| 1 | <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> |
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| 2 | <html> |
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| 3 | <head> |
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| 4 | <title>J User's Guide - Calling Java From Lisp</title> |
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| 5 | <LINK REL="stylesheet" HREF="j.css" TYPE="text/css"> |
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| 6 | </head> |
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| 7 | <body> |
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| 8 | <a href="contents.html">Top</a> |
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| 9 | <hr> |
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| 10 | <h1>Calling Java From Lisp</h1> |
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| 11 | <hr> |
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| 12 | <p> |
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| 13 | Programs in j's built-in Lisp can use the following functions to instantiate |
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| 14 | Java classes and call Java methods: |
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| 15 | <p> |
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| 16 | <a name="jclass">• jclass</a><dl><dd> |
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| 17 | <p> |
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| 18 | jclass <i>class-name</i> => <i>class-ref</i> |
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| 19 | <p> |
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| 20 | Returns a reference to the specified Java class. |
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| 21 | <pre> |
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| 22 | (jclass "java.lang.String") => |
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| 23 | #<JAVAOBJECT ... class java.lang.String></pre> |
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| 24 | </dl> |
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| 25 | <a name="jconstructor">• jconstructor</a><dl><dd> |
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| 26 | <p> |
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| 27 | jconstructor <i>class-name &rest parameter-class-names</i> => <i>constructor-ref</i> |
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| 28 | <p> |
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| 29 | Returns a reference to the specified constructor. |
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| 30 | <pre> |
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| 31 | (jconstructor "java.lang.StringBuffer") => |
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| 32 | #<JAVAOBJECT ... public java.lang.StringBuffer()> |
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| 33 | |
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| 34 | (jconstructor "java.lang.StringBuffer" "java.lang.String") => |
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| 35 | #<JAVAOBJECT ... public java.lang.StringBuffer(java.lang.String)></pre> |
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| 36 | Java primitive types may be used as parameter class names: |
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| 37 | <pre> |
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| 38 | (jconstructor "java.lang.StringBuffer" "int") => |
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| 39 | #<JAVAOBJECT ... public java.lang.StringBuffer(int)></pre> |
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| 40 | </dl> |
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| 41 | <a name="jmethod">• jmethod</a><dl><dd> |
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| 42 | <p> |
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| 43 | jmethod <i>class-name method-name &rest parameter-class-names</i> => <i>method-ref</i> |
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| 44 | <p> |
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| 45 | Returns a reference to the specified method. |
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| 46 | <pre> |
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| 47 | (jmethod "java.lang.String" "length") => |
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| 48 | #<JAVAOBJECT ... java.lang.String.length()> |
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| 49 | |
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| 50 | (jmethod "java.lang.StringBuffer" "append" "java.lang.String") => |
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| 51 | #<JAVAOBJECT ... java.lang.StringBuffer.append(java.lang.String)></pre> |
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| 52 | The parameter class names may be omitted if there is no ambiguity: |
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| 53 | <pre> |
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| 54 | (jmethod "java.lang.StringBuffer" "setLength") => |
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| 55 | #<JAVAOBJECT ... public synchronized void java.lang.StringBuffer.setLength(int)></pre> |
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| 56 | </dl> |
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| 57 | <a name="jstatic">• jstatic</a><dl><dd> |
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| 58 | <p> |
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| 59 | jstatic <i>method-ref class-ref &rest args</i> => <i>result</i> |
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| 60 | <p> |
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| 61 | Invokes a static method. |
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| 62 | <p> |
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| 63 | If <i>method-ref</i> is a string, it is assumed to name a method. <i>class-ref</i> |
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| 64 | must be a class name or a class reference returned by <a href="#jclass">jclass</a>. |
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| 65 | <pre> |
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| 66 | (jstatic "currentTimeMillis" "java.lang.System") => |
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| 67 | 1043330903587</pre> |
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| 68 | <p> |
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| 69 | If <i>method-ref</i> is a method reference returned by <a href="#jmethod">jmethod</a>, |
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| 70 | the <i>class-ref</i> argument is ignored. |
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| 71 | <pre> |
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| 72 | (jstatic (jmethod "java.lang.System" "currentTimeMillis") nil) => |
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| 73 | 1043330944932</pre> |
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| 74 | </dl> |
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| 75 | <a name="jnew">• jnew</a><dl><dd> |
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| 76 | <p> |
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| 77 | jnew <i>constructor &rest args</i> => <i>object-ref</i> |
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| 78 | <p> |
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| 79 | Invokes a constructor. |
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| 80 | <pre> |
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| 81 | (jnew (jconstructor "java.lang.String" "java.lang.String") "this is a test") => |
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| 82 | #<JAVAOBJECT [java.lang.String] this is a test></pre> |
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| 83 | </dl> |
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| 84 | <a name="jcall">• jcall</a><dl><dd> |
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| 85 | <p> |
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| 86 | jcall <i>method-ref instance-ref &rest args</i> => <i>result</i> |
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| 87 | <p> |
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| 88 | Invokes a method on a Java object. |
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| 89 | <pre> |
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| 90 | (setq x (jnew (jconstructor "java.lang.String" "java.lang.String") "this is a test")) => |
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| 91 | #<JAVAOBJECT [java.lang.String] this is a test> |
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| 92 | |
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| 93 | (defconstant length-method (jmethod "java.lang.String" "length")) => |
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| 94 | LENGTH-METHOD |
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| 95 | |
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| 96 | (jcall length-method x) => |
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| 97 | 14</pre> |
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| 98 | </dl> |
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| 99 | </body> |
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| 100 | </html> |
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