在java中數組的呼叫預設是是傳址呼叫:主體方法中傳遞一個數組給某個方法,在該方法內修改了數組的某個值;回到主方法中會發現數組已經改變了;
測試程式碼:
public class ArrayTest { public static void main(String[] args){ Map[] maparray=new Map[3]; for (int i = 0; i < maparray.length; i++) { Map<String,String> map=new HashMap<String,String>(); map.put("a", i+"_ajkcz"); map.put("c", "werq_"+i); maparray[i]=map; } System.out.println("++++++++++++++++++++++++"); for (int i = 0; i < maparray.length; i++) { Map<String,String> map=maparray[i]; Iterator it=map.keySet().iterator(); while(it.hasNext()){ String key=(String) it.next(); System.out.println(key+"\t"+map.get(key) ); } } System.out.println("++++++++++++++++++++++++"); new ArrayCharge().printAndChangeArray(maparray); System.out.println("++++++++++++++++++++++++"); for (int i = 0; i < maparray.length; i++) { Map<String,String> map=maparray[i]; Iterator it=map.keySet().iterator(); while(it.hasNext()){ String key=(String) it.next(); System.out.println(key+"\t"+map.get(key) ); } } } } class ArrayCharge { public void printAndChangeArray(Map[] maparray){ for (int i = 0; i < maparray.length; i++) { Map<String,String> map=maparray[i]; map.put("a",i+"________"); } for (int i = 0; i < maparray.length; i++) { Map<String,String> map=maparray[i]; Iterator it=map.keySet().iterator(); while(it.hasNext()){ String key=(String) it.next(); System.out.println(key+"\t"+map.get(key) ); } } } } 控制台输出结果: ++++++++++++++++++++++++ cwerq_0 a0_ajkcz cwerq_1 a1_ajkcz cwerq_2 a2_ajkcz ++++++++++++++++++++++++ cwerq_0 a0________ cwerq_1 a1________ cwerq_2 a2________ ++++++++++++++++++++++++ cwerq_0 a0________ cwerq_1 a1________ cwerq_2 a2________
而在php中,數組的調用預設是傳值調用,在字方法中修改了數組,在父方法中無法察覺
測試程式碼:
控制台輸出:<?php $arraytest=array(); for($i=0;$i<3;$i++){ $child=array(); $child['keystr']='key'.$i; $child['valuestr']='value'.$i; $arraytest[]=$child; } print_r($arraytest); print_r("+++++++++++++++++++++++++"); for($i=0;$i<count($arraytest);$i++){ $child=$arraytest[$i]; $child['valuestr']="_________".$i; } print_r($arraytest); print_r("+++++++++++++++++++++++++"); ?>
Array ( [0] => Array ( [keystr] => key0 [valuestr] => value0 ) [1] => Array ( [keystr] => key1 [valuestr] => value1 ) [2] => Array ( [keystr] => key2 [valuestr] => value2 ) ) +++++++++++++++++++++++++ Array ( [0] => Array ( [keystr] => key0 [valuestr] => value0 ) [1] => Array ( [keystr] => key1 [valuestr] => value1 ) [2] => Array ( [keystr] => key2 [valuestr] => value2 ) ) +++++++++++++++++++++++++
控制台輸出:
<?php $arraytest=array(); for($i=0;$i<3;$i++){ $child=array(); $child['keystr']='key'.$i; $child['valuestr']='value'.$i; $arraytest[]=$child; } print_r($arraytest); print_r("+++++++++++++++++++++++++"); for($i=0;$i<count($arraytest);$i++){ $child=&$arraytest[$i]; //注意这里加了一个指针符号,代表是传址调用 $child['valuestr']="_________".$i; } print_r($arraytest); print_r("+++++++++++++++++++++++++"); ?>