Selection statements

The selection statements have four variations:

• if statement
• if...else statement
• if...else if-...-else statement
• switch...case statement

if 

The simple if statement allows executing a certain statement or block conditionally, only when the result of the expression evaluation is true:

if(booelan expression){
  //do something
} 

Here are a few examples:

if(true) System.out.println("true");    //1: true
if(false) System.out.println("false");  //2:

int x = 1, y = 5;
if(x > y) System.out.println("x > y");  //3:
if(x < y) System.out.println("x < y");  //4: x < y

if((x + 5) > y) {                       //5: x + 5 > y
  System.out.println("x + 5 > y");    
x = y;
}

if(x == y){                             //6: x == y
  System.out.println("x == y");       
}

Statement 1 prints true. Statements 2 and 3 print nothing. Statement 4 prints x < y. Statement 5 prints x + 5 > y. We used braces to create a block because we wanted the x = y statement to be executed...