Traverse map

Map Traversal method of collection , You can find , And key The order of insertion is different , There will be sorting effect

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

public class MapBianli {
    
	public static void main(String[] args) {
    
		Map<String, String> map = new HashMap<String, String>();
		map.put("3", "value3");
		map.put("2", "value2");
		map.put("1", "value1");
		
		

		//  The first one is ： Commonly used , Second value 
		System.out.println(" adopt Map.keySet Traverse key and value：");
		for (String key : map.keySet()) {
    
			System.out.println("key= " + key + " and value= " + map.get(key));
		}

		//  The second kind 
		System.out.println(" adopt Map.entrySet Use iterator Traverse key and value：");
		Iterator<Map.Entry<String, String>> it = map.entrySet().iterator();
		while (it.hasNext()) {
    
			Map.Entry<String, String> entry = it.next();
			System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
		}

		//  The third kind of ： recommend , Especially when the capacity is large 
		System.out.println(" adopt Map.entrySet Traverse key and value");
		for (Map.Entry<String, String> entry : map.entrySet()) {
    
			System.out.println("key= " + entry.getKey() + " and value= " + entry.getValue());
		}

		//  A fourth 
		System.out.println(" adopt Map.values() Traverse all value, But you can't traverse key");
		for (String v : map.values()) {
    
			System.out.println("value= " + v);
		}
	}
}

Ergodic result ：