? ============================================================== The dialog functions contain a translation table for TeX like symbol codes. Thus messages and labels can be tailored to show some common mathematical symbols or Greek characters. No further TeX formatting codes are supported. The characters are translated to their Unicode equivalent. However, not all characters may be displayable on your system. This depends on the font used by the Java system on your computer. Each TeX symbol code must be terminated by a space character to make it distinguishable from the surrounding text. Therefore the string `\alpha =12.0' will produce the desired result, whereas `\alpha=12.0' would produce the literal text '\ALPHA=12.0'. *See also:* *note errordlg: doc-errordlg, *note helpdlg: doc-helpdlg, *note inputdlg: doc-inputdlg, *note listdlg: doc-listdlg, *note msgbox: doc-msgbox, *note questdlg: doc-questdlg, *note warndlg: doc-warndlg. Index ===== [index] * Menu: * array, creating a Java array: javaArray. (line 6) * available functions: Top. (line 29) * calling Java from Octave: Top. (line 6) * calling Octave from Java: Top. (line 16) * classes, making available to Octave: How to make Java classes available?. (line 6) * classpath, adding new path: javaaddpath. (line 6) * classpath, difference between static and dynamic: How to make Java classes available?. (line 6) * classpath, displaying: javaclasspath. (line 8) * classpath, dynamic <1>: javaaddpath. (line 6) * classpath, dynamic: javaclasspath. (line 8) * classpath, removing path: javarmpath. (line 6) * classpath, setting: How to make Java classes available?. (line 6) * classpath, static: javaclasspath. (line 8) * classpath.txt: How to make Java classes available?. (line 6) * compiling the java package, how?: How to compile the java package in Octave?. (line 6) * dialog, displaying a help dialog: helpdlg. (line 6) * dialog, displaying a list dialog: listdlg. (line 6) * dialog, displaying a question dialog: questdlg. (line 6) * dialog, displaying a warning dialog <1>: warndlg. (line 6) * dialog, displaying a warning dialog: msgbox. (line 6) * dialog, displaying an error dialog: errordlg. (line 6) * dialog, displaying an input dialog: inputdlg. (line 6) * dynamic classpath <1>: How to make Java classes available?. (line 6) * dynamic classpath: javaclasspath. (line 8) * dynamic classpath, adding new path: javaaddpath. (line 6) * field, returning value of Java object field: java_get. (line 6) * field, setting value of Java object field: java_set. (line 6) * fields, displaying available fields of a Java object: javafields. (line 6) * functions, available in the package java: Top. (line 29) * instance, how to create: How to create an instance of a Java class?. (line 6) * java package, how to compile?: How to compile the java package in Octave?. (line 6) * java package, how to install?: How to compile the java package in Octave?. (line 6) * java package, how to uninstall?: How to compile the java package in Octave?. (line 6) * Java, calling from Octave: Top. (line 6) * Java, using with Octave: Top. (line 6) * memory, displaying Java memory status: javamem. (line 6) * memory, limitations: How can I handle memory limitations?. (line 6) * method, invoking a method of a Java object <1>: java_invoke. (line 6) * method, invoking a method of a Java object: javaMethod. (line 6) * methods, displaying available methods of a Java object: javamethods. (line 6) * object, creating a Java object <1>: java_new. (line 6) * object, creating a Java object: javaObject. (line 6) * object, how to create: How to create an instance of a Java class?. (line 6) * Octave and Matlab, how to distinguish between: How to distinguish between Octave and Matlab?. (line 6) * Octave, calling from Java: Top. (line 16) * package java, available functions: Top. (line 29) * package, how to compile?: How to compile the java package in Octave?. (line 6) * path, adding to classpath: javaaddpath. (line 6) * path, removing from classpath: javarmpath. (line 6) * static classpath <1>: How to make Java classes available?. (line 6) * static classpath: javaclasspath. (line 8) * symbols, translation table: Which TeX symbols are implemented in the dialog functions?. (line 6) * TeX symbols, translation table: Which TeX symbols are implemented in the dialog functions?. (line 6) * translation table for TeX symbols: Which TeX symbols are implemented in the dialog functions?. (line 6) * using Octave with Java: Top. (line 6)  Tag Table: Node: Top87 Node: javaclasspath2609 Ref: doc-javaclasspath2739 Node: javaaddpath4789 Ref: doc-javaaddpath4919 Node: javarmpath5818 Ref: doc-javarmpath5940 Node: javamem6642 Ref: doc-javamem6756 Node: javaArray9286 Ref: doc-javaArray9404 Node: javaObject10242 Ref: doc-javaObject10363 Node: java_new11628 Ref: doc-java_new11746 Node: javaMethod12376 Ref: doc-javaMethod12499 Node: java_invoke13225 Ref: doc-java_invoke13350 Node: java_get14123 Ref: doc-java_get14242 Node: java_set14859 Ref: doc-java_set14978 Node: javamethods15629 Ref: doc-javamethods15756 Node: javafields16975 Ref: doc-javafields17098 Node: msgbox18392 Ref: doc-msgbox18504 Node: errordlg19854 Ref: doc-errordlg19967 Node: helpdlg20771 Ref: doc-helpdlg20884 Node: inputdlg22115 Ref: doc-inputdlg22229 Node: listdlg24956 Ref: doc-listdlg25069 Node: questdlg27274 Ref: doc-questdlg27388 Node: warndlg28988 Ref: doc-warndlg29138 Node: How to distinguish between Octave and Matlab?30751 Ref: doc-FAQ31002 Node: How to make Java classes available?31650 Node: How to create an instance of a Java class?35404 Node: How can I handle memory limitations?36140 Node: How to compile the java package in Octave?39263 Node: Which TeX symbols are implemented in the dialog functions?44056  End Tag Table  Local Variables: coding: utf-8 End: