Java: Generate Annotation with default value using Codemodel

Question

I use the Sun CodeModel code generator for my project. During this I came to the point to generate an annotation class. This class would have an array member which takes an empty array as default values. See the following example:

public class Container {
    public @interface MyAnnotation {
        MyValue[] myValues() default {};
    }
}

I used this code to generate the Annotation

JCodeModel codeModel = new JCodeModel();
JDefinedClass myValueClass = codeModel._class(JMod.PUBLIC, "MyValue", ClassType.CLASS);
JDefinedClass containerClass = codeModel._class(JMod.PUBLIC, "Container", ClassType.CLASS);
JDefinedClass annotationClass = containerClass._annotationTypeDeclaration("MyAnnotation");
annotationClass.method(JMod.NONE, myValueClass.array(), "myValues");

but I have no idea how to generate the default declaration. It only generates the following:

public class Container {
    public @interface MyAnnotation {
        MyValue[] myValues();
    }
}

score 2 · Accepted Answer · answered May 08 '15 at 04:11

JMethod has a method declareDefaultValue that allows you to define a default value for an annotation method. The trick after that is to generate the empty array {}. I wasn't able to figure out how to do this using the existing classes, but you can easily define this using a JExpressionImpl:

JCodeModel codeModel = new JCodeModel();
JDefinedClass myValueClass = codeModel._class(JMod.PUBLIC, "MyValue", ClassType.CLASS);
JDefinedClass containerClass = codeModel._class(JMod.PUBLIC, "Container", ClassType.CLASS);
JDefinedClass annotationClass = containerClass._annotationTypeDeclaration("MyAnnotation");
JMethod method = annotationClass.method(JMod.NONE, myValueClass.array(), "myValues");
method.declareDefaultValue(new JExpressionImpl(){
    @Override
    public void generate(JFormatter f) {
        f.p("{}");
    }
});

This generates the following:

public @interface MyAnnotation {
    MyValue[] myValues() default {};
}

Java: Generate Annotation with default value using Codemodel

1 Answers1