Question

lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> adapterView, View view, int position, long   l) {

            if (selectedCourses.contains(courseNames.get(position))){
                selectedCourses.remove(selectedCourses.lastIndexOf(courseNames.get(position)));
                Toast.makeText(getApplicationContext(),
                      courseNames.get(position) + " removed", Toast.LENGTH_LONG)
                      .show();

                row = view;
                row.setBackgroundResource(R.drawable.charback);

                System.out.println(selectedCourses);
            }

            else{
                selectedCourses.add(courseNames.get(position));
                Toast.makeText(getApplicationContext(),
                        courseNames.get(position) +" added", Toast.LENGTH_LONG)
                          .show();

                row = view;
                row.setBackgroundResource(R.drawable.white);

                myarrayAdapter.notifyDataSetChanged();
                System.out.println(selectedCourses);

            }

所选项目变为白色，但是大约12个项目后期另一个随机项目变成白色就像进入视野一样？有人可以帮帮我吗？

Answer 1

您的适配器中的getView方法不会回收/重复使用提供的convertView。

如果convertView不为null，则表示它是一个正在重用的视图。这意味着您应该将后台资源显式设置为默认值，除非选中该项。您看到重复使用白色背景的原因是因为您不将背景重置为默认值。

类似的东西：

if (convertView != null) {
   if (selectedCourses.contains(courseNames.get(position))){
       convertView.setBackgroundResource(R.drawable.white);
   } else {
       convertView.setBackgroundResource(R.drawable.charback);
   }
}

Answer 2

试试这个：

lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
    @Override
    public void onItemClick(AdapterView<?> adapterView, View view, int position, long   l) {

        if (selectedCourses.contains(courseNames.get(position))){
            selectedCourses.remove(selectedCourses.lastIndexOf(courseNames.get(position)));
            Toast.makeText(getApplicationContext(),
                  courseNames.get(position) + " removed", Toast.LENGTH_LONG)
                  .show();

            row = view;
            row.setBackgroundResource(R.drawable.charback);

            System.out.println(selectedCourses);
        }

        else{
            selectedCourses.add(courseNames.get(position));
            Toast.makeText(getApplicationContext(),
                    courseNames.get(position) +" added", Toast.LENGTH_LONG)
                      .show();

            row = view;
            row.setBackgroundResource(R.drawable.white);

            System.out.println(selectedCourses);

        }

我删除了myarrayAdapter.notifyDataSetChanged（）;线...

Answer 3

您可以使用Holder类：

在你的适配器类中创建另一个包含组件的静态类：参见下面的代码

static class MyHolder {

        TextView mTextView;
        RelativeLayout lv;
        ImageView imgInvite;
        RelativeLayout rel_bckground;
    }

之后在你的getView方法中使用它：

   @Override
   public View getView(int position, View convertView, ViewGroup parent) {

           View row = convertView;
            holder = null;

          if (row == null) {

         // initialize your components
         holder = new MyHolder();
         holder.mImageView = (ImageView) row.findViewById(R.id.someID);

        }else{

         holder = (MyHolder) row.getTag();
             }
    }

ListView项目更改颜色问题。多个项目会更改视图

3 个答案: