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Switch.java
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104 lines (90 loc) · 3.29 KB
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package io.itjun.basic.java17;
import com.google.gson.Gson;
public class Switch {
record FavoriteFruit(String name, FruitType fruit) {
}
public static void main(String[] args) {
FavoriteFruit f1 = new FavoriteFruit("itjun", FruitType.APPLE);
System.out.println(new Gson().toJson(f1));
FavoriteFruit f2 = new FavoriteFruit("john", FruitType.ORANGE);
System.out.println(new Gson().toJson(f2));
// oldStyleWithoutBreak(FruitType.APPLE);
// withSwitchExpression(FruitType.APPLE);
// withSwitchExpression(FruitType.AVOCADO);
// withYield(FruitType.APPLE);
oldStyleWithYield(FruitType.APPLE);
}
private static void oldStyleWithoutBreak(FruitType fruit) {
System.out.println("""
***************************
* Old style without break *
***************************""");
switch (fruit) {
case APPLE, PEAR:
System.out.println("Common fruit");
case ORANGE, AVOCADO:
System.out.println("Exotic fruit");
default:
System.out.println("Undefined fruit");
}
}
public enum FruitType {
APPLE, PEAR, ORANGE, AVOCADO;
}
private static void withSwitchExpression(FruitType fruit) {
System.out.println("""
**************************
* With switch expression *
**************************""");
switch (fruit) {
case APPLE, PEAR -> System.out.println("Common fruit");
case ORANGE, AVOCADO -> System.out.println("Exotic fruit");
default -> System.out.println("Undefined fruit");
}
}
private static void withReturnValue(FruitType fruit) {
System.out.println("""
*********************
* With return value *
*********************""");
String text = switch (fruit) {
case APPLE, PEAR -> "Common fruit";
case ORANGE, AVOCADO -> "Exotic fruit";
default -> "Undefined fruit";
};
System.out.println(text);
}
/**
* 当您需要在 case 中做不止一件事情时，您会怎么做？
* 在这种情况下，您可以使用方括号来表示 case 块，并在返回值时使用关键字 yield。
*/
private static void withYield(FruitType fruit) {
System.out.println("""
**************
* With yield *
**************""");
String text = switch (fruit) {
case APPLE, PEAR -> {
System.out.println("the given fruit was: " + fruit);
yield "Common fruit";
}
case ORANGE, AVOCADO -> "Exotic fruit";
default -> "Undefined fruit";
};
System.out.println(text);
}
private static void oldStyleWithYield(FruitType fruit) {
System.out.println("""
************************
* Old style with yield *
************************""");
System.out.println(switch (fruit) {
case APPLE, PEAR:
yield "Common fruit";
case ORANGE, AVOCADO:
yield "Exotic fruit";
default:
yield "Undefined fruit";
});
}
}