Java Switch statement (detailed usage explanation)

Switch statement is used to make decisions in Java. Unlike if-then and if-then-else statements, a switch statement can have many possible execution paths.

Grammar

The general form of the switch statement is:

switch (expression) {
    case value1:
         break;
    case value2:
         break;
    ... case valueN:
         break;
    default:

}

The type of expression must be byte, short, int, or char; each value specified in the case statement must be of a type compatible with the expression.

Note: Starting from Java 7, String is also supported in expressions.

Flowchart

Example:

class Switch {
    public static void main(String args[]) {
        int month = 4;
        String season;
        switch (month) {
            case 12:
            case 1:
            case 2:
                season = "冬天";
                break;
            case 3:
            case 4:
            case 5:
                season = "春天";
                break;
            case 6:
            case 7:
            case 8:
                season = "夏天";
                break;
            case 9:
            case 10:
            case 11:
                season = "秋天";
                break;
            default:
                season = "Bogus Month";
        }
        System.out.println("四月是 " + season + ".");
    }
}

Output:

四月是春天.

Here, switch The expression month in the statement matches the value 4 in case, so the season is assigned the value spring.

There are three important features of the switch statement that need to be noted:

1. The difference between switch and if is that the switch can only test whether it is equal. And if can evaluate any type of Boolean expression. That is, switch only looks for a match between the value of an expression and one of its case constants.

2. No two case constants in the same switch can have the same value. Of course, the switch statement and the enclosing outer switch can have the same case constants.

3. A switch statement is usually more efficient than a set of nested ifs.

Related recommendations: "Java Tutorial"

This article is an introduction to the use of Java Switch statements. I hope it will be helpful to friends in need!

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