I have to edit Labels that are being defined inside the constructor of a class. I decided to redefine them at the end of the constructor.

public class StaticPraxMMod {

    private static final String PRAXFRAME = "com.praxemu.client.graphics.widgets.PraxFrame";

    public static void main(String[] args) throws Exception {    
        ClassPool classPool = ClassPool.getDefault();
        addEVLink(classPool);

    }

    private static void addEVLink(ClassPool classPool) throws NotFoundException, CannotCompileException, IOException {
        CtClass praxFrameClass = classPool.get(PRAXFRAME);
        CtConstructor praxFrameConstructor = praxFrameClass.getConstructors()[0]/*(new CtClass[] {})*/;
        //praxFrameClass.addConstructor(praxFrameConstructor);

        praxFrameConstructor.insertAfter("localLabel25 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.Ô00000)).append(\"\").toString() + \"peanuts\");\n" 
                "localLabel26 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.class)).append(\"\").toString() + \"peanuts\");\n" +
                "localLabel27 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.õ00000)).append(\"\").toString() + \"peanuts\");\n" +
                "localLabel28 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.ÓO0000)).append(\"\").toString() + \"peanuts\");\n" +
                "localLabel29 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.interface)).append(\"\").toString() + \"peanuts\");\n" +
                "localLabel25.setTheme(\"label-value\");\n" +
                "localLabel26.setTheme(\"label-value\");\n" +
                "localLabel27.setTheme(\"label-value\");\n" +
                "localLabel28.setTheme(\"label-value\");\n" +
                "localLabel29.setTheme(\"label-value\");");
        //praxFrameClass.toBytecode();
        praxFrameClass.writeFile(".");

    }
}

When running it, I get this :

Exception in thread "main" javassist.CannotCompileException: [source error] no such field: localLabel25
    at javassist.CtBehavior.insertAfter(CtBehavior.java:873)
    at javassist.CtBehavior.insertAfter(CtBehavior.java:788)
    at StaticPraxMMod.addEVLink(StaticPraxMMod.java:27)
    at StaticPraxMMod.main(StaticPraxMMod.java:18)
Caused by: compile error: no such field: localLabel25
    at javassist.compiler.TypeChecker.fieldAccess(TypeChecker.java:819)
    at javassist.compiler.TypeChecker.atFieldAssign(TypeChecker.java:271)
    at javassist.compiler.JvstTypeChecker.atFieldAssign(JvstTypeChecker.java:84)
    at javassist.compiler.TypeChecker.atAssignExpr(TypeChecker.java:230)
    at javassist.compiler.ast.AssignExpr.accept(AssignExpr.java:39)
    at javassist.compiler.CodeGen.doTypeCheck(CodeGen.java:242)
    at javassist.compiler.CodeGen.atStmnt(CodeGen.java:330)
    at javassist.compiler.ast.Stmnt.accept(Stmnt.java:50)
    at javassist.compiler.Javac.compileStmnt(Javac.java:569)
    at javassist.CtBehavior.insertAfterAdvice(CtBehavior.java:888)
    at javassist.CtBehavior.insertAfter(CtBehavior.java:847)

I tried adding the full package path to labels but it doesn't change a thing.

I also tried this :

praxFrameConstructor.insertAfter("de.matthiasmann.twl.Label localLabel25 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.Ô00000)).append(\"\").toString() + \"peanuts\");\n");
praxFrameConstructor.insertAfter("de.matthiasmann.twl.Label localLabel26 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.class)).append(\"\").toString() + \"peanuts\");");
praxFrameConstructor.insertAfter("de.matthiasmann.twl.Label localLabel27 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.õ00000)).append(\"\").toString() + \"peanuts\");");
praxFrameConstructor.insertAfter("de.matthiasmann.twl.Label localLabel28 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.ÓO0000)).append(\"\").toString() + \"peanuts\");");
praxFrameConstructor.insertAfter("de.matthiasmann.twl.Label localLabel29 = new de.matthiasmann.twl.Label(new StringBuilder().append(paramsuper.õo0000().o00000(null.interface)).append(\"\").toString() + \"peanuts\");");
praxFrameConstructor.insertAfter("localLabel25.setTheme(\"label-value\");");
praxFrameConstructor.insertAfter("localLabel26.setTheme(\"label-value\");");
praxFrameConstructor.insertAfter("localLabel27.setTheme(\"label-value\");");
praxFrameConstructor.insertAfter("localLabel28.setTheme(\"label-value\");");
praxFrameConstructor.insertAfter("localLabel29.setTheme(\"label-value\");");

Which yields a "no such class: de.matthiasmann.twl.Label" error.

Basically, I barely have an idea how I should achieve this.

Thanks for your help.