实现一个类Pair，包含：两个成员变量x和y，构造方法，重写equals

方法和toString方法。

public class Pair {
    private int x;
    private int y;

    public Pair(int x, int y) {
        this.x = x;
        this.y = y;
    }

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

    @Override
    public String toString() {
        return "(" + this.x + ", " + this.y + ")";
    }
}

测试代码：

public class PairTest {
    public static void main(String[] args) {
        Pair p1 = new Pair(1, 2);
        Pair p2 = new Pair(1, 2);
        Pair p3 = new Pair(2, 1);

        System.out.println(p1.equals(p2));  // true
        System.out.println(p1.equals(p3));  // false

        System.out.println(p1.toString());  // (1, 2)
        System.out.println(p3.toString());  // (2, 1)
    }
}