Map的显示值的方法

传统方法:

第一种:

@Test
	public void test1() {
		Map m =new HashMap();  //显示的是3,2,1
		//Map m =new LinkedHashMap();  //显示的是1,2,3
		m.put("1","aaaa");
		m.put("2","baaa");
		m.put("3","caaa");
		
		Set set = m.keySet();
		Iterator it = set.iterator();
		while(it.hasNext()) {
			String key = (String) it.next();
			String value = (String) m.get(key);
			System.out.println(key+"----"+value);
		}
	}


显示:

3----caaa
2----baaa
1----aaaa

 

第二种:

@Test
	public void test2() {
		//Map m =new HashMap();  //显示的是3,2,1
		Map m =new LinkedHashMap();  //显示的是1,2,3
		m.put("1","aaaa");
		m.put("2","baaa");
		m.put("3","caaa");
		
		Set set = m.entrySet();
		Iterator it = set.iterator();
		while(it.hasNext()) {
			Map.Entry entry = (Entry) it.next();
			String key = (String) entry.getKey();
			String value = (String) entry.getValue();
			System.out.println(key+"----"+value);
		}
	}


显示:

1----aaaa
2----baaa
3----caaa


for加强版本:

第一种:

@Test
	public void test3() {
		//Map m =new HashMap();  //显示的是3,2,1
		Map m =new LinkedHashMap();  //显示的是1,2,3
		m.put("1","aaaa");
		m.put("2","baaa");
		m.put("3","caaa");
		
		for(Object o: m.keySet()) {
			String key = (String) o;
			String value = (String) m.get(key);
			System.out.println(key+"----"+value);
		}
	}

第二种:

	@Test
	public void test4() {
		//Map m =new HashMap();  //显示的是3,2,1
		Map m =new LinkedHashMap();  //显示的是1,2,3
		m.put("1","aaaa");
		m.put("2","baaa");
		m.put("3","caaa");

		for(Object o:m.entrySet()) {
			Map.Entry entry = (Entry) o;
			String key = (String) entry.getKey();
			String value = (String) entry.getValue();
			System.out.println(key+"----"+value);
		}
	}


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