如何在 Java 中使用 for 循环动态创建列表

Question

Here's what I am doing: 1. fetch array from server 2. using Asynctask, I am catching the string in my onPostExecute method 3. iterating through array list and creating the list according to the string values of the array.

But I am getting this error "Variable 'result' is already defined in this scope", i tried searching over the net. But in vain. I don't understand the problem.

Here's the code:

@Override
    protected void onPostExecute(String[] result) {
        super.onPostExecute(result);
        HashMap<String, List<String>> MoviesDetails = new HashMap<String, List<String>>();
        int count = result.length;
        for(int i=0; i<count;i++){
            List<String> result[i] = new ArrayList<String>();
         }

    }

Thanks In advance

Answer 1

You have String[] result already defined. Change

 List<String> result[i] = new ArrayList<String>();

to some another variable

Answer 2

The reason you are getting the error is this:

You have String[] result in your arguments. Then you try to define a List<String> result . So the compiler complains that you have two variables with same name.

Answer 3

Two things wrong here:

1. There is already a result variable on the onPostExecute() function. Try renaming your other result variable.

2. You cannot use the [] operator on what you are trying to achieve.

What exactly are you trying to store: A list of strings, or a list of (ArrayList)?

Answer 4

Try like this:

 @Override
  protected void onPostExecute(String[] result) {
    super.onPostExecute(result);
    int count = result.length;
    List<String> list = new ArrayList<String>();
    for (int i = 0; i < count; i++) {
        list.add(result[i]);
    }

  }

Answer 5

you are trying to create a List<String> result variable despite there being a parameter called result , so you'll need to rename it. You also need to initialise your list outside of the loop to do what you want, eg:

List<String> resultList = new ArrayList<String>();
for(int i=0; i<result.length; i++){
    resultList.add(result[i]);
}

EDIT

If you want to create multiple lists then you'll need to define a collection of type List<String> , eg:

List<List<String>> resultList = new ArrayList<List<String>>();
for(int i=0; i<result.length; i++){
    resultList.add(new ArrayList<String>());
}

Answer 6

You can directly convert your String Array to ArrayList using this

   List<String> list = new ArrayList<String>(Arrays.asList(yourStringArray))

Thanks. Hope it will help.