List 利用compare 排序

一、在對象中實現Comparable接口

public class Student2 implements Comparable<Student2> {
    private String name;

    private int age;

    private int sex;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getSex() {
        return sex;
    }

    public void setSex(int sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "Student1{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", sex=" + sex +
                '}';
    }

    @Override
    public int compareTo(Student2 o) {
        return this.getAge()-o.getAge();
    }
}

在排序的地方使用如下代碼：

Collections.sort(student1List);

    @Test
    public void testSort2(){
        List<Student2> student1List = new ArrayList<Student2>();
        Student2 s1 = new Student2();
        s1.setName("z3");
        s1.setAge(20);
        s1.setSex(0);

        Student2 s2 = new Student2();
        s2.setName("l4");
        s2.setAge(15);
        s2.setSex(1);

        Student2 s3 = new Student2();
        s3.setName("w5");
        s3.setAge(23);
        s3.setSex(1);

        Student2 s4 = new Student2();
        s4.setName("z6");
        s4.setAge(19);
        s4.setSex(0);

        student1List.add(s1);
        student1List.add(s2);
        student1List.add(s3);
        student1List.add(s4);

        Collections.sort(student1List);

        for (Student2 s:student1List) {
            System.out.println("student:"+s.toString());
        }
    }

輸出：

二、在排序時自己重寫compareTo接口

實體類

public class Student1 {
    private String name;

    private int age;

    private int sex;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public int getSex() {
        return sex;
    }

    public void setSex(int sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "Student1{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", sex=" + sex +
                '}';
    }
}

使用時採用如下方式：

Collections.sort(student1List, new Comparator<Student1>() {
    @Override
    public int compare(Student1 o1, Student1 o2) {
        return o1.getName().compareTo(o2.getName());
    }
});

    @Test
    public void testSort1(){
        List<Student1> student1List = new ArrayList<Student1>();
        Student1 s1 = new Student1();
        s1.setName("z3");
        s1.setAge(20);
        s1.setSex(0);

        Student1 s2 = new Student1();
        s2.setName("l4");
        s2.setAge(15);
        s2.setSex(1);

        Student1 s3 = new Student1();
        s3.setName("w5");
        s3.setAge(23);
        s3.setSex(1);

        Student1 s4 = new Student1();
        s4.setName("z6");
        s4.setAge(19);
        s4.setSex(0);

        student1List.add(s1);
        student1List.add(s2);
        student1List.add(s3);
        student1List.add(s4);

        Collections.sort(student1List, new Comparator<Student1>() {
            @Override
            public int compare(Student1 o1, Student1 o2) {
                return o1.getName().compareTo(o2.getName());
            }
        });

        for (Student1 s:student1List) {
            System.out.println("student:"+s.toString());
        }
    }

輸出：