list分别取出相同的元素

[淘气包丶]

一个list存放这样的数据

[{"id":1,"name":张三},{"id":2,"name":李四},{"id":1,"name":李宁},{"id":3,"name":王某},{"id":2,"name":陈某}]

Student对象

public class Student {

  private int id;
  private String name;

  public int getId(){
    return id;
  }

  public void setId(int id){
    this.id=id;
  }

  public String getName(){
    return name;
  }

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

List<Student> students = new ArrayList<Student>();
        Student stu1 = new Student("1", "张三");
        Student stu2 = new Student("2", "李四");
        Student stu3 = new Student("1", "李宁");
        Student stu4 = new Student("3", "王某");
        Student stu5 = new Student("2", "陈某");
        students.add(stu1);
        students.add(stu2);
        students.add(stu3);
        students.add(stu4);
        students.add(stu5);

新建一个list用于存放id相同的元素

for (int i = 0; i < students.length; i++) {
      List<Student> list=new ArrayList<Student>();       //用于存放id相同的元素
    }

大概取出来的list是这样的

第一个list
[{"id":1,"name":张三},{"id":1,"name":李宁},]
第二个list
[{"id":2,"name":李四},{"id":2,"name":陈某}]
第三个list
[{"id":3,"name":王某}]

[qq_39936465]

引用 楼主 guttaoqibao 的回复:

一个list存放这样的数据

public static void main(String[] args) {
		// TODO Auto-generated method stub
		List<Student> students = new ArrayList<Student>();
        Student stu1 = new Student("1", "张三");
        Student stu2 = new Student("2", "李四");
        Student stu3 = new Student("1", "李宁");
        Student stu4 = new Student("3", "王某");
        Student stu5 = new Student("2", "陈某");
        students.add(stu1);
        students.add(stu2);
        students.add(stu3);
        students.add(stu4);
        students.add(stu5);
        sort(students);
	}
	static void sort (List<Student> stus) {
		List<Student> list=new ArrayList<Student>();
		for(int i=0;i<stus.size();i++) {
			if(list.size()==0) {
				list.add(stus.get(i));
				stus.remove(i);
			}else if (stus.get(i).getStudentNo().equals(list.get(0).getStudentNo())) {
				list.add(stus.get(i));
				stus.remove(i);
			}
		}
		System.out.println(list);
		if(stus.size()>0l) {
			sort(stus);
		}
	}

public class Student {
	private String id;
	private String name;

	
	public Student(String studentNo, String name) {
		super();
		this.id = studentNo;
		this.name = name;
	
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getStudentNo() {
		return id;
	}
	public void setStudentNo(String studentNo) {
		this.id = studentNo;
	}
	
	@Override
	public String toString() {
		return "{ \" id\":" + id + ", \"name\":" + name + "}";
	}

}

[qybao]

之前的方法改一下就可以了

List<List<Student>> result = new ArrayList<>(); //最终结果集
for (Student ss : students) { //遍历students
    boolean found = false;
    for (int j=0; j<result.size(); j++) {
        Student s = result.get(j).get(0);
        if (s.getStudentNo().equals(ss.getStudentNo())) { //如果学号
            found = true;
            result.get(j).add(ss); //放到同一个组
            break;
        }
    }
    if (! found) { //如果没有相同的组，则新做成一个组
        List<Student> l = new ArrayList<>();
        l.add(ss);
        result.add(l);
    } 
}

[qybao]

if (s.getStudentNo().equals(ss.getStudentNo())) 改成 if (s.getId().equals(ss.getId()))

[qq_45916051]

groupteam : function(arr){ var map = {}, dest = []; for(var i = 0; i < arr.length; i++) { var ai = arr[i]; if(!map[ai.usercode]) { //依赖分组字段可自行更改！ dest.push({ usercode: ai.usercode, //依赖分组字段可自行更改！ data: [ai] }); map[ai.usercode] = ai; //依赖分组字段可自行更改！ } else { for(var j = 0; j < dest.length; j++) { var dj = dest[j]; if(dj.usercode == ai.usercode) { //依赖分组字段可自行更改！ dj.data.push(ai); break; } } } } return dest; },

[Code ink]