Question

我在Android中遇到了GridView的问题。我看过类似的帖子，但这不一样。问题是我为我的GridView设置了一个适配器然后我想做一些计算并决定选择GridView的一个元素，我想将TextView的背景设置为绿色。这是代码示例：

  GridView gv = findViewById(R.id.gridView);
  final String[] answerStrings = new String[] {
                TEXT_IN_DRAG_AND_DROP_BOXES,    TEXT_IN_DRAG_AND_DROP_BOXES,
                TEXT_IN_DRAG_AND_DROP_BOXES };
  ArrayAdapter<String> answersViewAdapter = new ArrayAdapter<String>(
                this, android.R.layout.simple_list_item_1, answerStrings);

        gv.setAdapter(answersViewAdapter);
        int a = // some process which tells me which child should I change the background of
        gv.getChildAt(a-1).setBackgroundColor(
                        DRAG_AND_DROP_COLOR_BACKGROUND);

我收到了NPE，我知道这是因为视图还不可见。但我不知道该如何解决这个问题。

Answer 1

创建自定义适配器并在getView中执行此计算以确定textview以更改背景颜色。

试试这个：

ArrayAdapter<String> choicesForViewAdapter = new ArrayAdapter<String>(
                this, R.layout.simple_list_item_1, choices) {
            @Override
            public View getView(int position, View convertView, ViewGroup parent) {

                View v = super.getView(position, convertView, parent);
                int temp = userAnswers[questionNumber - 1];
                while (temp != 0) {
                    int a = temp % 10;
                    if (position == a - 1) {
                        v.setBackgroundColor(DRAG_AND_DROP_COLOR_BACKGROUND);
                        break;
                    }
                    temp = temp / 10;
                }
                return v;
            };
        };

设置GridView元素的背景颜色

1 个答案: