In Java, the if-else construct is used to check if a condition is met then do something, otherwise do something else. The structure looks like follows:
if (condition) { // do something if condition is met } else { // do something else if condition is not met }
where condition can be a variable, a method call or an expression that must be evaluated to true. The code inside if block can be any Java statements. For example:
boolean passed = false; // try something... if (passed) { System.out.println("Congratulations!"); } else { System.out.println("Try again next time!"); }
The construct can be extended for multiple if-else pairs:
if (condition1) { // do something if condition1 is met } else if (condition2) { // do something if condition2 is met } else if (condition3) { // do something if condition3 is met } else { // do something else if none condition is met }
For example:
int score = calculateScore(); if (score > 90) { System.out.println("Excellent"); } else if (score > 70) { System.out.println("Very good"); } else if (score > 50) { System.out.println("Above average"); } else { System.out.println("Very bad"); }
If there is only one statement after the if or else, the opening and closing curly braces can be removed. For example:
if (score < 10) score = score + 10; else score = score - 10;
See all keywords in Java.