foreach循环详解
在Java1.5+中,foreach循环非常实用.
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
1 public class Demo <T> implements Iterable<T>, Iterator<T> { 2 T[] array; 3 int length; 4 int index; 5 6 Demo(T[] param){ 7 array = param; 8 length = array.length; 9 } 10 11 public static void main(String[] args) { 12 Demo<String> demo = new Demo<String>(new String[]{"aaa","bbb"}); 13 for(String str : demo){ 14 System.out.println(str); 15 } 16 } 17 18 public Iterator<T> iterator(){ 19 return this; 20 } 21 22 public void remove(){ 23 } 24 25 public boolean hasNext(){ 26 index = (index+1)%(length+1); 27 if(index==0)return false; 28 return true; 29 } 30 31 public T next(){ 32 return array[index-1]; 33 } 34 } 35 36 /*output: 37 aaa 38 bbb 39 */
上述代码等价于以下形式
1 public static void main() { 2 Demo<String> demo = new Demo<String>(new String[]{"aaa","bbb"}); 3 Iterator<String> iterator = demo.iterator(); 4 whlie(iterator.hasNext()){ 5 String tmp = iterator.next(); 6 System.out.println(tmp); 7 } 8 }