Question

java如何对ArrayList中对象按照该对象某属性排序

Answer 1

if(!s1.name.equals(s2.name)){ return s2.name.compareTo(s1.name);}else{//姓名也相同则按学号排序 return s2.id-s1.id;}}}};Student stu1 = new Student (1,"zhangsan","male",28,"cs"); Student stu2 = new Student (2,"lisi","female",19,"cs"); Student stu3 = new Student (3,"wangwu","male",22,"cs"); Student stu4 = new Student (4,"zhaoliu","female",17,"cs"); Student stu5 = new Student (5,"jiaoming","male",22,"cs"); ArrayList List = new ArrayList(); List.add(stu1); List.add(stu2); List.add(stu3); List.add(stu4); List.add(stu5); //这里就会自动根据规则进行排序 Collections.sort(List,comparator); display(List);} static void display(ArrayList lst){ for(Student s:lst) System.out.println(s);}} class Student{int age;int id;String gender; String name;String cs;Student(int id,String name,String gender,int age,String cs){ this.age=age; this.name=name; this.gender=gender; this.id=id; return id+" "+name+" "+gender+" "+age+" "+cs;}} 2.添加 Comparable 接口，重写 compareTo 方法。然后你可以用 TreeSet 结构进行排序。它会自动排序。