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59. 'break' jump statement






Jump statements transfer control to another part of your program. 'break' jump statement simply breaks the swith case/loops to comeout of the loop and continue with the program statements after the switch case/loop in which it was mentioned.

Program to demonstrate the usage of 'break' statement in 'switch' selection statements                                       

class SwitchBreak
{
   public static void main(String args[])
   {
      int a=1;
 
      switch(a)
      {
         case 0:
             System.out.println("Case 0");
             break;
         case 1:
             System.out.println("Case 1");
             break;
         default:
             System.out.println("Default Case");
       }
    }
 }

Output of this program:

Case 1

Observe that after printing the 'Case 1' text, the program tries to move to the next cases. But as we've mentioned break; statement, the switch case will be terminated and instead of going to the next case i.e. default

Using break statement to exit a 'for' loop

class ForBreak
{
   public static void main(String args[])
   {
      int a=3;

      for(int i=1;i<5;i++)
      {
   
          if(i==a)
          break;

       System.out.println("The value of i is "+i);
      }

   }
}

Output of this program:

The value of i is 1
The value of i is 2

i.e. when the value of i is equal to the value of a i.e. 3, the program will exit the 'for' loop because of the break statement written.

But we've to understand the break was not designed to provide a normal means by which a loop is terminated. Instead the break statement should be used to cancel a loop only when some sort of special situations occurs. If you go through this program, we have used break statement to exit the 'for' loop when the special situation if(i==a) is occurred. 

Using a break statement to exit a 'while' loop

class WhileLoopBreak
{
   public static void main(String args[])
   {
      int i=0;

      while(i<100)
      {
  if(i==10)
         break;

       System.out.print(i+" ");
       i++;
      }
    }
 }

Output of this program:

0 1 2 3 4 5 6  7 8 9 

Since the while loop got braked by the break; statement when the value of i reached 10, so the program printed values of i from 0 to 9 ,though it has the scope to print the values till 99. 

Using a break statement to exit a do-while loop

class DoWhileLoopBreak
{
   public static void main(String args[])
   {
      int i=0;

      do{
            if(i==10)
                break;

            System.out.print(i+" ");
             i++;

        }while(i<100);
    }
 }

Output of this program:

0 1 2 3 4 5 6  7 8 9 

Since the Do-while loop got braked by the break; statement when the value of i reached 10, so the program printed values of i from 0 to 9 ,though it has the scope to print the values till 99. 

Using break to exit the nested loops

class BreakNestedLoops
{
   public static void main(String args[])
   {

   first: for(int i=0;i<10;i++)        //Labelled this loop as 'first'
          {
   second: for(int j=0;j<10;j++)       //Labelled this loop as 'second'
           {
   Third: for(int k=0;k<10;k++)        //Labelled  this loop as 'third'
          {
             if((i+j+k)==1)
                break first;     //This will break the entire nested loop if the condition specified in the 'if' statement is met, since we've specified to break the loop labelled with 'first'

             System.out.println("The value of i+j+k is "+(i+j+k));
      }
    }
   }

   }
 }

Output of this program:

The value of i+j+k is 0

Break the inner loop 

class BreakInnerLoop
{
   public static void main(String args[])
   {

   first: for(int i=0;i<5;i++)        //Labelled this loop as 'first'
          {
   second: for(int j=0;j<5;j++)       //Labelled this loop as 'second'
           {

             if(j>3)
               break second;   //This will break the inner loop if the condition specified in the 'if' statement is met, since we've specified to break the loop labelled with 'second'

            System.out.print(j+" ");
   }

System.out.println();
 }

   }
 }

Output of this program:

0 1 2 3
0 1 2 3
0 1 2 3
0 1 2 3
0 1 2 3

If you observe clearly when the program execution enter the inner loop, it breaks when the value of j is 4, hence it wont print the value 4 in the output. Each time it the value of j becomes 4, the program execution breaks and the control goes to the outer loop labelled 'first' in this example and start its execution by incrementing the 'i' value

                                                                         



Please comment below to feedback or ask questions.

How to use the 'continue' jump statements will be explained in the next post.



2 comments:

Asha said...

Hi Arun,
I have doubt in below code:
first: for(int i=0;i<10;i++) //Labelled this loop as 'first'
{
second: for(int j=0;j<10;j++) //Labelled this loop as 'second'
{
Third: for(int k=0;k<10;k++) //Labelled this loop as 'third'
{
if((i+j+k)==1)
break first; //This will break the entire nested loop if the condition specified in the 'if' statement is met, since we've specified to break the loop labelled with 'first'

System.out.println("The value of i+j+k is "+(i+j+k));

firsttime it prints 0, I got this point.
For second iteration, i=1,j=1,k=1.. summation will be 3 which does not satisfy if((i+j+k)==1), then it has execute syso statement, correct?
so it has to print The value of i+j+k is 3.
I executed this locally and I got the output as you have mentioned.

KARTHICK-SUDARSHAN said...

For second iteration, i=1,j=0,k=0 and the ll satisfy if((i+j+k)==1 and therefore breaks.

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