Compareable接口

 

重写 compareTo方法如下：

public int compareTo(Object o) {Name n = (Name) o;int lastCmp = secondName.compareTo(n.secondName);return(lastCmp!=0 ? lastCmp:firstName.compareTo(n.firstName));}

 

 

完整代码如下

 

import java.util.List;
import java.util.LinkedList;
import java.util.Collections;
public class Test {public static void main(String[] args) {List l1 = new LinkedList();l1.add(new Name("Karl","M"));l1.add(new Name("Steven","Lee"));l1.add(new Name("John","O"));l1.add(new Name("Tom","M"));System.out.println(l1);Collections.sort(l1);System.out.println(l1);/*Set s = new HashSet();s.add("hello");s.add("world");s.add(new Name("f1","11"));s.add(new Integer(100));*//*s.add("hello");s.add("hello");*///Set /*Set s1 = new HashSet();Set s2 = new HashSet();s1.add("a");s1.add("b");s1.add("c");s2.add("d");s2.add("a");s2.add("b");Set sn = new HashSet(s1);sn.retainAll(s2);Set su = new HashSet(s1);su.addAll(s2);System.out.println(sn);System.out.println(su);*//*Collection c = new HashSet();c.add("hello");c.add(new Name("f1","11"));c.add(new Name("f2","12"));c.add(new Name("f3","13"));c.add(new Integer(100));c.remove("hello");c.remove(new Integer(100));Iterator i = c.iterator();while(i.hasNext()) {Name n = (Name)i.next();System.out.print(n.getfirstName()+" ");}*//*System.out.println(c.remove(new Name("f1","11")));System.out.println(c);*/}
}
class Name implements Comparable {private String firstName,secondName;public Name(String firstName,String secondName) {this.firstName = firstName;this.secondName = secondName;}public String getfirstName() {return firstName;}public String getsecondName() {return secondName;}public String toString() {return firstName+" "+secondName;}public boolean equals(Object obj) {if(obj instanceof Name) {Name name = (Name) obj;return (firstName.equals(name.firstName))&&(secondName.equals(name.secondName));}return super.equals(obj);}public int hashCode() {return firstName.hashCode();}public int compareTo(Object o) {Name n = (Name) o;int lastCmp = secondName.compareTo(n.secondName);return(lastCmp!=0 ? lastCmp:firstName.compareTo(n.firstName));}
}