从ListView获取视图

Question

I have to find the coordinates of a ImageView inside my ListView but I can't make it. I have tried with getItemAtPosition() but the APP crashes. Each ImageView has a different tag and in each row of my ListView.

My function:

ListView listStudents = (ListView) findViewById(R.id.listStudents);
View view = (View) listStudents.getItemAtPosition(0);

This is my ListViewAdapter:

private ArrayList<HashMap<String,String>> list = new ArrayList<HashMap<String,String>>();


public ListViewAdapter(Context context, ArrayList<HashMap<String,String>> items) {
     mContext = context;
     this.list = items;
}

public int getCount() {
     return list.size();
}

@Override
public Object getItem(int position) {
     return list.get(position);
}

public long getItemId(int position) {
     return position;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder holder = new ViewHolder();

if (convertView == null) {
    LayoutInflater inflater = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    convertView = inflater.inflate(R.layout.row_layout, null);

    /*
     * Button 1
     */
    holder.imageStudent   = (ImageView)convertView.findViewById(R.id.firstStudentImage);
    holder.imageStudent.setAlpha(50);
    holder.imageStudent.setOnClickListener(this);
    holder.imageStudent.setTag(this.numElements);
    holder.nameStudent   = (TextView)convertView.findViewById(R.id.firstStudentName);

    /*
     * Button 2
     */
    holder.imageStudent2   = (ImageView)convertView.findViewById(R.id.secondStudentImage);
    holder.imageStudent2.setAlpha(50);
    holder.imageStudent2.setOnClickListener(this);
    holder.imageStudent2.setTag(this.numElements+1);
    holder.nameStudent2   = (TextView)convertView.findViewById(R.id.secondStudentName);


    /*
     * Button 3
     */
    holder.imageStudent3   = (ImageView)convertView.findViewById(R.id.thirdStudentImage);
    holder.imageStudent3.setAlpha(50);
    holder.nameStudent3 = (TextView)convertView.findViewById(R.id.thirdStudentName);
    holder.imageStudent3.setTag(this.numElements+2);
    holder.imageStudent3.setOnClickListener(this);


    holder.imageStudent4   = (ImageView)convertView.findViewById(R.id.fourthStudentImage);
    holder.imageStudent4.setAlpha(50);
    holder.nameStudent4 = (TextView)convertView.findViewById(R.id.fourthStudentName);
    long value = 2723250804L;
    holder.imageStudent4.setTag(value);
    holder.imageStudent4.setOnClickListener(this);

    /*
     * Button 5
     */
    holder.imageStudent5   = (ImageView)convertView.findViewById(R.id.fivethStudentImage);
    holder.imageStudent5.setAlpha(50);
    holder.nameStudent5   = (TextView)convertView.findViewById(R.id.fivethStudentName);
    holder.imageStudent5.setTag(this.numElements+4);
    holder.imageStudent5.setOnClickListener(this);

    /*
     * Button 6
     */
    holder.imageStudent6   = (ImageView)convertView.findViewById(R.id.sixthStudentImage);
    holder.imageStudent6.setAlpha(50);
    holder.nameStudent6   = (TextView)convertView.findViewById(R.id.sixthStudentName);
    holder.imageStudent6.setTag(this.numElements+5);
    holder.imageStudent6.setOnClickListener(this);


    convertView.setTag(holder);

    int  idImage = this.mContext.getResources().getIdentifier(this.list.get(position).get("studentImage"),"drawable", this.mContext.getPackageName());
    Drawable myDrawable = this.mContext.getResources().getDrawable(idImage);
    holder.imageStudent.setImageDrawable(myDrawable);
    holder.nameStudent.setText(this.list.get(position).get("studentName"));


    idImage = this.mContext.getResources().getIdentifier(this.list.get(position).get("studentImage2"),"drawable", this.mContext.getPackageName());
    myDrawable = this.mContext.getResources().getDrawable(idImage);
    holder.imageStudent2.setImageDrawable(myDrawable);
    holder.nameStudent2.setText(this.list.get(position).get("studentName2"));

    idImage = this.mContext.getResources().getIdentifier(this.list.get(position).get("studentImage3"),"drawable", this.mContext.getPackageName());
    myDrawable = this.mContext.getResources().getDrawable(idImage);
    holder.imageStudent3.setImageDrawable(myDrawable);
    holder.nameStudent3.setText(this.list.get(position).get("studentName3"));

    idImage = this.mContext.getResources().getIdentifier(this.list.get(position).get("studentImage4"),"drawable", this.mContext.getPackageName());
    myDrawable = this.mContext.getResources().getDrawable(idImage);
    holder.imageStudent4.setImageDrawable(myDrawable);
    holder.nameStudent4.setText(this.list.get(position).get("studentName4"));

    idImage = this.mContext.getResources().getIdentifier(this.list.get(position).get("studentImage5"),"drawable", this.mContext.getPackageName());
    myDrawable = this.mContext.getResources().getDrawable(idImage);
    holder.imageStudent5.setImageDrawable(myDrawable);
    holder.nameStudent5.setText(this.list.get(position).get("studentName5"));

    idImage = this.mContext.getResources().getIdentifier(this.list.get(position).get("studentImage6"),"drawable", this.mContext.getPackageName());
    myDrawable = this.mContext.getResources().getDrawable(idImage);
    holder.imageStudent6.setImageDrawable(myDrawable);
    holder.nameStudent6.setText(this.list.get(position).get("studentName3"));
}
else
{
    holder = (ViewHolder)convertView.getTag();
}


return convertView;
}

@SuppressWarnings("deprecation")
@Override
public void onClick(View v) {
    EventActivity.currentButton = (Integer) v.getTag();
Activity activity = (Activity) mContext;
activity.showDialog(1);
EventActivity.currentView = (View) v.getParent();
}

This is my row_layout.xml

<?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="match_parent"
    android:layout_marginLeft="40dp"
    android:layout_marginRight="10dp"
    android:orientation="horizontal" >
<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:layout_marginRight="40dp"  
    android:layout_marginLeft="20dp"
    >
    <ImageView 
        android:id="@+id/firstStudentImage"
        android:contentDescription="@string/test"
        android:maxWidth="250dp"    
        android:maxHeight="150dp"
        android:layout_width="81dp"
        android:layout_height="115dp"
        >
    </ImageView>
    <TextView
        android:id="@+id/firstStudentName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:textIsSelectable="false">
    </TextView>

    <Button
        android:id="@+id/firstStudentButton"
        android:layout_width="81dp"
        android:layout_height="wrap_content"
        android:background="@color/attendance_no_data"
        android:textColor="@color/settings_text_color"
        android:text="@string/attendance_no_data" >
    </Button>
</LinearLayout>

    <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginRight="40dp"   
    android:orientation="vertical">
    <ImageView 
        android:id="@+id/secondStudentImage"
        android:contentDescription="@string/test"
        android:maxWidth="250dp"    
        android:maxHeight="150dp"
        android:layout_width="81dp"
        android:layout_height="115dp"
        >
    </ImageView>
    <TextView
        android:id="@+id/secondStudentName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:textIsSelectable="false">
    </TextView>
    <Button
        android:id="@+id/firstStudentButton"
        android:layout_width="81dp"
        android:layout_height="wrap_content"
        android:background="@color/attendance_no_data"
        android:textColor="@color/settings_text_color"
        android:text="@string/attendance_no_data" >
    </Button>
</LinearLayout>

    <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginRight="40dp"  
    android:orientation="vertical">
    <ImageView 
        android:id="@+id/thirdStudentImage"
        android:contentDescription="@string/test"
        android:maxWidth="250dp"    
        android:maxHeight="150dp"
        android:layout_width="81dp"
        android:layout_height="115dp"
        >
    </ImageView>
    <TextView
        android:id="@+id/thirdStudentName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:textIsSelectable="false">
    </TextView>
    <Button
        android:id="@+id/firstStudentButton"
        android:layout_marginLeft="25dp"
        android:layout_width="81dp"
        android:layout_height="wrap_content"
        android:background="@color/attendance_no_data"
        android:textColor="@color/settings_text_color"
        android:text="@string/attendance_no_data" >
    </Button>
</LinearLayout>

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:layout_marginRight="40dp"  
                android:orientation="vertical">
    <ImageView 
        android:id="@+id/fourthStudentImage"
        android:contentDescription="@string/test"
        android:maxWidth="250dp"    
        android:maxHeight="150dp"
        android:layout_width="81dp"
        android:layout_height="115dp"
        >
    </ImageView>
    <TextView
        android:id="@+id/fourthStudentName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:textIsSelectable="false">
    </TextView>
    <Button
        android:id="@+id/firstStudentButton"
        android:layout_marginLeft="25dp"
        android:layout_width="81dp"
        android:layout_height="wrap_content"
        android:background="@color/attendance_no_data"
        android:textColor="@color/settings_text_color"
        android:text="@string/attendance_no_data" >
    </Button>
</LinearLayout>

<LinearLayout
    android:layout_width="match_parent"
         android:layout_height="match_parent"
     android:layout_marginRight="40dp"
         android:orientation="vertical">
    <ImageView 
        android:id="@+id/fivethStudentImage"
        android:contentDescription="@string/test"
        android:maxWidth="250dp"    
        android:maxHeight="150dp"
        android:layout_width="81dp"
        android:layout_height="115dp">
    </ImageView>
    <TextView
        android:id="@+id/fivethStudentName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:textIsSelectable="false">
    </TextView>
    <Button
        android:id="@+id/firstStudentButton"
        android:layout_marginLeft="25dp"
        android:layout_width="81dp"
        android:layout_height="wrap_content"
        android:background="@color/attendance_no_data"
        android:textColor="@color/settings_text_color"
        android:text="@string/attendance_no_data" >
    </Button>
</LinearLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_marginRight="40dp"
    android:orientation="vertical">
    <ImageView 
        android:id="@+id/sixthStudentImage"
        android:contentDescription="@string/test"
        android:maxWidth="250dp"    
        android:maxHeight="150dp"
            android:layout_width="81dp"
        android:layout_height="115dp">
    </ImageView>
    <TextView
        android:id="@+id/sixthStudentName"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textSize="22sp"
        android:textIsSelectable="false">
    </TextView>
    <Button
        android:id="@+id/firstStudentButton"
        android:layout_marginLeft="25dp"
        android:layout_width="81dp"
        android:layout_height="wrap_content"
        android:background="@color/attendance_no_data"
        android:textColor="@color/settings_text_color"
        android:text="@string/attendance_no_data" >
    </Button>
</LinearLayout>

This is the error:

    04-05 15:57:46.238: E/AndroidRuntime(22906): FATAL EXCEPTION: main
04-05 15:57:46.238: E/AndroidRuntime(22906): java.lang.ClassCastException: java.lang.Integer cannot be cast to com.nsts.eventmarker.ListViewAdapter$ViewHolder
04-05 15:57:46.238: E/AndroidRuntime(22906):    at com.nsts.eventmarker.ListViewAdapter.getView(ListViewAdapter.java:187)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.AbsListView.obtainView(AbsListView.java:2143)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.ListView.measureHeightOfChildren(ListView.java:1246)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.ListView.onMeasure(ListView.java:1158)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.View.measure(View.java:15513)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1404)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:695)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.View.measure(View.java:15513)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.View.measure(View.java:15513)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.LinearLayout.measureVertical(LinearLayout.java:847)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.LinearLayout.onMeasure(LinearLayout.java:588)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.View.measure(View.java:15513)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:4827)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.widget.FrameLayout.onMeasure(FrameLayout.java:310)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at com.android.internal.policy.impl.PhoneWindow$DecorView.onMeasure(PhoneWindow.java:2176)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.View.measure(View.java:15513)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:1874)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1089)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1265)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:989)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:4351)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.Choreographer$CallbackRecord.run(Choreographer.java:749)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.Choreographer.doCallbacks(Choreographer.java:562)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.Choreographer.doFrame(Choreographer.java:532)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:735)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.os.Handler.handleCallback(Handler.java:725)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.os.Handler.dispatchMessage(Handler.java:92)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.os.Looper.loop(Looper.java:137)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at android.app.ActivityThread.main(ActivityThread.java:5039)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at java.lang.reflect.Method.invokeNative(Native Method)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at java.lang.reflect.Method.invoke(Method.java:511)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-05 15:57:46.238: E/AndroidRuntime(22906):    at dalvik.system.NativeStart.main(Native Method)

Answer 1

it's a ClassCastException

EventActivity.currentButton = (Integer) v.getTag(); 

i think error is on this line

long value = 2723250804L;

this is long value and you are setting this as tag and then you are trying to convert this long to integer . I think which is not possible

Actually v.getTag(); returns object .And you are trying to convert object to Integer . i are you sure v.getTag(); returns integer . Then only it works ( Refer )

what is this data type of EventActivity.currentButton ??

Answer 2

Check out this post . I think it answers your question of how to get a view by using the setTag and getTag methods to find something at a specific position.

The error is a ClassCastException . It is either occuring where you cast the tag id to a ViewHolder at the end of your code or where you are casting the view tag to an Integer . Look at the example above and set up the code that way to avoid this error.