將對象添加到嵌套for循環內的arraylist

Question

我想循環一個JSON數組到一個數組列表Category和一個嵌套的Arraylist SubCategory。

我的問題是，我的列表不僅填充第一個子類數據，而且第二個子類數據。

例如，我想：

1st category [Apple, Kiwi] 
2nd category [Mango, Banana] 

而是我得到的，

第二類填充爲[Apple,Kiwi,Mango,Banana]。

ArrayList<Category> categoryName=new ArrayList<Category>(); 
ArrayList<ArrayList<SubCategory>> subCategoryName = new ArrayList<ArrayList<SubCategory>>(); 
ArrayList<Integer> subCategoryCount = new ArrayList<Integer>(); 

ArrayList<SubCategory> subCategoryMatches = new ArrayList<SubCategory>(); 
try { 
    // Parsing json array response 
    // loop through each json object 

    for (int i = 0; i < response.length(); i++) { 

     JSONObject allCategory = (JSONObject) response 
       .get(i); 

     int id = allCategory.getInt("mcatid"); 
     String description = allCategory.getString("description"); 

     Category categoryDetails = new Category(); 
     categoryDetails.setCatCode(id); 
     categoryDetails.setCatName(description); 
     category_name.add(categoryDetails); 

     //Log.i(TAG, String.valueOf(description)); 

     JSONArray allSubCategory = allCategory 
       .getJSONArray("Subcatergory"); 

     for (int j = 0; j < allSubCategory.length(); j++) { 

      JSONObject jsonObject = allSubCategory.getJSONObject(j); 

      String subCatId = jsonObject.getString("id"); 

      String subDescription = jsonObject.getString("description"); 

      // retrieve the values like this so on.. 

      //Log.i(TAG, String.valueOf(subDescription)); 


      SubCategory subCategoryMatch = new SubCategory(); 
      subCategoryMatch.setSubCatName(subDescription); 
      subCategoryMatch.setSubCatCode(subCatId); 
      subCategoryMatches.add(subCategoryMatch); 

     } 

     subcategory_name.add(subCategoryMatches); 
     subCatCount.add(subCategoryMatches.size()); 
    } 

Answer 1

您正在添加到相同的subCategoryMatches列表引用，因此您將獲得一個對象中的所有數據。

您需要一個新的清單，然後再添加到循環中。

ArrayList<SubCategory> subCategoryMatches; 

try { 
    // Parsing json array response 
    // loop through each json object 

    for (int i = 0; i < response.length(); i++) { 
     ... 

     // New list 
     subCategoryMatches = new ArrayList<SubCategory>(); 

     // Loop and add 
     for (int j = 0; j < allSubCategory.length(); j++) { 
      ... 
      subCategoryMatches.add(subCategoryMatch); 
     } 

     // Add new list to outer list 
     subcategory_name.add(subCategoryMatches); 
    } 
}