java中Map迴圈的幾種方式
阿新 • • 發佈：2019-02-08
package com.xhx.collection; import org.junit.Test; import java.util.HashMap; import java.util.Iterator; import java.util.Map; /** * xuhaixing * 2018/7/15 19:59 **/ public class TestHashMapApp { /** * 迴圈的幾種方式 */ @Test public void testHashMap1(){ Map<String,String> map = new HashMap<String, String>(); map.put("a","aaa"); map.put("b","bbb"); map.put("c","ccc"); map.put("d","ddd"); //通過key Set<T> key = map.keySet() for(String key:map.keySet()){ System.out.println("key="+key+" value="+map.get(key)); } //key和value都迴圈 for(Map.Entry<String,String> entry : map.entrySet()){ System.out.println("key="+entry.getKey()+" value="+entry.getValue()); } //通過迭代器 Iterator<Map.Entry<String, String>> iterator = map.entrySet().iterator(); while (iterator.hasNext()){ Map.Entry<String, String> entry = iterator.next(); System.out.println("key="+entry.getKey()+" value="+entry.getValue()); } //只迴圈value for(String value : map.values()){ System.out.println("value="+value); } } }