java 对象List按照多个字段进行排序

新建一个对象

[code]public class A {

String a;
String b;

public A() {
}

public A(String a, String b) {
this.a = a;
this.b = b;
}

public String getA() {
return a;
}

public void setA(String a) {
this.a = a;
}

public String getB() {
return b;
}

public void setB(String b) {
this.b = b;
}

@Override
public String toString() {
return "A{" +
"a='" + a + '\'' +
", b='" + b + '\'' +
'}';
}
}

进行排序

[code]import java.text.ParseException;
import java.util.*;

public class Test01 {
public static void main(String[] args) throws ParseException {
//新建9个A对象
A a = new A("11","23");
A a1 = new A("15","21");
A a2 = new A("15","22");
A a3 = new A("13","24");
A a4 = new A("16","22");
A a5 = new A("18","28");
A a6 = new A("12","29");
A a7 = new A("19","27");
A a8 = new A("11","21");

//将对象放入aList集合中
List<A> aList = new ArrayList<>();
aList.add(a);
aList.add(a1);
aList.add(a2);
aList.add(a3);
aList.add(a4);
aList.add(a5);
aList.add(a6);
aList.add(a7);
aList.add(a8);

System.out.println(aList);
//输出结果:[A{a='11', b='23'}, A{a='15', b='21'}, A{a='15', b='22'}, A{a='13', b='24'}, A{a='16', b='22'}, A{a='18', b='28'}, A{a='12', b='29'}, A{a='19', b='27'}, A{a='11', b='21'}]

Comparator<A> bya = Comparator.comparing(A::getA);//按照a升序
Comparator<A> byb = Comparator.comparing(A::getB);//按照b升序

Collections.sort(aList,bya.thenComparing(byb));//将aList按照a字段先升序再按照B字段进行升序排列

System.out.println(aList);
//输入结果:[A{a='11', b='21'}, A{a='11', b='23'}, A{a='12', b='29'}, A{a='13', b='24'}, A{a='15', b='21'}, A{a='15', b='22'}, A{a='16', b='22'}, A{a='18', b='28'}, A{a='19', b='27'}]

}