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import java.util.*;
public class IteratorTest
{
public static void main(String[] args)
{
Collection books = new HashSet();
books.add(new String("Java EE"));
books.add(new String("IOS"));
books.add(new String("Android"));
System.out.println(books);
Iterator it = books.iterator();
String b = (String)it.next(); //①
b = "aaa";
System.out.println(books);
}
}
import java.util.*;
public class Test {
private String a;
public Test(String a){
this.a = a;
}
public String toString(){
return "["+a+"]";
}
public static void main(String[] args){
HashSet hs = new HashSet();
hs.add(new Test("java"));
hs.add(new Test("c++"));
hs.add(new Test("ruby"));
System.out.println(hs);
//取出第一个元素
Iterator it = hs.iterator();
Test first = (Test)it.next();
//为第一个元素的a实例变量赋值
first.a = "C#";
System.out.println(hs);
}
}