Chapter 1. Language Enhancements

Chapter 1. Language Enhancements
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1.1. Use String in the switch statement


	[JAVA_TUTORIAL_SWITCH] The switch Statement

In Java SE 7 and later, you can use a String object in the switch statement's expression. The following code example, StringSwitch, displays the color RGB based on the value of the String named color:

public class StringSwitch {
    public static void main(String[] args) {
        String color = "black";
        switch (color) {
            case "white":
                System.out.print(color + " RGB: ffffff");
                break;
            case "black":
                System.out.print(color + " RGB: 000000");
                break;
            default:
                System.out.print(color + " RGB: UNKNOWN");
                break;
        }
    }
}

The output from this code is:

black RGB: 000000

The String in the switch expression is compared with the expressions associated with each case label as if the String.equals(...) method were being used. Two things to keep in mind:

Check for null before the switch:

public class StringSwitchNull {
    public static void main(String[] args) {
        String color = null;
        switch (color) {
            case "white":
                System.out.print(color + " RGB: ffffff");
                break;
            case "black":
                System.out.print(color + " RGB: 000000");
                break;
            default:
                System.out.print(color + " RGB: UNKNOWN");
                break;
        }
    }
}

result:

Exception in thread "main" java.lang.NullPointerException
	at c1.s1.StringSwitchNull.main(StringSwitchNull.java:9)
Java Result: 1

Check for different case letters before the switch:

public class StringSwitchCase {
    public static void main(String[] args) {
        String color = "BlAcK";
        switch (color) {
            case "white":
                System.out.print(color + " RGB: ffffff");
                break;
            case "black":
                System.out.print(color + " RGB: 000000");
                break;
            default:
                System.out.print(color + " RGB: UNKNOWN");
                break;
        }
    }
}

result:

BlAcK RGB: UNKNOWN

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Part I. Exam Objectives	Home	1.2. Use binary literals, numeric literals with underscores