List集合数据排序使用比较器
开发中有时候需要自己封装分页排序时,List如何对某一属性排序呢,分享一个小实例,大家共勉,希望能对大家有用,请多多指教。
1.Student的Bean如下:
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public
class Student {
private int
age;
private String name;
private String weight;
public String getWeight() {
return weight;
}
public void
setWeight(String weight) {
this .weight = weight;
}
public int
getAge() {
return age;
}
public void
setAge( int age) {
this .age = age;
}
public String getName() {
return name;
}
public void
setName(String name) {
this .name = name;
}
} |
2.按照List中对象的Int类型属性进行排序
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/** * 按照List中的某个Int类型的属性进行排序
* @param list
*/
@SuppressWarnings ( "unchecked" )
public
static void sortIntMethod(List list){
Collections.sort(list, new
Comparator(){
@Override
public int
compare(Object o1, Object o2) {
Student stu1=(Student)o1;
Student stu2=(Student)o2;
if (stu1.getAge()>stu2.getAge()){
return 1 ;
} else if (stu1.getAge()==stu2.getAge()){
return 0 ;
} else {
return - 1 ;
}
}
});
System.out.println( "/////////////排序之后///////////////" );
for ( int i= 0 ;i<list.size();i++){
Student st=(Student)list.get(i);
System.out.println( "st.age=" +st.getAge()+ ",st.name=" +st.getName());
}
} |
3.按照List中对象的String类型的属性进行排序
1)方法一:
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/** * 按照List中的某个String类型的属性进行排序
* @param list
*/
@SuppressWarnings ( "unchecked" )
public
static void sortStringMethod(List list){
Collections.sort(list, new
Comparator(){
@Override
public int
compare(Object o1, Object o2) {
Student stu1=(Student)o1;
Student stu2=(Student)o2;
return stu1.getName().compareTo(stu2.getName());
}
});
System.out.println( "/////////////排序之后///////////////" );
for ( int i= 0 ;i<list.size();i++){
Student st=(Student)list.get(i);
System.out.println( "st.age=" +st.getAge()+ ",st.name=" +st.getName());
}
} |
2)方法二:
使用java.text.RuleBasedCollator来实现,用来执行区分语言环境的String 比较:
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/** * 按照List中的某个String类型的属性进行排序
* @param list
*/
@SuppressWarnings ( "unchecked" )
public static
void sortByRuleBasedCollator(List list){
Collections.sort(list, new
Comparator(){
@Override
public int
compare(Object o1, Object o2) {
return ((java.text.RuleBasedCollator)java.text.Collator.getInstance(java.util.Locale.CHINA)).compare(((Student)o1).getName(),
((Student)o2).getName());
}
});
System.out.println( "/////////////排序之后///////////////" );
for ( int i= 0 ;i<list.size();i++){
Student st=(Student)list.get(i);
System.out.println( "st.age=" +st.getAge()+ ",st.name=" +st.getName());
}
}
|
4.测试排序的方法
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@SuppressWarnings ( "unchecked" )
public
static void main(String[] args) {
ArrayList list= new ArrayList();
Student t1= new Student();
t1.setAge( 35 );
t1.setName( "wanglei" );
list.add(t1);
Student t2= new Student();
t2.setAge( 4 );
t2.setName( "lisi" );
list.add(t2);
Student t3= new Student();
t3.setAge( 56 );
t3.setName( "zhonghua" );
list.add(t3);
Student t4= new Student();
t4.setAge( 39 );
t4.setName( "waanglei" );
list.add(t4);
System.out.println( "/////////////排序之前///////////////" );
for ( int i= 0 ;i<list.size();i++){
Student st=(Student)list.get(i);
System.out.println( "st.age=" +st.getAge()+ ",st.name=" +st.getName());
}
//按照List中的某个Int类型的属性进行排序
sortIntMethod(list);
//按照List中的某个String类型的属性进行排序
sortStringMethod(list);
} |
5.结果
还有一种方式是借用于集合的方法
Collections.sort(List<T> list);
此方法排序出来的结果是从小到大 (我测试过整型和时间类型)