Java中switch的四种用法-Toy模板网

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总共有四种不同形式的switch。两种是switch语句，两种是switch表达式，表达式会生成一个值。switch表达式没有“直通式”行为。

表达式，无直通行为

int numLetters
numLetters = switch(seasonName){
	case "Spring" ->{
		System.out.println("spring time");
		yield 6;
		}
	case "Summer","Winter" -> 6;
	case "Fall" -> 4;
	default -> -1;
}

语句，无直通行为

switch(seasonName){
	case "Spring" -> {
		System.out.println("spring time");
		numLetters = 6;
		}
	case "Summer","Winter" -> numLetters = 6;
	case "Fall" -> numLetters = 4;
	default -> numLetters = -1;
}

表达式，有直通行为（Java 14引入）

int numLetters
numLetters = switch(seasonName){
	case "Spring":
		System.out.println("spring time");
	case "Summer","Winter":
		yield 6;
	case "Fall":
		yield 4;
	default:
		yield -1;
}

语句，有直通行为（“经典”形式）

switch(seasonName){
	case "Spring":
		System.out.println("spring time");
	case "Summer","Winter":
		numLetters = 6;
		break;
	case "Fall":
		numLetters = 4;
		break;
	default:
		numLetters = -1;
}