listView动态添加项目
我用ListView
来动态添加项目,但是有一个关于不是Smooth添加的问题。 有TextView的和按钮,在我的listActivity,Iwant按下按钮,然后TextView
的文本可以自动添加到ListView
,但我按下按钮,它DONOT工作,除非以后我进入内容,按‘OK’键,再按下按钮,TextView's
文字可以自动添加到ListView
。我不知道为什么。如果我连续按下的按钮,为3次,然后按“确定”键,内容listView动态添加项目
自动添加列表
的看法,但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控件,按钮,TextView的
- row.xml包含
TextView
回答:
notifyDataSetChanged()方法用于更新适配器。
在这里,我发布了一个工作答案的步骤。
首先main.xml中文件:
<?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>
这里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;
}
}
}
回答:
是对ListActivity
或ArrayAdapter
类的你getBtnClickListener
方法的一部分?
对我来说,当我从ListActivity
类更新,我用这个代码...
// 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);
当我从一个方法更新ArrayAdapter
类中,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;
});
回答:
我使用一个线程在后台添加更多的数据,以我的列表,然后notifydatasetchange
,它工作成功
这里是完整的代码:http://code.google.com/p/dynamic-listview/source/checkout
回答:
是!,方法notifyDataSetChanged()在一个ArrayAdapter应用你缩绒他面前,对我来说是解决方案。从Firebase阅读。
对象
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);
以上是 listView动态添加项目 的全部内容, 来源链接: utcz.com/qa/265832.html