map集合,遍歷的三種方式
阿新 • • 發佈:2019-01-27
package test; import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Map.Entry; /** * * @author jeryy yang * map遍歷的三種方式 *推薦使用第一種方式,效率比較高 */ public class map遍歷 { public static void main(String[] args) { Map<Integer, String> map = new HashMap<Integer, String>(); map.put(0, "java"); map.put(1, "php"); map.put(2, "c#"); for(Entry<Integer, String> entry : map.entrySet()) { int key = entry.getKey(); String value = entry.getValue(); System.out.println("==============方法一=============="); System.out.println("key:"+key+" value:"+value); } Iterator<Entry<Integer, String>> iterator = map.entrySet().iterator(); while(iterator.hasNext()) { Entry<Integer, String> entries = iterator.next(); int key = entries.getKey(); String value = entries.getValue(); System.out.println("==============方法二=============="); System.out.println("key:"+key+" value:"+value); } System.out.println("==============方法三=============="); for(Integer key : map.keySet()) { System.out.println("key:"+key); } for(Integer key : map.keySet()) { String value = map.get(key); System.out.println("value:"+value); } } }