s-day02-Collections里面的sort方法以及Comparable接口

s-day03/src/com/inmind/collections04/Demo14.java

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+package com.inmind.collections04;
+
+import java.util.ArrayList;
+import java.util.Collections;
+
+/*
+static <T extends Comparable<? super T>> void sort(List<T> list) 根据其元素的自然排序，按照升序排列指定的列表。
+ */
+public class Demo14 {
+    public static void main(String[] args) {
+        //整数的自然排序，默认升序
+        ArrayList<Integer> lists = new ArrayList<>();
+        Collections.addAll(lists, 111, 22, 32, 4, 555);
+        System.out.println(lists);
+        //对集合进行排序
+        Collections.sort(lists);
+        System.out.println(lists);
+        System.out.println("-------------------------------------");
+        //字符串的默认排序，按照字典排序，按ASCII码值
+        ArrayList<String> strs = new ArrayList<>();
+        Collections.addAll(strs, "ab", "ba", "aa", "ca", "ac","bb");
+        System.out.println(strs);
+        //对集合进行排序
+        Collections.sort(strs);
+        System.out.println(strs);
+
+        //自定义类的排序(Student)
+        ArrayList<Student> students = new ArrayList<>();
+        students.add(new Student("张三1", 18,88));
+        students.add(new Student("张三2", 18,90));
+        students.add(new Student("张三3", 18,93));
+        students.add(new Student("张三4", 18,39));
+        System.out.println(students);
+        //注意：Collections.sort排序时，传入的集合的内容，必须拥有自然排序功能（实现Comparable）
+        Collections.sort(students);
+        System.out.println(students);
+
+    }
+}

s-day03/src/com/inmind/collections04/Student.java

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+package com.inmind.collections04;
+
+public class Student implements Comparable<Student>{
+    String name;
+    int age;
+    int score;
+
+    public Student(String name, int age, int score) {
+        this.name = name;
+        this.age = age;
+        this.score = score;
+    }
+
+    @Override
+    public String toString() {
+        return "Student{" +
+                "name='" + name + '\'' +
+                ", score=" + score +
+                '}';
+    }
+
+    /*
+    排序口诀:
+            我(this)-它(参数o):升序
+            它-我:降序
+     */
+    @Override
+    public int compareTo(Student o) {
+//        return this.score - o.score; //升序
+       /* if (this.score > o.score) {
+            return -1;
+        } else if (this.score < o.score) {
+            return 1;
+        } else {
+            return 0;
+        }*/
+        return o.score - this.score;
+    }
+}