import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
//collection接口
public class coll {
public static void main(String[] args) {
Collection list = new ArrayList();
list.add("a");
list.add("b");
list.add("c");
Iterator it = list.iterator();
while (it.hasNext()){
String str = (String)it.next();
System.out.println(str);
}
}
}
import java.util.ArrayList;
import java.util.List;
public class list {
// list集合
public static void main(String[] args) {
List list = new ArrayList();
list.add("a");
list.add("b");
list.add("c");
int i = (int)(Math.random()*list.size());
System.out.println("随机获取list中的元素"+list.get(i));
list.remove(i);
for (int j = 0; j < list.size(); j++) {
System.out.println(list.get(j));
}
}
}
import java.util.HashSet;
import java.util.Iterator;
public class set {
public static void main(String[] args) {
HashSet set = new HashSet();
set.add("a");
set.add("a");
set.add("b");
Iterator it = set.iterator();
while (it.hasNext()){
System.out.println(it.next());
}
}
}
import java.util.HashMap;
public class map {
public static void main(String[] args) {
HashMap maps = new HashMap();
maps.put(1,"a");
maps.put(2,"aa");
maps.put(3,"aaa");
System.out.println(maps.get(1));
}
}