The Difference Between Method Overloading and Method Overriding

When taking the Oracle Certified Professional, Java SE 6 Programmer exam, one of the tricks used to try to catch you out is to try to confuse you over the meanings of overriding and overloading methods and I guess that this is because they have similar sounding names. This blog clarifies all that - take a look at the code...

/**
 * Class that demonstrates Overloading of methods. myMethod() has been overloaded three
 * times...
 */
public class OverloadExample {

  public void myMethod() {
    System.out.println("Blank");
  }

  public void myMethod(String str) {
    System.out.println("Input is: " + str);
  }

  public void myMethod(int arg) {
    System.out.println("Value is: " + arg);
  }

  public void myMethod(double arg) {
    System.out.println("Value is: " + arg);
  }

  public static void main(String[] args) {

    OverloadExample example = new OverloadExample();
    example.myMethod();
    example.myMethod("Hello");
    example.myMethod(42);
    example.myMethod(23.3);
  }
}

The code above demonstrates overloading, whilst the code below demonstrates overriding:

/**
 * Class that demonstrates Overriding of methods. myMethod() has been overridden twice...
 */
public class OverrideExample extends OverloadExample {

  @Override
  public void myMethod(String str) {
    System.out.println("New input is: " + str);
  }

  @Override
  public void myMethod(int arg) {
    System.out.println("New value is: " + arg);
  }

  public static void main(String[] args) {
    OverrideExample example = new OverrideExample();
    example.myMethod();
    example.myMethod("Hello");
    example.myMethod(42);
    example.myMethod(23.3);
  }
}

The only tip here is to read the question carefully: overloading is not overriding they just sound similar.