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我有一個自定義視圖（其中有複選框）listview。我還在活動版面中添加了checkbox以選擇全部checkboxes。當我選中活動複選框時，我收到所有listview項目，但我無法將listview中的所有checkboxes選中。當我嘗試在for循環中使用getChildAt()時，我得到一個空指針。如何使用getChildAt獲取listview行的元素
// row layout
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal"
android:id="@+id/rootlay">
<CheckBox
android:id="@+id/cbBox"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical" >
</CheckBox>
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:orientation="vertical"
android:layout_weight="1" >
<TextView
android:id="@+id/tvDescr"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_margin="5dp"
android:text=""
android:textSize="20sp" >
</TextView>
<TextView
android:id="@+id/tvPrice"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="5dp"
android:text="" >
</TextView>
</LinearLayout>
</LinearLayout>
public class ContactsPickerActivity extends AppCompatActivity{
ArrayList<Model> arrayList = new ArrayList<>();
ListView list;
CustomAdapter adapter;
CheckBox selectall;
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_contact);
list = (ListView)findViewById(R.id.list);
Button loadbtn = (Button)findViewById(R.id.loadbtn);
loadbtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.M){
askForPermission(Manifest.permission.READ_CONTACTS,1100);
}else{
new LoadContactsAyscn().execute();
}
}
});
Button getbtn = (Button)findViewById(R.id.getbtn);
getbtn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String result = "Selected Product are :";
for (Model p : adapter.getBox()) {
if (p.box){
result += "\n" + p.price;
}
}
Toast.makeText(ContactsPickerActivity.this, result, Toast.LENGTH_LONG).show();
}
});
adapter = new CustomAdapter(ContactsPickerActivity.this, arrayList);
list.setAdapter(adapter);
selectall = (CheckBox)findViewById(R.id.selectall);
selectall.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(CompoundButton compoundButton, boolean b) {
if(b){
int count = list.getAdapter().getCount();
System.out.println("sammy_total_count "+count);
for(int i=0; i<count; i++){
adapter.getProduct(i).box=true;
LinearLayout itemlay = (LinearLayout)list.getChildAt(i);
CheckBox checkBox = (CheckBox)itemlay.findViewById(R.id.cbBox);
checkBox.setTag(i);
checkBox.setChecked(adapter.getProduct(i).box);
}
}else{
int count = list.getAdapter().getCount();
System.out.println("sammy_total_count "+count);
for(int i=0; i<count; i++){
adapter.getProduct(i).box=false;
LinearLayout itemlay = (LinearLayout)list.getChildAt(i);
CheckBox checkBox = (CheckBox)itemlay.findViewById(R.id.cbBox);
checkBox.setTag(i);
checkBox.setChecked(adapter.getProduct(i).box);
}
}
}
});
}
private void askForPermission(String permission, Integer requestCode) {
System.out.println("sammy_reached_askForPermission");
if (ContextCompat.checkSelfPermission(ContactsPickerActivity.this, permission) != PackageManager.PERMISSION_GRANTED) {
if(ActivityCompat.shouldShowRequestPermissionRationale(ContactsPickerActivity.this, permission)) {
// if (shouldShowRequestPermissionRationale(permission)) { // for fragment
ActivityCompat.requestPermissions(ContactsPickerActivity.this, new String[]{permission}, requestCode);
// requestPermissions(new String[]{permission}, requestCode); // for fragment
} else {
ActivityCompat.requestPermissions(ContactsPickerActivity.this, new String[]{permission}, requestCode);
// requestPermissions(new String[]{permission}, requestCode); // for fragment
}
} else {
new LoadContactsAyscn().execute();
}
}
@Override
public void onRequestPermissionsResult(int requestCode, String[] permissions, int[] grantResults) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
System.out.println("sammy_reached_onRequestPermissionsResult");
if(ActivityCompat.checkSelfPermission(ContactsPickerActivity.this, permissions[0]) == PackageManager.PERMISSION_GRANTED){
if(requestCode==1100){
new LoadContactsAyscn().execute();
}
Toast.makeText(ContactsPickerActivity.this, "Permission granted", Toast.LENGTH_SHORT).show();
}else{
Toast.makeText(ContactsPickerActivity.this, "Permission denied", Toast.LENGTH_SHORT).show();
}
}
class LoadContactsAyscn extends AsyncTask<Void, Void, ArrayList<Model>> {
ProgressDialog pd;
@Override
protected void onPreExecute() {
// TODO Auto-generated method stub
super.onPreExecute();
pd = ProgressDialog.show(ContactsPickerActivity.this, "Loading Contacts",
"Please Wait");
}
@Override
protected ArrayList<Model> doInBackground(Void... params) {
Cursor c = getContentResolver().query(
ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null,
null, null, null);
while (c.moveToNext()) {
String contactName = c.getString(c.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
String phNumber = c.getString(c.getColumnIndex(ContactsContract.CommonDataKinds.Phone.NUMBER));
arrayList.add(new Model(contactName,phNumber, false));
}
c.close();
return arrayList;
}
@Override
protected void onPostExecute(ArrayList<Model> contacts) {
// TODO Auto-generated method stub
super.onPostExecute(contacts);
pd.cancel();
adapter.notifyDataSetChanged();
}
}
}
你在哪裏初始化適配器？ –
什麼是列表和您初始化它的位置？活動中的 –
。 @RandykaYudhistira –