Java实现排序的方法--List，数组排序。【自定义】继承Comparable和Comparator

骑猪看日落 2021-09-15 02:04 381阅读 0赞

（一）list和数组

①List默认排序代码：

public static void main(String[] args) {
        List<String> list = new ArrayList<>();
        list.add("阿a里 ");
        list.add("不b安定 ");
        list.add("嘻x嘻 ");
        list.add("一y一 ");
        list.add("传c递 ");
        list.add("东d西 ");
        list.add("耳e朵 ");
        list.add("分f数 ");
    
        for (int i=0;i<list.size();i++){
            System.out.print(list.get(i));
        }
    
        //降序【以现有list的顺序----从后往前输出 】 System.out.println(" 降序");
    
        Collections.reverse(list);
        for (int i=0;i<list.size();i++){
            System.out.print(list.get(i));
        }
        //依照list 现在顺序---从前往后读 一y一 不b安定 东d西 传c递 分f数 嘻x嘻 耳e朵 阿a里 System.out.println(" 升序");
        Collections.sort(list);
        for (int i=0;i<list.size();i++){
            System.out.print(list.get(i));
        }
        System.out.println("按照汉语拼音排序");
        //排序 abcdefg这么来的【首字母按照汉语拼音来的】 Collections.sort(list,Collator.getInstance(Locale.CHINA));
        for (int i=0;i<list.size();i++){
            System.out.print(list.get(i));
        }
    
    }

②：数组：

String[] names = {
      "阿a里", "把b把", "阿a里", "得d到", "额e额", "得d到","阿b里"};
    //应该是根据ASCII码这么来的 Arrays.sort(names);
    System.out.println(Arrays.toString(names));
    Arrays.sort(names,Collator.getInstance(Locale.CHINA));
    //根据中文字母表排序，先比较第一个字母拼音，再比较第二个字母拼音。 System.out.println(Arrays.toString(names));

（二）自定义排序：

①实现Comparable接口，类内设比较项。

public class Test1 implements Comparable {
        /* * 1.实现Comparable接口 * 重写int compareTo（Object o）方法 * */ private String name;
        private Integer age;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Test1(String name, Integer age) {
            this.name = name;
            this.age = age;
        }
    
        @Override
        public int compareTo(Object o) {
            Test1 sutdent = (Test1) o;
            int age1 = sutdent.getAge();
            return this.age.compareTo(age1);
        }
    
        public static void main(String[] args) {
            List<Test1> students = new ArrayList<>();
            Test1 s1 = new Test1("十一", 11);
            Test1 s2 = new Test1("十二", 12);
            Test1 s3 = new Test1("十三", 13);
            Test1 s4 = new Test1("十四", 14);
            students.add(s1);
            students.add(s4);
            students.add(s2);
            students.add(s3);
            students.add(s2);
            //reverse 仅仅只是反转 Collections.reverse(students);
            for (Test1 t : students) {
                System.out.print(t.getAge() + " ");
            }
    
            //调用自己的类的int属性进行比较 Collections.sort(students);
    
            for (Test1 t : students) {
                System.out.print(t.getAge() + " ");
            }
            System.out.println(" ");
    
        }
    
    }

②实现 Comparator接口， 类外设比较项。

public class Test1 implements Comparator<Test1> {
        /* * 1.实现Comparable接口 * 重写int compareTo（Object o）方法 * */ private String name;
        private Integer age;
    
        public String getName() {
            return name;
        }
    
        public void setName(String name) {
            this.name = name;
        }
    
        public Integer getAge() {
            return age;
        }
    
        public void setAge(Integer age) {
            this.age = age;
        }
    
        public Test1() {
        }
    
        public Test1(String name, Integer age) {
            this.name = name;
            this.age = age;
        }
        @Override
        public int compare(Test1 o1, Test1 o2) {
            return o1.age.compareTo(o2.age);
        }
    
        public static void main(String[] args) {
            Test1 s1=new Test1("小1",11);
            Test1 s3=new Test1("小3",13);
            Test1 s2=new Test1("小2",12);
            Test1 s4=new Test1("小4",14);
            //Array.adList就是固定长度集合。 List<Test1> students=Arrays.asList(s1,s3,s2,s4);
            for (Test1 s:students){
                System.out.print(s.age+" ");
            }
            System.out.println("排序后");
            Collections.sort(students,new Test1());
            for (Test1 s:students){
                System.out.print(s.age+" ");
            }

}
        }