遍历循环输出map的几种方式

Posted 2020-10-27 qqyong

package 常用的遍历方法.forTest;

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

public class CircleTest {
	public static void main(String[] args) {
		Map<String,Object> map = new HashMap<String,Object>();
		map.put("accident", "意外险");
		map.put("properties", "财产险");
		map.put("biz", "商业险");
		map.put("force", "交强险");
		
		//1、迭代器
		Iterator<Map.Entry<String, Object>> iter = map.entrySet().iterator();
		//判断往下还有没有数据
		while(iter.hasNext()){
			//有的话取出下面的数据
			Entry<String, Object> entry = iter.next();
			String key = entry.getKey();
			String value = (String)entry.getValue();
			if("biz".equals(entry.getKey())){
				System.out.println("这个是商业险");
			}
			System.out.println(key + " ：" + value);
		}
		
		//2、foreach循环
		//获取key + value
		for (Object key : map.keySet()) {
			String value = (String)map.get(key);
			System.out.println(key + " : " + value);
		}
		//获取value
		for (Object value : map.values()) {
			System.out.println(value);
		}
		
		//3、当容量特别大的时候
		for (Entry<String, Object> entry : map.entrySet()) {
			/*iter :  biz=商业险
					force=交强险
					accident=意外险
					properties=财产险*/
			 System.out.println(entry.getKey() + " : " + entry.getValue());
		}
	}
}