问题
I am using Listview and set the multiple item and each item have Like, share and comment option.
Actually I have fetch the Item Id and also setText of TextView, Its Successfully. But Not able to get Item Id on Like Button Click event for particular item.
How to fetch Item Id for every items in Listview on Button Click Event?
Demo for MyAdapter Class:
public class Adapter1 extends BaseAdapter implements OnClickListener {
public ArrayList<HashMap<String, String>> arr = null;
Context context = null;
LayoutInflater layoutInflater = null;
HashMap<String, String> getData = new HashMap<String, String>();
String urlLike = null;
TextView strId = null;
public NewsFeedAdapter(Context context,
ArrayList<HashMap<String, String>> arr) {
this.context = context;
this.arr= arr;
layoutInflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
return arr.size();
}
@Override
public Object getItem(int position) {
return arr.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if (convertView == null) {
convertView = layoutInflater.inflate(
R.layout.my_list_item, null);
/** initialize ViewHolder */
viewHolder = new ViewHolder();
/** Initialize Widgets */
/** Imageview */
viewHolder.imgLike = (ImageView) convertView
.findViewById(R.id.imgLike);
viewHolder.imgLike.setOnClickListener(this);
viewHolder.imgComments = (ImageView) convertView
.findViewById(R.id.imgComments);
viewHolder.imgComments.setOnClickListener(this);
viewHolder.imgShare = (ImageView) convertView
.findViewById(R.id.imgShare);
viewHolder.imgShare.setOnClickListener(this);
/** TextView */
viewHolder.txtId = (TextView) convertView
.findViewById(R.id.txtId);
viewHolder.txtDescription = (TextView) convertView
.findViewById(R.id.txtDescription);
getData = arr.get(position);
viewHolder.txtId.setText(getData
.get(Fragment1.TAG_ID));
viewHolder.txtDescription.setText(getData
.get(Fragment1.TAG_MESSAGE));
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
convertView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
return convertView;
}
/** ViewHolder Class */
public class ViewHolder {
ImageView imgLike = null, imgComments = null,
imgShare = null;
TextView txtId = null,txtDescription = null;
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.imgLike:
strId = ((TextView) view
.findViewById(R.id.txtId));
System.out.println("On Click====="
+ strId.getText().toString());
urlLike = "http://www.example.com?id="
+ strId.getText().toString() + "&user_id="
+ myDetail.getUserId();
new sendLikeData().execute();
break;
case R.id.imgComments:
break;
case R.id.imgShare:
break;
default:
break;
}
}
public class sendLikeData extends AsyncTask<Void, Void, Void> {
protected void onPreExecute() {
super.onPreExecute();
}
@Override
protected Void doInBackground(Void... arg0) {
ServiceHandler sh = new ServiceHandler();
String jsonStr = sh.makeServiceCall(urlLike, ServiceHandler.GET);
Log.d("Response : Like", ">" + jsonStr);
return null;
}
protected void onPostExecute(Void result) {
super.onPostExecute(result);
};
}
}
OutPut is, NullPointer Exception in System.out.println("On Click====="
+ strId.getText().toString());.
xml file is,
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/masterLayout"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_margin="@dimen/five_dp" >
<TextView
android:id="@+id/txtDescription"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_marginLeft="@dimen/ten_dp"
android:layout_marginRight="@dimen/ten_dp"
android:layout_marginTop="@dimen/ten_dp" />
<ImageView
android:id="@+id/imgImage"
android:layout_width="fill_parent"
android:layout_height="150dp"
android:layout_below="@+id/txtDescription"
android:layout_centerHorizontal="true"
android:layout_marginBottom="@dimen/ten_dp"
android:layout_marginLeft="@dimen/ten_dp"
android:layout_marginRight="@dimen/ten_dp"
android:layout_marginTop="@dimen/ten_dp"
android:background="@null"
android:contentDescription="@string/content_description"
android:src="@drawable/ic_launcher" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="@+id/imgImage"
android:background="@drawable/strip"
android:baselineAligned="false"
android:gravity="center_vertical"
android:orientation="horizontal" >
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1" >
<ImageView
android:id="@+id/imgLike"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerInParent="true"
android:contentDescription="@string/content_description"
android:src="@drawable/like" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignTop="@+id/imgLike"
android:layout_toRightOf="@+id/imgLike"
android:background="@drawable/getbg"
android:gravity="center"
android:padding="@dimen/two_dp"
android:textColor="@color/white"
android:textSize="@dimen/ten_sp" />
</RelativeLayout>
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1" >
<ImageView
android:id="@+id/imgComments"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerInParent="true"
android:contentDescription="@string/content_description"
android:src="@drawable/comments" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_toRightOf="@+id/imgComments"
android:background="@drawable/getbg"
android:gravity="center"
android:padding="@dimen/two_dp"
android:text="+1"
android:textColor="@android:color/white"
android:textSize="@dimen/ten_sp" />
</RelativeLayout>
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1" >
<ImageView
android:id="@+id/imgShare"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerInParent="true"
android:contentDescription="@string/content_description"
android:src="@drawable/share" />
</RelativeLayout>
</LinearLayout>
<TextView
android:id="@+id/txtId"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:layout_margin="@dimen/ten_dp"
android:text="id"
android:textSize="20dp" />
</RelativeLayout>
And Logcat is,
11-24 18:54:20.354: E/AndroidRuntime(7120): java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to android.widget.TextView
11-24 18:54:20.354: E/AndroidRuntime(7120): Adapter.onClick(Fragment.java:342)
11-24 18:54:20.354: E/AndroidRuntime(7120): at android.view.View.performClick(View.java:4562)
11-24 18:54:20.354: E/AndroidRuntime(7120): at android.view.View$PerformClick.run(View.java:18918)
11-24 18:54:20.354: E/AndroidRuntime(7120): at android.os.Handler.handleCallback(Handler.java:808)
11-24 18:54:20.354: E/AndroidRuntime(7120): at android.os.Handler.dispatchMessage(Handler.java:103)
11-24 18:54:20.354: E/AndroidRuntime(7120): at android.os.Looper.loop(Looper.java:193)
11-24 18:54:20.354: E/AndroidRuntime(7120): at android.app.ActivityThread.main(ActivityThread.java:5388)
11-24 18:54:20.354: E/AndroidRuntime(7120): at java.lang.reflect.Method.invokeNative(Native Method)
11-24 18:54:20.354: E/AndroidRuntime(7120): at java.lang.reflect.Method.invoke(Method.java:515)
11-24 18:54:20.354: E/AndroidRuntime(7120): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
11-24 18:54:20.354: E/AndroidRuntime(7120): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:655)
11-24 18:54:20.354: E/AndroidRuntime(7120): at dalvik.system.NativeStart.main(Native Method)
回答1:
Try with below code:
public class Adapter1 extends BaseAdapter implements OnClickListener {
public ArrayList<HashMap<String, String>> arr = null;
Context context = null;
LayoutInflater layoutInflater = null;
HashMap<String, String> getData = new HashMap<String, String>();
String urlLike = null;
TextView strId = null;
public NewsFeedAdapter(Context context,
ArrayList<HashMap<String, String>> arr) {
this.context = context;
this.arr= arr;
layoutInflater = LayoutInflater.from(context);
}
@Override
public int getCount() {
return arr.size();
}
@Override
public Object getItem(int position) {
return arr.get(position);
}
@Override
public long getItemId(int position) {
return position;
}
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if (convertView == null) {
convertView = layoutInflater.inflate(
R.layout.my_list_item, null);
/** initialize ViewHolder */
viewHolder = new ViewHolder();
/** Initialize Widgets */
/** Imageview */
viewHolder.imgLike = (ImageView) convertView
.findViewById(R.id.imgLike);
viewHolder.imgComments = (ImageView) convertView
.findViewById(R.id.imgComments);
viewHolder.imgComments.setOnClickListener(this);
viewHolder.imgShare = (ImageView) convertView
.findViewById(R.id.imgShare);
viewHolder.imgShare.setOnClickListener(this);
/** TextView */
viewHolder.txtId = (TextView) convertView
.findViewById(R.id.txtId);
viewHolder.txtDescription = (TextView) convertView
.findViewById(R.id.txtDescription);
getData = arr.get(position);
viewHolder.txtId.setText(getData
.get(Fragment1.TAG_ID));
viewHolder.txtDescription.setText(getData
.get(Fragment1.TAG_MESSAGE));
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
convertView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
viewHolder.imgLike.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
strId=arr.get(position).getId();//or whatever you want to do do here.
}
});
return convertView;
}
/** ViewHolder Class */
public class ViewHolder {
ImageView imgLike = null, imgComments = null,
imgShare = null;
TextView txtId = null,txtDescription = null;
}
}
回答2:
Try this:
strId = (TextView) view.getParent().findViewById(R.id.txtId);
This will fix your crash, but you need to rethink about your design.
回答3:
What u have to do is set Diff onclick Listeners on diff views
viewHolder.txtDescription.setTag(R.id.txtDescription,position);
viewHolder.txtDescription.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
int position_clicked=(Integer)v.getTag();
}
});
repeat it for every view your want to set listener
回答4:
You need to initialize strId in getView()
here in the following code, its not able to initialize it based on "view" object, hence you get nullpointer.
case R.id.imgLike:
strId = ((TextView) view.findViewById(R.id.txtId));
mark as solved if you find the answer useful.
回答5:
You can also use onClickListener inside your adapter class.
Look this sample code
viewHolder.imgLike = (ImageView) convertView.findViewById(R.id.imgLike);
viewHolder.imgLike.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
String id = getData.get(Fragment1.TAG_ID);
}
});
回答6:
try like this,
@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if (convertView == null) {
convertView = layoutInflater.inflate(
R.layout.my_list_item, null);
/** initialize ViewHolder */
viewHolder = new ViewHolder();
/** Initialize Widgets */
/** Imageview */
viewHolder.imgLike = (ImageView) convertView
.findViewById(R.id.imgLike);
viewHolder.imgLike.setOnClickListener(this);
viewHolder.imgLike.setTag(position);
viewHolder.imgComments = (ImageView) convertView
.findViewById(R.id.imgComments);
viewHolder.imgComments.setOnClickListener(this);
viewHolder.imgShare = (ImageView) convertView
.findViewById(R.id.imgShare);
viewHolder.imgShare.setOnClickListener(this);
/** TextView */
viewHolder.txtId = (TextView) convertView
.findViewById(R.id.txtId);
viewHolder.txtDescription = (TextView) convertView
.findViewById(R.id.txtDescription);
getData = arr.get(position);
viewHolder.txtId.setText(getData
.get(Fragment1.TAG_ID));
viewHolder.txtDescription.setText(getData
.get(Fragment1.TAG_MESSAGE));
convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
convertView.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
return convertView;
}
@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.imgLike:
View view = listview.getAdapter().getView(((ImageView)v).getTag(), null, listview);
txtId = (TextView) view.findViewById(R.id.txtId);
System.out.println("On Click====="
+ strId.getText().toString());
urlLike = "http://www.example.com?id="
+ strId.getText().toString() + "&user_id="
+ myDetail.getUserId();
new sendLikeData().execute();
break;
case R.id.imgComments:
break;
case R.id.imgShare:
break;
default:
break;
}
}
来源：https://stackoverflow.com/questions/27103754/how-to-get-id-of-particular-item-of-listview-in-android