Question

我有一个ListActivity类。它有一个按钮，根据其中一个属性对项目进行排序。但事实上，该项目正按其名称进行排序，但点击其原始位置的项目后即被执行。以下是代码段：

public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.playlist);

        mButton = (ToggleButton) findViewById(R.id.mButton);

        ArrayList<myObject> ListData = new ArrayList<myObject>();

        back = (ImageButton) findViewById(R.id.backButton);
        label = (TextView) findViewById(R.id.likethis);
        label.setText("List");
        inputSearch = (EditText) findViewById(R.id.inputSearch);

        //Manager -- class that reads from the sdcard
        Manager plm = new Manager();

        // get all files from sdcard
        //getList() function of Manager class
        //List declared outside oncreate()
        this.List = plm.getList(); 

        final ArrayList<myObject> backUp = new ArrayList<myObject>(songsList);

        if(sortCalled) {
            mButton.setBackgroundDrawable(getResources().getDrawable(R.drawable.m_checked));
            mButton.setChecked(true);
            Collections.sort(List);

            notifyDataChanged(List);
        }
        else {
            mButton.setBackground(getResources().getDrawable(R.drawable.m_unchecked));
            mButton.setChecked(false);
            notifyDataChanged(backUp);
        }

        back.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View arg0) {
                // TODO Auto-generated method stub
                finish();
            }

        });

        inputSearch.addTextChangedListener(new TextWatcher(){

            @Override
            public void afterTextChanged(Editable arg0) {
                // TODO Auto-generated method stub
                adapter.notifyDataSetChanged();
            }

            @Override
            public void beforeTextChanged(CharSequence s, int start, int count,
                    int after) {
                // TODO Auto-generated method stub

            }

            @Override 
            public void onTextChanged(CharSequence s, int start, int before,
                    int count) {
                // TODO Auto-generated method stub
                //ArrayList <Song> temp;
                ((SimpleAdapter) PlayListActivity.this.adapter).getFilter().filter(s, new Filter.FilterListener() {

                    public void onFilterComplete(int count) {
                        // TODO Auto-generated method stub
                        adapter.notifyDataSetChanged();
                    }
                });
                adapter.notifyDataSetChanged();


            }

        });

        mButton.setOnClickListener(new OnClickListener(){

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                if(mButton.isChecked()){
                    mButton.setBackgroundDrawable(getResources().getDrawable(R.drawable.m_checked));
                    Collections.sort(List);
                    sortCalled = true;
                    notifyDataChanged(List);
                }
                else{
                    sortCalled = false;
                    mButton.setBackgroundDrawable(getResources().getDrawable(R.drawable.m_unchecked));
                    notifyDataChanged(backUp);
                }
            }

        });
    }

    public void settingListAdapter(SimpleAdapter adapter){
        setListAdapter(adapter);
        ListView lv = getListView();
        // listening to single listitem click
        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // getting listitem index
                int Index = position;

                // Starting new intent
                Intent in = new Intent(getApplicationContext(),
                        MainActivity.class);
                // Sending Index to MainActivity
                in.putExtra("Index", Index);
                setResult(100, in);
                // Closing ListView
                finish();
            }
        });
    }

    public void notifyDataChanged(ArrayList<Song> songsList) {
        // TODO Auto-generated method stub
        setListAdapter(null);
        sortCalled = true;
        ArrayList<myObject> songsListData = new ArrayList<myObject>();

        for (int i = 0; i < songsList.size(); i++) {
            // creating new HashMap
            myObject ob = sList.get(i);

            // adding HashList to ArrayList
            ListData.add(ob);
        }

        ArrayList<HashMap<String, String>> array = new ArrayList<HashMap<String,String>>();
       // int j = 0;
        for(myObject i : ListData){
            HashMap<String, String> feed = new HashMap<String, String>();
            feed.put("Title", i.getTitle());
            array.add(feed);

        }
        BaseAdapter adapter1;
       // int i = 0;
        // Adding menuItems to ListView
         adapter1 = new SimpleAdapter(this, array,
                R.layout.list_item, new String[]{"Title" }, new int[] {
                        R.id.Title });

        setListAdapter(adapter1);
        adapter1.notifyDataSetChanged();

        ListView lv = getListView();
        // listening to single listitem click

        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                // getting listitem index
                int Index = position;

                // Starting new intent
                Intent in = new Intent(getApplicationContext(),
                        MainActivity.class);
                // Sending songIndex to MainActivity
                in.putExtra("Index", Index);
                setResult(100, in);
                // Closing ListView
                finish();
            }
        });

Answer 1

我认为你应该试试这个。当你对listview的数据进行排序时，我的工作非常完美

 adapter.notifyDataSetChanged();

Answer 2

每次更改适配器时，都应该在UIThread中调用notifyDataSetChanged（）

请检查this video以更好地了解listView

修改
对于ArrayAdapter，只有在适配器上使用add, insert, remove, and clear函数时，notifyDataSetChanged才有效。

构造ArrayAdapter时，它保存传入的List的引用。如果要传入属于Activity成员的List，并稍后更改该Activity成员，则ArrayAdapter仍然保持引用原始列表。适配器不知道您更改了活动中的列表。

您的选择是：

使用ArrayAdapter的功能修改基础列表(add, insert, remove, clear, etc.) 使用新的List数据重新创建ArrayAdapter。（使用大量资源和垃圾收集。）创建自己的派生自BaseAdapter和ListAdapter的类，允许更改基础List数据结构。每次更新列表时使用notifyDataSetChanged。要在UI-Thread上调用它，请使用Activity的runOnUiThread方法。然后notifyDataSetChanged将起作用。

Answer 3

您可以尝试使用Adapter.notifyDataSetChanged（）函数。它可能会奏效。

如果您使用的是SimpleCursorAdapter，则在连接到适配器的光标上调用requery（）将自动刷新适配器和附加视图。

如果它的BaseAdapter内容发生了变化，你可以调用BaseAdapter.notifyDataSetChanged（）来告诉ListView自我更新。

换句话说，你只需进行以下微小改动：

public void setValue(Object newValue) {
     this.value = newValue;
     notifyDataSetChanged();
}

实际上，由于您正在更改现有项目的状态（而不是添加新项目等），因此notifyDataSetInvalidated（）将是更好的选择。

如何刷新活动中的ListView

3 个答案: