1.TreeSet的add()方法:
public class TreeSetTest3
{
public staic void main(String[] args)
{
TreeSet set = new TreeSet();
set.add(“C”);
set.add(“A”);
set.add(“B”);
set.add(“E”);
set.add(“F”);
set.add(“D”);
for(Iterator iter = set.iterator();iter.hasNext(); )
{
String value = (String)iter.next();
System.out.println(value);
}
}
}
class MyComparator implements Comparator
{
public int compare(Object arg0,Object arg1)
{
String s1 = (String)arg0;
String s2 = (String)arg1;
return s2.compareTo(s1);
}
}
2.自定义comparator()方法,实现将自定义类的对象添加到TreeSet对象中.
import java.util.Comparator;
import java.util.Iterator;
import java.util.TreeSet;
public class TreeSetTest2 {
public static void main(String[] args) {
Person p1 = new Person(10);
Person p2 = new Person(20);
Person p3 = new Person(30);
Person p4 = new Person(40);
TreeSet set1 = new TreeSet(new Person());
set1.add(p1);
set1.add(p2);
set1.add(p3);
set1.add(p4);
for(Iterator iter = set1.iterator();iter.hasNext();){
System.out.println(iter.next());
}
}
}
class Person implements Comparator{
int score;
public Person(){
};
public Person(int score) {
this.score = score;
}
public String toString() {
return String.valueOf(this.score);
}
public int compare(Object arg0, Object arg1) {
Person p1 = (Person)arg0;
Person p2 = (Person)arg1;
if(p1.score>p2.score)
return 1;
if(p1.score<p2.score)
return -1;
if(p1.score == p2.score)
return 0;
return 0;
}
}
3.类Collections是Collection接口的一个实现类其操作对象时集合.
包括static方法: