Question

代码很简单，我只想看看如何用全新的数据更新listview。我将值存储在数组中并将其传递给arrayadapter。单击列表视图项时，我想清除现有列表视图并添加一组新值并在列表视图中显示新项。

我可以看到数组正在使用新值进行更新，但即使在调用notifyDataSetChanged（）之后也不会显示这些值。请看一下代码，让我知道我在这里做错了什么。提前谢谢。

public class MainActivity extends Activity {
   public ListView mListView;
   String[] stringArray;
   string[] stringArray1;
   String[] stringArray2;
   String[] stringArray3;
   String[] stringArray4;
   static int track=1;
   public ArrayAdapter<String> adapter;
   public ArrayList<String[]> aList;
   static Iterator<String[]> aitr;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mListView=(ListView) findViewById(R.id.listView1);

    //stringArray= new String[4];
    stringArray1 = new String[]  {"Bright Mode1", "Normal Mode1","silly mode1", "dupe mode1","trail mode1"};
    stringArray2 = new String[] { "Bright Mode2", "Normal Mode2","silly mode2", "dupe mode2","trail mode2"};
    stringArray3 = new String[] { "Bright Mode3", "Normal Mode3","silly mode3", "dupe mode3","trail mode3"};
    stringArray4 = new String[] { "Bright Mode4", "Normal Mode4","silly mode4", "dupe mode4","trail mode4"};
    aList=new ArrayList<String[]>();
    aList.add(stringArray2);
    aList.add(stringArray3);
    aList.add(stringArray4);
    aitr=aList.iterator();

    stringArray=stringArray1;
    adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, android.R.id.text1, stringArray);
    mListView.setAdapter(adapter);
}

public void updateArray(){
    if(aitr.hasNext()){
        mListView.clearChoices();
        stringArray=aitr.next();
    }
}

@Override
protected void onStart(){
    super.onStart();
    mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
        @Override
        public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            int a = view.getId();

            Log.e("devsample", "the is is: " + a + ", " + position + ", " + id);
            updateArray();
            adapter.notifyDataSetChanged() ;
        }
    });
}

}

Answer 1

在updateArray()方法中，您为stringArray分配了新数组，但您的adapter仍然引用了旧版stringArray。在updateArray()的末尾添加以下两行，以更新adapter：

adapter.clear();
adapter.addAll(stringArray); // or if you're targeting Android < 11 call: adapter.add() in a loop

Answer 2

所以我在发表的帖子Unable to modify ArrayAdapter in ListView: UnsupportedOperationException

中将问答者的答案和st0le提供的解释混合在一起解决了这个问题。

即使在调用notifyDataSetChanged（）之后也无法更新ListView

2 个答案: