Question

我有一个接口，哪些方法正在其他类中实现。在该方法中，我需要 forLoop 来检查特定列表中是否已经存在该项目，但是 ForLoop 会连续调用。
这是我的代码：

@Override
public void saveResultList(MyOrderResultPOJO myOrderResultPOJO) {

    myOrderResultList.add(myOrderResultPOJO);


    checkItemId(myOrderResultPOJO);

    //myOrderResultHashMap.put(inventoryClassificationId, myOrderResultList);
    setMyOrderResultListNew(myOrderResultList);
}

private boolean checkItemId(MyOrderResultPOJO myOrderResultPOJO){
    boolean v=false;

    for (int i=0;i<myOrderResultList.size();i++) {

        if (myOrderResultList.get(i).getItemId().equals(myOrderResultPOJO.getItemId())) {
            myOrderResultList.add(i,myOrderResultPOJO);
            Log.d("myOrderResultList","entering");
            v=true;
        }
    }

    return v;

}

接口：

public interface MyOrderSubList {
    void addMtPcsSpinner(Context ctx, Spinner spinner);

    void showMessages(String message);

    void hideKeyBoards();

    void saveResultList(MyOrderResultPOJO myOrderResultPOJO);
}

Answer 1

You should just return true if you find a match. You definitely don't want to add the existing element to the List again (myOrderResultList.add(i,myOrderResultPOJO); is the cause of the infinite loop).

private boolean checkItemId(MyOrderResultPOJO myOrderResultPOJO)
{
    for (int i=0;i<myOrderResultList.size();i++) {
        if (myOrderResultList.get(i).getItemId().equals(myOrderResultPOJO.getItemId())) {
            Log.d("myOrderResultList","entering");
            return true;
        }
    }

    return false;    
}

That said, the logic of the caller method (saveResultList) is strange. First you add the element to the List, and later you call checkItemId(myOrderResultPOJO), which checks if it exists in the List (and you ignore the value returned by that method). It should probably be the other way around:

public void saveResultList(MyOrderResultPOJO myOrderResultPOJO) 
{
    if (!checkItemId(myOrderResultPOJO)) {
        myOrderResultList.add(myOrderResultPOJO);
    }

    setMyOrderResultListNew(myOrderResultList);
}

Answer 2

You're ending up adding to the size of the list which is what thc condition of your for loop is i<myOrderResultList.size() :

myOrderResultList.add(i,myOrderResultPOJO); // not required

So you can update it to

for (int i = 0; i < myOrderResultList.size(); i++) {
    if (myOrderResultList.get(i).getItemId().equals(myOrderResultPOJO.getItemId())) {
        Log.d("myOrderResultList", "entering");
        v = true;
    }
}

ForLoop连续循环内部重写方法Android

2 个答案: