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)
Get Fields using Reflection