Java 列表ArrayList排序

迈不过友情╰ 2022-05-08 06:06 210阅读 0赞

对任意类型集合对象进行整体排序，排序时将此接口的实现传递给Collections.sort方法或者Arrays.sort方法排序.   
实现int compare(T o1, T o2);方法，返回正数，零，负数各代表大于，等于，小于。

## 单一条件排序: ##

举例:

List<Student> stus = new ArrayList<>();
            Student stu1 = new Student();
            Student stu2 = new Student();
            Student stu3 = new Student();
            stu1.setName("张三");
            stu1.setAge(30);
    
            stu2.setName("李四");
            stu2.setAge(20);
    
            stu3.setName("王五");
            stu3.setAge(60);
    
            stus.add(stu1);
            stus.add(stu2);
            stus.add(stu3);
    
            //对users按年龄进行排序
            Collections.sort(stus, new Comparator<Student>() {
    
                @Override
                public int compare(Student o1, Student o2) {
                    // 升序
                    //return o1.getAge()-o2.getAge();
                    return o1.getAge().compareTo(o2.getAge());
                    // 降序
                    // return o2.getAge()-o1.getAge();
                    // return o2.getAge().compareTo(o1.getAge());
                }
            });
            // 输出结果
            ...

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## 多条件排序: ##

举例:

List<Student> stus = new ArrayList<>();
            Student stu1 = new Student();
            Student stu2 = new Student();
            Student stu3 = new Student();
            Student stu4 = new Student();
            Student stu5 = new Student();
            Student stu6 = new Student();
    
            stu1.setAge(30);
            stu2.setAge(20);
            stu3.setAge(40);
            stu4.setAge(30);
            stu5.setAge(40);
            stu6.setAge(20);
    
            stu1.setNum(1);
            stu2.setNum(2);
            stu3.setNum(3);
            stu4.setNum(4);
            stu5.setNum(5);
            stu6.setNum(6);
    
            stu1.setName("张三");
            stu2.setName("李四");
            stu3.setName("王五");
            stu4.setName("赵六");
            stu5.setName("陈七");
            stu6.setName("周八");
    
            stus.add(stu1);
            stus.add(stu2);
            stus.add(stu3);
            stus.add(stu4);
            stus.add(stu5);
            stus.add(stu6);
    
            Collections.sort(stus,new Comparator<Student>() {
    
                @Override
                public int compare(Student s1, Student s2) {
                    int flag;
                    // 首选按年龄升序排序
                    flag = s1.getAge()-s2.getAge();
                    if(flag==0){
                        // 再按学号升序排序
                        flag = s1.getNum()-s2.getNum();
                    }
                    return flag;
                }
            });
    
            System.out.println("年龄       学号       姓名  ");
            for(Student s : stus){
                System.out.println(s.getAge()+"   "+s.getNum()+"   "+s.getName());
            }

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输出结果:  
![这里写图片描述][SouthEast]

## 自定义条件排序 ##

String[] order = {"语文","数学","英语","物理","化学","生物","政治","历史","地理","总分"};
            final List<String> defiderOrder = Arrays.asList(order);
            List<String> list = new ArrayList<>();
            list.add("总分");
            list.add("英语");
            list.add("政治");
            list.add("总分");
            list.add("数学");
            Collections.sort(list,new Comparator<String>() {
    
                @Override
                public int compare(String o1, String o2) {
                    int io1 = defiderOrder.indexOf(o1);
                    int io2 = defiderOrder.indexOf(o2);
                    return io1-io2;
                }
            });
    
            for(String s:list){
                System.out.print(s+"   ");
            }

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输出结果:  
![这里写图片描述][SouthEast 1]

CSDN 原文：https://blog.csdn.net/lx\_nhs/article/details/78871295?

[SouthEast]: /images/20220508/8f25de4acf3c42669a69922cb202eaa8.png
[SouthEast 1]: /images/20220508/5da5c40bd1bc48f8b519772f3ed6ca42.png