java list排序

1.java提供的默认list排序方法

List list = new ArrayList();list.add(\"刘媛媛\"); list.add(\"王硕\"); list.add(\"李明\"); list.add(\"刘迪\"); list.add(\"刘布\");

//升序

Collections.sort(list,Collator.getInstance(java.util.Locale.CHINA));//注意：是根据的汉字的拼音的字母排序的，而不是根据汉字一般的排序方法 for(int i=0;iSystem.out.print(list.get(i)); }

System.out.println(\"\");

//降序

Collections.reverse(list);//不指定排序规则时，也是按照字母的来排序的 for(int i=0;iSystem.out.print(list.get(i)); }

输出结果：

李明刘布刘迪刘媛媛王硕 王硕刘媛媛刘迪刘布李明

2.自定义的排序规则：

第一种是model类实现Comparable接口，重写重写int compareTo(Object o)方法 model类：

public class StudentDTO implements Comparable {

private String name; private int age;

public String getName() {

return name; }

public void setName(String name) {

this.name = name; }

public ObjType getType() {

return type; }

public void setAge(int age) {

this.age= age; }

@Override

public int compareTo(Object o) {

StudentDTO sdto = (StudentDTO)o;

int otherAge = sdto.getAge();

// note: enum-type's comparation depend on types' list order of enum method

// so, if compared property is enum-type ,then its comparationfollow ObjEnum.objType order

return this.age.compareTo(otherAge); } }

主方法：

public static void main(String[] args) {

List studentList = new ArrayList(); StudentDTO s1 = new StudentDTO ();

s.setName(\"yuanyuan\"); s.setAge(22); studentList.add(s1);

StudentDTO s1 = new StudentDTO (); s.setName(\"lily\"); s.setAge(23); studentList.add(s2);

Collections.sort(studentList); //按照age升序 22，23， Collections.reverse(studentList); //按照age降序 23,22

}

第二种是比较器类实现Comparator接口，重写int compare(Object o1, Object o2)方法； model类：

public class StudentDTO implements Comparable {

private String name; private int age; public String getName() {

return name; }

public void setName(String name) {

this.name = name; }

public ObjType getType() {

return type; }

public void setAge(int age) {

this.age= age; } }

比较器类：

class MyCompartor implements Comparator {

@Override

public int compare(Object o1, Object o2) {

StudentDTO sdto1= (StudentDTO )o1; StudentDTO sdto2= (StudentDTO )o2;

return sdto1.getAge.compareTo(stdo2.getAge()) } }

主方法：

public static void main(String[] args) {

List studentList = new ArrayList(); StudentDTO s1 = new StudentDTO (); s.setName(\"yuanyuan\"); s.setAge(22); studentList.add(s1);

StudentDTO s1 = new StudentDTO (); s.setName(\"lily\"); s.setAge(23); studentList.add(s2);

MyComparetor mc = new MyComparetor();

Collections.sort(studentList,mc); //按照age升序 22，23， Collections.reverse(studentList,mc); //按照age降序 23,22 }