Methods in Java

Methods

  • A method is the block of code that can be called anywhere in a program. It contains a group of statements to perform an operation.
  • Combination of method name and parameter is known as method signature.
  • Required elements of method declaration are the method name, return type, a pair of parenthesis and body between braces {}.
Syntax:

modifier returntype methodName (parameter)
{
     // body
}


Example:

public static int display (int a, String b)
{
     //method body
}


where,
public static: modifiers
int: return type
display: method name
int a, String b: parameters
display (int a, String b): method signature

Example: Program for method

Program for swapping two numbers without using third variable.

class SwapNumber
{
     public static void main(String[] args)
     {
          int n1 = 30;
          int n2 = 45;
          int temp;
          System.out.println("Before swapping, n1 = " + n1 + " and n2 = " + n2);
          swapMethod(n1, n2);
     }
     public static void swapMethod(int n1, int n2)
    {
          n1 = n1 + n2;
          n2 = n1 - n2;
          n1 = n1 - n2;
          System.out.println("After swapping, n1 = " + n1 + "  and n2 = " + n2);
     }
}


Output:
Before swapping, n1 = 30 and n2 = 45
After swapping, n1 = 45  and n2 =30

Static Method

  • When a method is declared with static keyword, it is known as a static method.
  • A static method can be invoked without creating an object of the class.
  • Static method belongs to class level.

Static Block

  • Static block is also called as an initialization block.
  • It is executed only once before main method at the time of class loading.
  • A class can have any number of a static block.
Syntax:

class classname
{
     Static
     {
          //code          
     }
}


Example: Sample program for static method

public class StaticMethod
{
     static
     {
          System.out.println("First static block");      //static block
     }
     static void m1 ()
     {
          System.out.println("Static method");
     }
     void m2()
     {
          System.out.println("Non-static method");
     }
     Static
     {
          System.out.println("Second static block");          //static block
     }
     public static void main(String args[])
     {
          m1();     //invoked static method
          StaticMethod sm = new StaticMethod();
          sm.m2();     // invoked non static method
     }
}


Output:
First static block
Second static block
Static method
Non-static method

The “finalize ()” method

  • Java runtime calls finalize () method when an object is about to get garbage collector.
  • It is called explicitly to identify the task to be performed.
  • The finalize() method is always declared as protected because it prevents access to the outside class.
Syntax:

protected void finalize ()
{
     // finalize code
}

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