一个类如何访问自己的类名？

Question

I use an java application which generates a class dynamically. Via an ant script the source code will be produced for a give classname and a class template.

In the template for the class I need to know the name of even this class, to call a static method of the class.

Example. The class will be named "VersionInfo". Then in static main() of it I want to call the static method: VersionInfo.getId(). But I don't know the class-name.

Is there an equivalent to "this" for static contexts or some Utility-Class for such a purpose?

Answer 1

如果您是通过Ant创建类，那么为什么不生成一个返回类名的静态方法getClassName？

Answer 2

如果你的main方法驻留在同一个类中，你可以在main方法中调用getId() 。

Answer 3

So you're saying that it should generate this?

public class VersionInfo{ // VersionInfo class name changes, per problem description
    public static void main(){
        System.out.println(getId()); 
// but in the main within the class,we don't need the classname to call a static method
    }
    public static string getId(){
       return "what's the problem?";
    }
}

Is there something missing from the description, that you're calling some OTHER class' static method by an unknown-to-the-template name?

Answer 4

There's a nasty workaround:

public static final Class THIS_CLASS = new Object() {
  public Class getParentClass() {
    return getClass().getEnclosingClass();
  }
}.getParentClass();

Answer 5

I'm not sure I understand. If you generate the class VersionInfo yourself, why can't you get the class name from the code that generates the class?

Answer 6

Try this:

package uk.co.farwell.stack_overflow;

public class Test_847708 {
    private final static String getId() {
        return "string";
    }

    public static void main(String args[]) {
        System.out.println("getId=" + getId());
    }

}

Answer 7

You cannot use the key "this" in a static context.

Instead, if you want to call dynamically a static function, you can use java reflection .

I cannot help you further for java reflection because I never use it, but I already use it in .Net and it's a powerful tools.

Answer 8

The cleanest answer to the question might be to make a third class with a static, known, name that is generated by the ANT script which references the dynamic class name, and then have your main method reference that known class.

If for some reason that isn't enough, then combine Joachim Sauer and Melursus answer, and get the class name, and then get the method via reflection:

Method m = THIS_CLASS.getDeclaredMethod("getId", null);
Object result = m.invoke(null, null);