List集合按某个字段排序

packagewjtest_01;

importjava.util.ArrayList;

importjava.util.Collections;

importjava.util.Comparator;

importjava.util.List;

publicclassListSort{

@SuppressWarnings("unchecked")

publicstaticvoidmain(String[] args){

List list =newArrayList();

// 创建3个学生对象，年龄分别是20、19、21，并将他们依次放入List中

Student s1 =newStudent();

s1.setAge(20);

s1.setUsable(true);

Student s2 =newStudent();

s2.setAge(19);

s2.setUsable(true);

Student s3 =newStudent();

s3.setAge(21);

s3.setUsable(false);

list.add(s1);

list.add(s2);

list.add(s3);

System.out.println("排序前："+ list);

Collections.sort(list,newComparator() {

@Override

publicintcompare(Student o1, Student o2){

// 按照学生的年龄进行升序排列

if(o1.getAge() > o2.getAge()) {

return1;

}

if(o1.getAge() == o2.getAge()) {

return0;

}

return-1;

}

});

System.out.println("升序排序后："+ list);

Collections.sort(list,newComparator() {

publicintcompare(Student o1, Student o2){

// 按照学生的年龄进行降序排列

if(o1.getAge() > o2.getAge()) {

return-1;

}

if(o1.getAge() == o2.getAge()) {

return0;

}

return1;

}

});

System.out.println("降序排序后："+ list);

Boolean b1 =true;// 创建Boolean对象1

Boolean b2 =false;// 创建Boolean对象0

Boolean b3 =true;// 创建Boolean对象1

System.out.println(b1);

inti;

i = b1.compareTo(b2);// b1和b2进行比较 

System.out.println(i);//1-0

i = b2.compareTo(b1);// b2和b1进行比较

System.out.println(i);//0-1

i = b1.compareTo(b3);// b1和b3进行比较

System.out.println(i);//1-1

}

}

classStudent{

privateintage;

privateBoolean isUsable;

publicintgetAge(){

returnage;

    } 

publicBooleanisUsable(){

returnisUsable;

}

publicvoidsetUsable(Boolean isUsable){

this.isUsable = isUsable;

}

publicvoidsetAge(intage){

this.age = age;

    } 

@Override

publicStringtoString(){

returngetAge()+"";

    } 

}