java中HashMap遍历方法【集合】

 import java.util.HashMap; import java.util.Iterator; import java.util.Set; import java.util.Map.Entry;public class Test4 { public static void main(String[] args) { HashMap<Integer, String> map = new HashMap<Integer, String>(); map.put(1, "xcp"); map.put(2, "ok"); map.put(3, "lxm"); /* * 第一种 */ Set<Entry<Integer, String>> set = map.entrySet(); Iterator<Entry<Integer, String>> itor = set.iterator(); while(itor.hasNext()) { Entry<Integer, String> entry = itor.next(); System.out.println(entry.getKey()+" "+entry.getValue()); } /* * 第二种 */ for(Entry<Integer, String> entry : map.entrySet()) System.out.println(entry.getKey()+" "+entry.getValue()); } }

 

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在java中使用HashMap是主要有两种遍历方法，代码如下：第一种：HashMap hashmap = new HashMap();Iterator iterator = hashmap.keySet().iterator();while (iterator.hasNext()) { Object value = hashmap.get(iterator.next());}第二种：HashMap hashmap = new HashMap();Iterator iterator = hashmap.keySet().iterator(); while (iterator .hasNext()) { Entry entry = (Entry) iterator.next(); Object value= entry.getValue(); Object key =entry.getKey(); }据说使用第二种方法要比第一种方法效率快

 

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HashMap按照插入顺序排序：

HashMap<String, String> hash = new LinkedHashMap<String, String>();

hash.put(obj[0].toString(), obj[1].toString());