Question

我使用ListView动态添加项目，但是有一个问题是没有平滑添加。我的listActivity中有textView和按钮，Iwant to Press按钮，然后TextView的文本可以自动添加到ListView，但我按下按钮，它不工作，除非输入内容后按“确定“按键，然后按下按钮，TextView's文字可以自动添加到ListView。我不知道为什么。如果我连续按下按钮，为3次，则按“确定”键，内容

自动添加列表

查看3次。

 public class DynamicListItems extends ListActivity {
   private static final String   ITEM_KEY   = "key";
   ArrayList<HashMap<String, String>>   list= new ArrayList<HashMap<String, String>>();
private SimpleAdapter   adapter;
private EditText    newValue;@Override
public void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.dynamic_list);
    newValue = (EditText) findViewById(R.id.new_value_field);

    setListAdapter(new SimpleAdapter(this, list, R.layout.row, new String[] { ITEM_KEY }, new int[] { R.id.list_value }));
    ((ImageButton) findViewById(R.id.button)).setOnClickListener(getBtnClickListener());
}

private OnClickListener getBtnClickListener() {
    return new OnClickListener() {
        public void onClick(View view) {
            try {

                HashMap<String, String> item = new HashMap<String, String>();
                item.put(ITEM_KEY, newValue.getText().toString());
                list.add(item);

                adapter.notifyDataSetChanged();
            } catch (NullPointerException e) {
                Log.i("[Dynamic Items]", "Tried to add null value");
            }
        }
    };
   }}

如何动态删除项目？

dynamic_list.xml只包含listView，button，textView
row.xml包含TextView

Answer 1

notifyDataSetChanged（）方法用于更新适配器。

我在这里逐步发布工作答案。

main.xml 文件的第一个：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true" 
        android:id="@+id/input">

        <EditText
            android:id="@+id/editText_input"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:ems="10" >

            <requestFocus />
        </EditText>

        <Button
            android:id="@+id/button_add"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="0"
            android:text="Add" />
    </LinearLayout>


    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="match_parent"
        android:layout_above="@+id/input"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:orientation="vertical" >

        <ListView
            android:id="@+id/listView_items"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" >
        </ListView>

    </LinearLayout>

</RelativeLayout>

此处 MainActivity.java ：

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ListView;

public class MainActivity extends Activity {
    private EditText etInput;
    private Button btnAdd;
    private ListView lvItem;
    private ArrayList<String> itemArrey;
    private ArrayAdapter<String> itemAdapter;

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dyanamic_list);
        setUpView();

    }

    private void setUpView() {
        etInput = (EditText)this.findViewById(R.id.editText_input);
        btnAdd = (Button)this.findViewById(R.id.button_add);
        lvItem = (ListView)this.findViewById(R.id.listView_items);

        itemArrey = new ArrayList<String>();
        itemArrey.clear();

        itemAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1,itemArrey);
        lvItem.setAdapter(itemAdapter);

        btnAdd.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                addItemList();
            }
        });

        etInput.setOnKeyListener(new View.OnKeyListener() {
            public boolean onKey(View v, int keyCode, KeyEvent event) {
                if (keyCode == KeyEvent.KEYCODE_ENTER) {
                    addItemList();
                }
                return true;
            }
        });
    }

    protected void addItemList() {
        if (isInputValid(etInput)) {
            itemArrey.add(0,etInput.getText().toString());
            etInput.setText("");
            itemAdapter.notifyDataSetChanged();
        }   
    }

    protected boolean isInputValid(EditText etInput2) {
        if (etInput2.getText().toString().trim().length()<1) {
            etInput2.setError("Please Enter Item");
            return false;
        } else {
            return true;
        }
    }
}

Answer 2

您的getBtnClickListener方法是ListActivity或ArrayAdapter类的一部分吗？

对我来说，当我从ListActivity课程更新时，我会使用此代码...

// code to add a Contact to my database
// code to add a Contact to the list that
//   that is used by the ListView
setListAdapter(adapter);
getListView().setTextFilterEnabled(true);

当我从ArrayAdapter类中的方法更新时，我使用此代码...

 // from a LongPress on a ListView item
 convertView.setOnLongClickListener(new OnLongClickListener(){
     @Override
     public boolean onLongClick(View view) {
         view.performHapticFeedback(0, View.HAPTIC_FEEDBACK_ENABLED);
         // code to remove a Contact name from my database
         // code to remove that Contact name from my list
         //    that is used by the ListView
         ContactsAdapter.this.notifyDataSetChanged();
         return true;
     });

Answer 3

我使用线程在后台添加更多数据到我的列表，然后notifydatasetchange，它成功运行

以下是完整代码：http://code.google.com/p/dynamic-listview/source/checkout

Answer 4

是!!，在你填充他之前在ArrayAdapter中应用的方法notifyDataSetChanged（）是我的解决方案。从Firebase阅读。

物件

    private DatabaseReference myRef;
    ArrayList<String> lista;
    ArrayAdapter<String> adapter;

的OnCreate

    FirebaseDatabase database = FirebaseDatabase.getInstance();
    myRef = database.getReference("chat");

    //GETTIN MY DATA TO SHOW IN CHAT
    lista = new ArrayList<String>();

的onResume

    myRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            for (DataSnapshot postSnappy : dataSnapshot.getChildren()){
                for (DataSnapshot rePostSnappy : postSnappy.getChildren()){
                    // Defined Array values to show in ListView
                    lista.add(new String(rePostSnappy.getValue().toString()));
                    adapter.notifyDataSetChanged();//Notyfing adapter that will goes to change
                }
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

    adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_list_item_1, lista);

    ListView listVista = (ListView) findViewById(R.id.list);
    listVista.setAdapter(adapter);

listView动态添加项目

4 个答案: