JAVA-Map集合中的keySethe和entry取值方法

<span style="font-size:18px;"><strong>import java.util.Iterator;
import java.util.Set;
import java.util.TreeMap;
import java.util.Map.Entry;

public class Demo {

public static void main(String[] args) {

TreeMap<Integer,String> tm = new TreeMap<Integer,String>();
tm.put(20,"张三");
tm.put(25,"李四");
tm.put(22,"赵六");
tm.put(21,"王五");

System.out.println("--------增强for循环:keySet方法-------");
//增强for循环:keySet方法
for(Integer k : tm.keySet()){
System.out.println(k + "-->" + tm.get(k));
}
System.out.println("-------keySet的一般形式--------");
//keySet的一般形式
Set<Integer> keySet = tm.keySet();
for(Iterator<Integer> it = keySet.iterator(); it.hasNext();  ){
Integer key = it.next();
String value = tm.get(key);
System.out.println("年龄->" + key + "姓名->" + value );
}

System.out.println("--------增强for循环:EntrySet方法-------");
//增强for循环:EntrySet方法：
for(Entry<Integer,String> me : tm.entrySet()){
System.out.println(me.getKey() + "-->" + me.getValue());
}

System.out.println("--------Entry的一般形式-------");
//Entry的一般形式
Set<Entry<Integer,String>> entry = tm.entrySet();
for(Iterator<Entry<Integer,String>> it = entry.iterator(); it.hasNext(); ){
Entry<Integer,String> me = it.next();
Integer key = me.getKey();
String value = me.getValue();
System.out.println("年龄:" + key + "-->" + "姓名" + value);
}
}
}
</strong></span>