Java14：模式匹配：instanceof

示例1

  public static void main(String[] args) {
        Object obj1 = "好好学习，天天向上";
        //传统代码
        if (obj1 instanceof String) {
            String str = (String) obj1;
            System.out.println(str);
        } else {
            System.out.println("不是字符串类型");
        }

        //使用新特性
        //如果是String类型，直接将其值赋给变量str，该str的作用域仅限于if语句
        if (obj1 instanceof String str) {
            System.out.println(str);
        } else {
            System.out.println("不是字符串类型");
        }
    }

示例2

public class Point {
    private double x;
    private double y;

    @Override
    public boolean equals(Object obj) {
        return obj instanceof Point other && this.x == other.x && this.y == other.y;
    }
}