Control Statements in java|| Selection Statements || Iteration Statements || Jump statements ||

 Control Statements:

Selection Statements:

There are two selection statements in Java: if and switch:

a. if

Syntax : if (condition) statementsIfTrue

e.g. if (weight == 0) Sytem.out.println(“Error: Weight can’t be zero”);

if_else

Syntax: if (condition) statementsIfTrue; else statementsIfFalse;

e.g. if (password == mjs)

{ System.out.println(“Welcome”);

Login(); }

else { System.out.println(“Password not correct”); exitSystem(); }

if_else_if

Syntax: if (condition1) statement1 else if(condition2) statement2 else statement3

e.g. if (gender == female)

if (age > 25)

Sytem.out.println(“Woman”);

else

System.out.println(“Girl”);

else if (gender == male)

System.out.println(“Man”);

else

System.out.println(“Boy”);

b. switch

The expression must be of type byte, short, int, or char; each of the values specified in the case statements must be of a type compatible with the expression. Each case value must be a unique literal (that is, it must be a constant, not a variable). Duplicate case values are not allowed.

Syntax:

switch(expression)

 {

case value1: statements; break;

case value2: statements; break;

case valuen: statements; break;

default:

default statements; }

Example:

switch(choice) {

case 'o': open(); break;

case 'c': close(); break;

case 'e': exit(); break;

default:

system.out.println(“not valid choice”);

}

Switch Example:

switch(intM)

{

case 1: //If M is 1

case 2: //If M is 2

case 3:

case 4:

System.out.println(“M is less than 5”);

break;

case 5:

System.out.println(“M is 5”);

}

Iteration Statements:

Jump Statements:

Java supports three jump statements:

1. break; break statements has three basic uses:

a. In switch statement to terminate case.

b. Used to exit from loops

e.g. for(int m=1; m<=10; m++) {

if(m == 5) break; /*break loop when m is 5*/ System.out.println(m); }

c. Used as civilized form of goto.

By using this form of break, you can break out of one or more blocks of code. These blocks need not be part of a loop or a switch. They can be any block. You can use a labeled break statement to exit from a set of nested locks. But you cannot use break to transfer control to a block of code that does not enclose the break statement.

Syntax : break label;

e.g. // Using break as a civilized form of goto.

class Break {

public static void main(String args[])

{

boolean t = true;

first: {

second: {

third: {

System.out.println("Before the break.");

if(t) break second; // break out of second block

System.out.println("This won't execute");

}

System.out.println("This won't execute");

}

System.out.println("This is after second block.");

}

}

}

2. continue; continue statement has two uses:

a. In loops: In while and do-while loops, a continue statement causes control to be transferred directly to the conditional expression that controls the loop. In a for loop, control goes first to the iteration portion of the for statement and then to the conditional expression. For all three loops, any intermediate code is bypassed.

e.g. for(int m = 1; m<=5; m++)

{ if(m==3) continue; /*Skip printing of 3*/ System.out.println(m); }

b. As wment,ith the break state continue may specify a label to describe which enclosing loop to continue. Syntax: continue label;

3. Return

The return statement is used to explicitly return from a method. And also used to return any value or result to caller.