最近工作中遇到对list排序的问题,使用Collection.sort()
下边是我自己做的练习,记录下
package com.junit.test; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; import java.util.Iterator; import java.util.List; public class CollectionsTest { public static void main(String[] args) { CollectionsTest c = new CollectionsTest(); List<Student> stList = new ArrayList<Student>(); Student s1 = c.new Student(); s1.setAge("33"); s1.setName("groupB"); s1.setSex("nan4"); Student s5 = c.new Student(); s5.setAge("77"); s5.setName("groupB"); s5.setSex("nan4"); Student s2 = c.new Student(); s2.setAge("22"); s2.setName("groupC"); s2.setSex("nan1"); Student s3 = c.new Student(); s3.setAge("13"); s3.setName("groupA"); s3.setSex("nan2"); Student s4 = c.new Student(); s4.setAge("17"); s4.setName("groupG"); s4.setSex("nan6"); stList.add(s1); stList.add(s2); stList.add(s3); stList.add(s4); stList.add(s5); Iterator iter = stList.iterator(); while(iter.hasNext()){ Student st = (Student)iter.next(); System.out.println(st.getName()+" "+st.getAge()+" " +st.getSex()); } System.out.println("---------------------------------------------"); Collections.sort(stList, c.new Compartor1()); Iterator iter1 = stList.iterator(); while(iter1.hasNext()){ Student st1 = (Student)iter1.next(); System.out.println(st1.getName()+" "+st1.getAge()+" " +st1.getSex()); } } public class Compartor1 implements Comparator<Student>{ public int compare(Student o1, Student o2) { String name1 = o1.getName(); String name2 = o2.getName(); //先按name升序 if(name1.compareTo(name2)>0){ return 1; }else if(name1.compareTo(name2)<0){ return -1; } else{ //再按age降序排列 String age1 = o1.getAge(); String age2 = o2.getAge(); if(age1.compareTo(age2)>0){ return -1; }else if(age1.compareTo(age2)<0){ return 1; } } return 0; } } public class Student{ public String name; public String age; public String sex; public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAge() { return age; } public void setAge(String age) { this.age = age; } public String getSex() { return sex; } public void setSex(String sex) { this.sex = sex; } } }
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