list排序,根據list中存放物件的某一屬性排序
阿新 • • 發佈:2019-02-04
1.Student的Bean如下:
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中物件的Int型別屬性進行排序
/** * 按照List中的某個Int型別的屬性進行排序 * @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("/////////////排序之後///////////////"); 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中物件的String型別的屬性進行排序
1)方法一:
/** * 按照List中的某個String型別的屬性進行排序 * @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("/////////////排序之後///////////////"); 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來實現,用來執行區分語言環境的String 比較:
/**
* 按照List中的某個String型別的屬性進行排序
* @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("/////////////排序之後///////////////");
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.測試排序的方法
@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中的某個Int型別的屬性進行排序
sortIntMethod(list);
//按照List中的某個String型別的屬性進行排序
sortStringMethod(list);
}
5.結果
1)按照List中物件的Int型別屬性進行排序的結果:
2)按照按照List中物件的String型別的屬性進行排序的結果: