From fd0b9726ca2794fc9615233069538548a97f9d82 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E2=80=9Cidpeng=E2=80=9D?= <630606938@qq.com>
Date: Mon, 30 Aug 2021 22:24:48 +0800
Subject: [PATCH] =?UTF-8?q?=E5=85=88x=E5=86=8Dy=EF=BC=8C=E4=BB=8E=E5=B0=8F?=
 =?UTF-8?q?=E5=88=B0=E5=A4=A7=E7=9A=84=E9=A1=BA=E5=BA=8F=E6=8E=92=E5=BA=8F?=
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---
 .../com/github/hcsp/polymorphism/Point.java   | 26 +++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/src/main/java/com/github/hcsp/polymorphism/Point.java b/src/main/java/com/github/hcsp/polymorphism/Point.java
index 780e6b1..63bbb45 100644
--- a/src/main/java/com/github/hcsp/polymorphism/Point.java
+++ b/src/main/java/com/github/hcsp/polymorphism/Point.java
@@ -2,12 +2,15 @@
 
 import java.io.IOException;
 import java.util.Arrays;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
-public class Point {
+public class Point implements Comparable<Point> {
 
     private final int x;
     private final int y;
+
     // 代表笛卡尔坐标系中的一个点
     public Point(int x, int y) {
         this.x = x;
@@ -53,7 +56,10 @@ public String toString() {
 
     // 按照先x再y，从小到大的顺序排序
     // 例如排序后的结果应该是 (-1, 1) (1, -1) (2, -1) (2, 0) (2, 1)
-    public static List<Point> sort(List<Point> points) {}
+    public static List<Point> sort(List<Point> points) {
+        Collections.sort(points);
+        return points;
+    }
 
     public static void main(String[] args) throws IOException {
         List<Point> points =
@@ -65,4 +71,20 @@ public static void main(String[] args) throws IOException {
                         new Point(2, -1));
         System.out.println(Point.sort(points));
     }
+
+    @Override
+    public int compareTo(Point that) {
+        if (this.x < that.x) {
+            return -1;
+        } else if (this.x > that.x) {
+            return 1;
+        } else {
+            if (this.y < that.y) {
+                return -1;
+            } else if (this.y > that.y) {
+                return 1;
+            }
+            return 0;
+        }
+    }
 }