Question

当触发onItemClick时，我的代码确实更新了ListView，但只有在onItemClick方法中替换了行＆＃34;＆＃34;

                categoryAdapter.notifyDataSetChanged();

行

            lv.setAdapter(new CategoryAdapter(categories));

我应该如上所示更换线路，还是应该使用notifyDataSetChanged？因为文档说它也应该更新视图。

此外，当我这样做时，应用程序会运行，但是按下后退按钮会关闭应用程序，而不是返回到我希望看到的最后一个屏幕。

public class MainActivity extends ActionBarActivity {
ListView lv;
String[] categories = null;
private static String[] failCategories = {"a","b","c};
private static String[] category_a= { "a1","a2"};

CategoryAdapter categoryAdapter = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_categories);

    lv = (ListView) findViewById(R.id.lvCategories);
    categories = failCategories;        //initial set
    categoryAdapter = new CategoryAdapter(categories);
    lv.setAdapter(categoryAdapter);
    lv.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            if (position == 0){
                categories = category_a;
                categoryAdapter.notifyDataSetChanged();
            }

        }
    });
}

private class CategoryAdapter extends ArrayAdapter<String>{
    CategoryAdapter(String[] objects) {
        super(getBaseContext(), R.layout.activity_categories,R.id.tvCategory, objects);
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        convertView = super.getView(position, convertView, parent); 
        return convertView;                 
    }
}

}

Answer 1

如果您只想更新尊重的项目，请在代码中尝试此部分代码，确保category_a具有相同的项目

版本1

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {

                categoryAdapter.insert(position,category_a[position]);  
                categoryAdapter.notifyDataSetChanged();


        }

版本2 如果你想用category_a中的所有项目更新整个列表视图，那么

public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    categoryAdapter.clear();
                    categoryAdapter.addAll(category_a);                
                    categoryAdapter.notifyDataSetChanged();


}

在onItemClick上更新ListView数据

1 个答案: