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Java Reflection - Class.getDeclaredMethod() Examples

Java Reflection Java Java API 

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Class:

java.lang.Class

java.lang.Objectjava.lang.Objectjava.lang.Classjava.lang.Classjava.io.SerializableSerializablejava.lang.reflect.GenericDeclarationGenericDeclarationjava.lang.reflect.TypeTypejava.lang.reflect.AnnotatedElementAnnotatedElementLogicBig

Method:

public Method getDeclaredMethod(String name,
                                Class<?>... parameterTypes)
                         throws NoSuchMethodException,
                                SecurityException
Parameters:
name - the name of the method
parameterTypes - the parameter array
Returns:
the Method object for the method of this class matching the specified name and parameters

Examples


package com.logicbig.example.clazz;

import java.lang.reflect.Method;

public class GetDeclaredMethodExample {

    public static void main(String... args) throws NoSuchMethodException {
        Class<MyClass> c = MyClass.class;
        Method m = c.getDeclaredMethod("aMethod");
        System.out.println(m);

        m = c.getDeclaredMethod("anotherMethod", int.class);
        System.out.println(m);
    }

    private static class MyClass {
        private void aMethod() { }

        public void anotherMethod(int i) { }
    }
}

Output

private void com.logicbig.example.clazz.GetDeclaredMethodExample$MyClass.aMethod()
public void com.logicbig.example.clazz.GetDeclaredMethodExample$MyClass.anotherMethod(int)




Attempting to access super class method:

package com.logicbig.example.clazz;

import java.lang.reflect.Method;

public class GetDeclaredMethodExample2 {
    public static void main(String... args) throws NoSuchMethodException {
        Class<MyClass> c = MyClass.class;
        Method m = c.getDeclaredMethod("aSuperClassMethod");
        System.out.println(m);
    }

    private static class MyClass extends TheSuperClass {}

    private static class TheSuperClass {
        public void aSuperClassMethod() {
        }
    }
}

Output

Caused by: java.lang.NoSuchMethodException: com.logicbig.example.clazz.GetDeclaredMethodExample2$MyClass.aSuperClassMethod()
	at java.base/java.lang.Class.getDeclaredMethod(Class.java:2432)
	at com.logicbig.example.clazz.GetDeclaredMethodExample2.main(GetDeclaredMethodExample2.java:14)
	... 6 more




Method of an anonymous class:

package com.logicbig.example.clazz;

import java.lang.reflect.Method;

public class GetDeclaredMethodExample3 {

    public static void main(String... args) throws NoSuchMethodException {
        Runnable r = new Runnable() {
            @Override
            public void run() {
            }

            public void anotherMethod() {}
        };

        Method m = r.getClass().getDeclaredMethod("anotherMethod");
        System.out.println(m);
    }
}

Output

public void com.logicbig.example.clazz.GetDeclaredMethodExample3$1.anotherMethod()

See Also