iSeries fix for No such Method found error when calling Java program from RPGLE
When calling a Java program from RPGLE you must define prototype for each Method that you want to call from your RPGLE program. The Java program may have lot of methods defined but you don't have to prototype all of them, only the ones that you want to call from your RPGLE program. Let take a sample Java program and see how we can define prototypes for the methods in it.Sample Java Program
package com.as400samplecode; public class CallThis { public static void main(String[] args) { String result = myproc("as400samplecode"); System.out.println(result); } public static String myproc(String abc) { String xyz = abc; return xyz; } public static void myvoid(String abc) { String xyz = abc; System.out.println(xyz); } }
RPGLE prototype definitions for the CallThis Java Program
* Prototype for CallThis's myproc Method d myproc PR o EXTPROC(*JAVA: d 'com.as400samplecode.CallThis': d 'myproc') d Class (*JAVA:'java.lang.String') d STATIC d String o Class (*JAVA:'java.lang.String') d Const * Prototype for CallThis's myproc Method d myvoid PR EXTPROC(*JAVA: d 'com.as400samplecode.CallThis': d 'myvoid') d STATIC d String o Class (*JAVA:'java.lang.String') d Const
How to check Methods defined in Java Class to match signature
Go to into Qshell using command QSH and press ENTERChange directory to the class object using cd /directory1/directory2/..
Use command javap -s com.as400samplecode.callThis
Output when you run the above command
Compiled from "CallThis.java"
public class com.as400samplecode.CallThis extends java.lang.Object{
public com.as400samplecode.CallThis();
Signature: ()V
public static void main(java.lang.String[]);
Signature: ([Ljava/lang/String;)V
public static java.lang.String myproc(java.lang.String);
Signature: (Ljava/lang/String;)Ljava/lang/String;
public static void myvoid(java.lang.String);
Signature: (Ljava/lang/String;)V
}
javap command options include
-b Backward compatibility with javap in JDK 1.1 -c Disassemble the code -classpath <pathlist> Specify where to find user class files -extdirs <dirs> Override location of installed extensions -help Print this usage message -J<flag> Pass <flag> directly to the runtime system -l Print line number and local variable tables -public Show only public classes and members -protected Show protected/public classes and members -package Show package/protected/public classes and members (default) -private Show all classes and members -s Print internal type signatures -bootclasspath <pathlist> Override location of class files loaded by the bootstrap class loader -verbose Print stack size, number of locals and args for methods If verifying, print reasons for failure
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