Java遍历Map键、值和获取Map大小的方法示例

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
public class HashMapTest2
{
 public static void main(String[] args)
 {
 HashMap map = new HashMap();
 
 map.put("a","aaaa");
 map.put("b","bbbb");
 map.put("c","cccc");
 map.put("d","dddd");
 
 Set set = map.keySet();
 
 for(Iterator iter = set.iterator(); iter.hasNext();)
 {
  String key = (String)iter.next();
  String value = (String)map.get(key);
  System.out.println(key+"===="+value);
 }
 }
}

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class HashMapTest4
{
 public static void main(String[] args)
 {
 HashMap map = new HashMap();
 
 map.put("a","aa");
 map.put("b","bb");
 map.put("c","cc");
 map.put("d","dd");
 
 Set set = map.entrySet();
 
 for(Iterator iter = set.iterator(); iter.hasNext();)
 {
  Map.Entry entry = (Map.Entry)iter.next();
  
  String key = (String)entry.getKey();
  String value = (String)entry.getValue();
  System.out.println(key +" :" + value);
 }
 }
}

public static void main(String[] args) {

  Map map = new HashMap();

  map.put("apple", "新鲜的苹果");   //向列表中添加数据

  map.put("computer", "配置优良的计算机");  //向列表中添加数据

  map.put("book", "堆积成山的图书");   //向列表中添加数据

  System.out.println("Map集合大小为："+map.size());

}