Get Methods using Reflection

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Get Methods using Reflection

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In this example we shall explain with a simple example to get the methods of a class using the reflection. You can list the public and private methods of an object using the following steps:

  • Get the Class instance of the class which you want to list the methods. In this example get the Class instance of Math class.
  • Call getMethods() method from the Class instance which returns the Method[] array which contains the public fields.
  • Call getDeclaredMethods() method from the Class instance which returns the Method[] array which contains all the methods whether it is private, public or default.

Lets look at this example to list of methods of java.lang.Math class:

package javabeat.net.reflection;

import java.lang.reflect.Method;
/**
 * List Methods in a Class using Reflection API
 * @author krishna
 *
 */
public class JavaBeatReflectionExample {

	public static void main(String[] args) throws Exception {

		// Get the Class instance for Math
		Class<?> mathClass = java.lang.Math.class;

		//Declare Fields class
		Method[] refMethods;

		// List all the public fields in the Math class
		refMethods = mathClass.getMethods();
		for (int i = 0; i < refMethods.length; i++) {
			System.out.println("Public Field: " + refMethods[i]);
		}

		System.out.println();

		// List all the fields in the Math class
		refMethods = mathClass.getDeclaredMethods();
		for (int i = 0; i < refMethods.length; i++) {
			System.out.println("Field: " + refMethods[i]);
		}

	}
}

Output

Public Field: public static int java.lang.Math.abs(int)
Public Field: public static long java.lang.Math.abs(long)
Public Field: public static float java.lang.Math.abs(float)
Public Field: public static double java.lang.Math.abs(double)
Public Field: public static double java.lang.Math.sin(double)
Public Field: public static double java.lang.Math.cos(double)
Public Field: public static double java.lang.Math.tan(double)
Public Field: public static double java.lang.Math.atan2(double,double)
Public Field: public static double java.lang.Math.sqrt(double)
Public Field: public static double java.lang.Math.log(double)
Public Field: public static double java.lang.Math.log10(double)
Public Field: public static double java.lang.Math.pow(double,double)
Public Field: public static double java.lang.Math.exp(double)
Public Field: public static int java.lang.Math.min(int,int)
Public Field: public static long java.lang.Math.min(long,long)
Public Field: public static float java.lang.Math.min(float,float)
Public Field: public static double java.lang.Math.min(double,double)
Public Field: public static int java.lang.Math.max(int,int)
Public Field: public static long java.lang.Math.max(long,long)
Public Field: public static float java.lang.Math.max(float,float)
Public Field: public static double java.lang.Math.max(double,double)
Public Field: public static double java.lang.Math.scalb(double,int)
Public Field: public static float java.lang.Math.scalb(float,int)
Public Field: public static int java.lang.Math.getExponent(float)
Public Field: public static int java.lang.Math.getExponent(double)
Public Field: public static double java.lang.Math.signum(double)
Public Field: public static float java.lang.Math.signum(float)
Public Field: public static double java.lang.Math.asin(double)
Public Field: public static double java.lang.Math.acos(double)
Public Field: public static double java.lang.Math.atan(double)
Public Field: public static double java.lang.Math.toRadians(double)
Public Field: public static double java.lang.Math.toDegrees(double)
Public Field: public static double java.lang.Math.cbrt(double)
Public Field: public static double java.lang.Math.IEEEremainder(double,double)
Public Field: public static double java.lang.Math.ceil(double)
Public Field: public static double java.lang.Math.floor(double)
Public Field: public static double java.lang.Math.rint(double)
Public Field: public static int java.lang.Math.round(float)
Public Field: public static long java.lang.Math.round(double)
Public Field: public static double java.lang.Math.random()
Public Field: public static double java.lang.Math.ulp(double)
Public Field: public static float java.lang.Math.ulp(float)
Public Field: public static double java.lang.Math.sinh(double)
Public Field: public static double java.lang.Math.cosh(double)
Public Field: public static double java.lang.Math.tanh(double)
Public Field: public static double java.lang.Math.hypot(double,double)
Public Field: public static double java.lang.Math.expm1(double)
Public Field: public static double java.lang.Math.log1p(double)
Public Field: public static double java.lang.Math.copySign(double,double)
Public Field: public static float java.lang.Math.copySign(float,float)
Public Field: public static double java.lang.Math.nextAfter(double,double)
Public Field: public static float java.lang.Math.nextAfter(float,double)
Public Field: public static double java.lang.Math.nextUp(double)
Public Field: public static float java.lang.Math.nextUp(float)
Public Field: public final native void java.lang.Object.wait(long) throws java.lang.InterruptedException
Public Field: public final void java.lang.Object.wait(long,int) throws java.lang.InterruptedException
Public Field: public final void java.lang.Object.wait() throws java.lang.InterruptedException
Public Field: public boolean java.lang.Object.equals(java.lang.Object)
Public Field: public java.lang.String java.lang.Object.toString()
Public Field: public native int java.lang.Object.hashCode()
Public Field: public final native java.lang.Class java.lang.Object.getClass()
Public Field: public final native void java.lang.Object.notify()
Public Field: public final native void java.lang.Object.notifyAll()

Field: public static int java.lang.Math.abs(int)
Field: public static long java.lang.Math.abs(long)
Field: public static float java.lang.Math.abs(float)
Field: public static double java.lang.Math.abs(double)
Field: public static double java.lang.Math.sin(double)
Field: public static double java.lang.Math.cos(double)
Field: public static double java.lang.Math.tan(double)
Field: public static double java.lang.Math.atan2(double,double)
Field: public static double java.lang.Math.sqrt(double)
Field: public static double java.lang.Math.log(double)
Field: public static double java.lang.Math.log10(double)
Field: public static double java.lang.Math.pow(double,double)
Field: public static double java.lang.Math.exp(double)
Field: public static int java.lang.Math.min(int,int)
Field: public static long java.lang.Math.min(long,long)
Field: public static float java.lang.Math.min(float,float)
Field: public static double java.lang.Math.min(double,double)
Field: public static int java.lang.Math.max(int,int)
Field: public static long java.lang.Math.max(long,long)
Field: public static float java.lang.Math.max(float,float)
Field: public static double java.lang.Math.max(double,double)
Field: public static double java.lang.Math.scalb(double,int)
Field: public static float java.lang.Math.scalb(float,int)
Field: public static int java.lang.Math.getExponent(float)
Field: public static int java.lang.Math.getExponent(double)
Field: public static double java.lang.Math.signum(double)
Field: public static float java.lang.Math.signum(float)
Field: public static double java.lang.Math.asin(double)
Field: public static double java.lang.Math.acos(double)
Field: public static double java.lang.Math.atan(double)
Field: public static double java.lang.Math.toRadians(double)
Field: public static double java.lang.Math.toDegrees(double)
Field: public static double java.lang.Math.cbrt(double)
Field: public static double java.lang.Math.IEEEremainder(double,double)
Field: public static double java.lang.Math.ceil(double)
Field: public static double java.lang.Math.floor(double)
Field: public static double java.lang.Math.rint(double)
Field: public static int java.lang.Math.round(float)
Field: public static long java.lang.Math.round(double)
Field: private static synchronized void java.lang.Math.initRNG()
Field: public static double java.lang.Math.random()
Field: public static double java.lang.Math.ulp(double)
Field: public static float java.lang.Math.ulp(float)
Field: public static double java.lang.Math.sinh(double)
Field: public static double java.lang.Math.cosh(double)
Field: public static double java.lang.Math.tanh(double)
Field: public static double java.lang.Math.hypot(double,double)
Field: public static double java.lang.Math.expm1(double)
Field: public static double java.lang.Math.log1p(double)
Field: public static double java.lang.Math.copySign(double,double)
Field: public static float java.lang.Math.copySign(float,float)
Field: public static double java.lang.Math.nextAfter(double,double)
Field: public static float java.lang.Math.nextAfter(float,double)
Field: public static double java.lang.Math.nextUp(double)
Field: public static float java.lang.Math.nextUp(float)

Related posts:

  1. Get Fields using Reflection
  2. Hiding and Overriding Methods In Java
  3. Invoke Method using Reflection API
  4. Querying Class Information at Runtime using Java Reflection API
  5. Generic Methods in Java 5.0

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