Tuesday, 16 January 2018

android - App crashes on findViewById()

itemprop="text">



So I have a
ListView in my activity_main.xml. Also a TextView in a different xml
da_item.xml.
The textview is for the individual listview items.



Now in my code there is a
onContextItemSelected() function which calls
bucketMarkItem(long itemTitle).
bucketMarkItem(long itemTitle) changes the last item's
background color using function
colorCorrection().




The
whole code works fine.



But I have a button with
enterItem() onClick listener. I call the same
colorCorrection() from inside
enterItem() and the app crashes.
It crashes on
this line.



TextView
            txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);


And
I have no idea why.




I've seen many
question like this and the answer was to use
setContentView(R.layout.activity_main) but I've already
included
this.



onContextItemSelected
Code



@Override
public
            boolean onContextItemSelected(MenuItem item) {
 // TODO Auto-generated method
            stub
 super.onContextItemSelected(item);


            AdapterContextMenuInfo info = (AdapterContextMenuInfo)
            item.getMenuInfo();

 long hula = info.id;


            if(item.getTitle()=="Mark as Done"){
 bucketMarkItem(hula);

            }
 if(item.getTitle()=="Mark as Undone"){

            bucketUnMarkItem(hula);
 }
 if(item.getTitle()=="Delete
            Item"){
 bucketDeletelistItem(hula);


            }

 return
            true;
}


bucketMarkItem()
Code



private void
            bucketMarkItem(long itemTitle) {
 // TODO Auto-generated method
            stub

 View
            listItemBla=(View)list.getChildAt((int)(long)itemTitle);
 TextView
            txtDep=(TextView)listItemBla.findViewById(R.id.tv);

            txtDep.setBackgroundColor(Color.GREEN);

 String txtDepText =
            ""+txtDep.getText();
 String[] result = txtDepText.split(" ");

            String result1 = result[1];

 Cursor cursor =
            myDB.getAllRows();


 if(cursor.moveToFirst()){

            do{
 if(result1.equals(cursor.getString(1))){
 long yourDBID =
            yourDB.insertRow(cursor.getInt(0));
 }

            }while(cursor.moveToNext());
 }
 cursor.close();

            colorCorrecton();
}



colorCorrecton
Code



private void
            colorCorrecton() {

 Toast.makeText(MainActivity.this,""+
            list.getCount(), Toast.LENGTH_SHORT).show();

 View
            listItemBla1=(View)list.getChildAt((list.getCount()-1));
 TextView
            txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);



            Toast.makeText(MainActivity.this, ""+txtDep1.getText(),
            Toast.LENGTH_SHORT).show();

            txtDep.setBackgroundColor(Color.GREEN);
}


enterItem()
Code



public void
            enterItem(View v) {
// TODO Auto-generated method
            stub

EditText
            dataEntry_EditText=(EditText)findViewById(R.id.editText1);
Editable
            dataEntry_Editable = dataEntry_EditText.getText();
String dataEntry_Finaldata
            = dataEntry_Editable.toString();
long newId =
            myDB.insertRow(dataEntry_Finaldata, 233,
            "red");

//Toast.makeText(MainActivity.this, dataEntry_Finaldata,
            Toast.LENGTH_LONG).show();
dataEntry_EditText.setText("");

populateListView();


//Toast.makeText(MainActivity.this,
            ""+list.getCount(),
            Toast.LENGTH_LONG).show();
colorCorrecton();
}


Complete
Code



package
            com.example.bucketlist;

 import
            java.util.ArrayList;


 import
            android.support.v4.app.FragmentActivity;
 import
            android.text.Editable;
 import android.database.Cursor;
 import
            android.graphics.Color;
 import android.os.Bundle;
 import
            android.view.ContextMenu;
 import android.view.MenuItem;
 import
            android.view.View;
 import
            android.view.ContextMenu.ContextMenuInfo;

 import
            android.widget.AdapterView.AdapterContextMenuInfo;
 import
            android.widget.ArrayAdapter;
 import android.widget.EditText;

            import android.widget.ImageView;
 import android.widget.ListView;

            import android.widget.TextView;
 import
            android.widget.Toast;

 public class MainActivity extends
            FragmentActivity {


ListView list;
DBAdapter
            myDB;
DBAdapter1 yourDB;

@Override
protected
            void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_main);

 ImageView bucketMenu =
            (ImageView)findViewById(R.id.bucketMenuW);

 list=
            (ListView)findViewById(R.id.listView1);

            registerForContextMenu(list);
 openDB();

            populateListView();

            //colorCorrecton();

}

private void
            colorCorrecton() {


 Toast.makeText(MainActivity.this,""+
            list.getCount(), Toast.LENGTH_SHORT).show();

 View
            listItemBla1=(View)list.getChildAt((list.getCount()-1));
 TextView
            txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);


            Toast.makeText(MainActivity.this, ""+txtDep1.getText(),
            Toast.LENGTH_SHORT).show();

            //txtDep.setBackgroundColor(Color.GREEN);
}

public void
            conMenu(View v) {

 // TODO Auto-generated method
            stub
}

@Override
public void
            onCreateContextMenu(ContextMenu menu, View v,
 ContextMenuInfo menuInfo)
            {
 // TODO Auto-generated method stub

            super.onCreateContextMenu(menu, v, menuInfo);


            if(v.getId()==R.id.listView1){

 menu.add("Mark as
            Done");
 menu.add("Mark as Undone");
 menu.add("Delete
            Item");
 }
}

@Override
public boolean
            onContextItemSelected(MenuItem item) {
 // TODO Auto-generated method
            stub
 super.onContextItemSelected(item);



            AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();

            long hula = info.id;

 if(item.getTitle()=="Mark as
            Done"){
 bucketMarkItem(hula);
 }

            if(item.getTitle()=="Mark as Undone"){
 bucketUnMarkItem(hula);

            }

 if(item.getTitle()=="Delete Item"){

            bucketDeletelistItem(hula);
 }

 return
            true;
}

private void bucketUnMarkItem(long itemTitle)
            {
 // TODO Auto-generated method stub
 View
            listItemBla=(View)list.getChildAt((int)(long)itemTitle);

 TextView
            txtDep=(TextView)listItemBla.findViewById(R.id.tv);
 String txtDepText =
            ""+txtDep.getText();
 String[] result = txtDepText.split(" ");

            String result1 = result[1];

 Cursor cursor =
            myDB.getAllRows();

 int markID=0;

            if(cursor.moveToFirst()){
 do{


            if(result1.equals(cursor.getString(1))){
 markID =
            cursor.getInt(0);
 }
 }while(cursor.moveToNext());

            }
 cursor.close();
 //Toast.makeText(MainActivity.this,
            ""+list.getCount(), Toast.LENGTH_LONG).show();

 Cursor cursor1 =
            yourDB.getAllRows();



            if(cursor1.moveToFirst()){
 do{
 if(markID ==
            cursor1.getInt(1)){
 boolean newid2 =
            yourDB.deleteRow(cursor1.getInt(0));
 }

            }while(cursor1.moveToNext());
 }

            cursor1.close();


            colorCorrecton();

}

private void
            bucketMarkItem(long itemTitle) {
 // TODO Auto-generated method
            stub
 View listItemBla=(View)list.getChildAt((int)(long)itemTitle);

            TextView txtDep=(TextView)listItemBla.findViewById(R.id.tv);

            txtDep.setBackgroundColor(Color.GREEN);

 String txtDepText =
            ""+txtDep.getText();
 String[] result = txtDepText.split("
            ");

 String result1 = result[1];

 Cursor
            cursor = myDB.getAllRows();

 if(cursor.moveToFirst()){

            do{
 if(result1.equals(cursor.getString(1))){
 long yourDBID =
            yourDB.insertRow(cursor.getInt(0));
 }

            }while(cursor.moveToNext());

 }

            cursor.close();
}

public void deleteItem(View v)
            {
 // TODO Auto-generated method stub
 myDB.deleteAll();

            yourDB.deleteAll();

            populateListView();
}


private void
            bucketDeletelistItem(long itemTitle) {
 View
            listItemBla=(View)list.getChildAt((int)(long)itemTitle);
 TextView
            txtDep=(TextView)listItemBla.findViewById(R.id.tv);
 String txtDepText =
            ""+txtDep.getText();
 String[] result = txtDepText.split(" ");

            String result1 = result[1];

 Cursor cursor =
            myDB.getAllRows();


 int markID=0;

            if(cursor.moveToFirst()){
 do{

            if(result1.equals(cursor.getString(1))){
 boolean newid1 =
            myDB.deleteRow(cursor.getInt(0));
 markID = cursor.getInt(0);

            }
 }while(cursor.moveToNext());
 }

            cursor.close();

 populateListView();

            //Toast.makeText(MainActivity.this, ""+list.getCount(),
            Toast.LENGTH_LONG).show();

 Cursor cursor1 =
            yourDB.getAllRows();

 if(cursor1.moveToFirst()){

            do{
 if(markID == cursor1.getInt(1)){
 boolean newid2 =
            yourDB.deleteRow(cursor1.getInt(0));
 }


            }while(cursor1.moveToNext());
 }

            cursor1.close();


            colorCorrecton();
}

public void enterItem(View v)
            {
 // TODO Auto-generated method stub
 EditText
            dataEntry_EditText=(EditText)findViewById(R.id.editText1);


            Editable dataEntry_Editable = dataEntry_EditText.getText();
 String
            dataEntry_Finaldata = dataEntry_Editable.toString();
 long newId =
            myDB.insertRow(dataEntry_Finaldata, 233, "red");


            //Toast.makeText(MainActivity.this, dataEntry_Finaldata,
            Toast.LENGTH_LONG).show();

            dataEntry_EditText.setText("");


            populateListView();

 //Toast.makeText(MainActivity.this,
            ""+list.getCount(), Toast.LENGTH_LONG).show();


            colorCorrecton();
}

@Override
protected void
            onDestroy() {
 // TODO Auto-generated method stub

            super.onDestroy();

            closeDB();
}


private void closeDB()
            {
 // TODO Auto-generated method stub

            myDB.close();
}

private void openDB() {
 //
            TODO Auto-generated method stub
 myDB = new DBAdapter(this);
 yourDB
            = new DBAdapter1(this);
 myDB.open();


            yourDB.open();
}

private void populateListView()
            {
 // TODO Auto-generated method stub

 Cursor cursor =
            myDB.getAllRows();
 ArrayList myItems = new
            ArrayList();
 //String[] myItems =
            {};


 if(cursor.moveToFirst()){
 int
            countData=0;
 do{
 countData=countData+1;
 int id =
            cursor.getInt(0);
 String name = "#"+countData +"- "+
            cursor.getString(1);
 myItems.add(name);

            }while(cursor.moveToNext());
 }

            cursor.close();


 ArrayAdapter adapter =
            new ArrayAdapter(this,R.layout.da_item,myItems);


            list.setAdapter(adapter);

 //Toast.makeText(MainActivity.this,
            Integer.toString(list.getFirstVisiblePosition())+","+Integer.toString(list.getLastVisiblePosition()),
            Toast.LENGTH_LONG).show();
 //View v = list.getChildAt(0);

            //v.setBackgroundColor(005566);
 //View
            listItemBla=(View)list.getChildAt(list.getFirstVisiblePosition());

            //Toast.makeText(MainActivity.this, ""+ list.getChildCount(),
            Toast.LENGTH_LONG).show();

 //TextView
            txtDep=(TextView)listItemBla.findViewById(R.id.tv);

            //txtDep.setBackgroundColor(Color.parseColor("00FF00"));
}

}


Logcat




            06-21 09:46:13.656: D/libEGL(24175): loaded
            /system/lib/egl/libEGL_adreno200.so

 06-21 09:46:13.656:
            D/libEGL(24175): loaded /system/lib/egl/libGLESv1_CM_adreno200.so
 06-21
            09:46:13.656: D/libEGL(24175): loaded /system/lib/egl/libGLESv2_adreno200.so

            06-21 09:46:13.666: I/Adreno200-EGL(24175): : EGL
            1.4 QUALCOMM build:
            AU_LINUX_ANDROID_JB_2.5.04.02.02.040.400_msm8960_JB_2.5_CL3744273_release_AU
            (CL3744273)
 06-21 09:46:13.666: I/Adreno200-EGL(24175): Build Date: 06/30/13
            Sun
 06-21 09:46:13.666: I/Adreno200-EGL(24175): Local Branch: 

            06-21 09:46:13.666: I/Adreno200-EGL(24175): Remote Branch: quic/jb_2.5
 06-21
            09:46:13.666: I/Adreno200-EGL(24175): Local Patches: NONE
 06-21 09:46:13.666:
            I/Adreno200-EGL(24175): Reconstruct Branch: AU_LINUX_ANDROID_JB_2.5.04.02.02.040.400 +
            NOTHING
 06-21 09:46:13.706: D/OpenGLRenderer(24175): Enabling debug mode
            0
 06-21 09:46:24.217: D/AndroidRuntime(24175): Shutting down
            VM

 06-21 09:46:24.217: W/dalvikvm(24175): threadid=1: thread
            exiting with uncaught exception (group=0x40c12ae0)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): FATAL EXCEPTION: main
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): java.lang.IllegalStateException: Could not execute method of
            the activity
 06-21 09:46:24.217: E/AndroidRuntime(24175): at
            android.view.View$1.onClick(View.java:3673)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at android.view.View.performClick(View.java:4278)

            06-21 09:46:24.217: E/AndroidRuntime(24175): at
            android.view.View$PerformClick.run(View.java:17429)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at
            android.os.Handler.handleCallback(Handler.java:725)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at
            android.os.Handler.dispatchMessage(Handler.java:92)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at android.os.Looper.loop(Looper.java:137)
 06-21
            09:46:24.217: E/AndroidRuntime(24175): at
            android.app.ActivityThread.main(ActivityThread.java:5099)

 06-21
            09:46:24.217: E/AndroidRuntime(24175): at java.lang.reflect.Method.invokeNative(Native
            Method)
 06-21 09:46:24.217: E/AndroidRuntime(24175): at
            java.lang.reflect.Method.invoke(Method.java:511)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at
            com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:803)

            06-21 09:46:24.217: E/AndroidRuntime(24175): at
            com.android.internal.os.ZygoteInit.main(ZygoteInit.java:570)
 06-21
            09:46:24.217: E/AndroidRuntime(24175): at dalvik.system.NativeStart.main(Native
            Method)
 06-21 09:46:24.217: E/AndroidRuntime(24175): Caused by:
            java.lang.reflect.InvocationTargetException
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at java.lang.reflect.Method.invokeNative(Native
            Method)
 06-21 09:46:24.217: E/AndroidRuntime(24175): at
            java.lang.reflect.Method.invoke(Method.java:511)
 06-21 09:46:24.217:
            E/AndroidRuntime(24175): at android.view.View$1.onClick(View.java:3668)
 06-21
            09:46:24.217: E/AndroidRuntime(24175): ... 11 more

 06-21
            09:46:24.217: E/AndroidRuntime(24175): Caused by:
            java.lang.NullPointerException
 06-21 09:46:24.217: E/AndroidRuntime(24175):
            at com.example.bucketlist.MainActivity.colorCorrecton(MainActivity.java:47)

            06-21 09:46:24.217: E/AndroidRuntime(24175): at
            com.example.bucketlist.MainActivity.enterItem(MainActivity.java:204)
 06-21
            09:46:24.217: E/AndroidRuntime(24175): ... 14 more
 06-21 09:46:26.069:
            I/Process(24175): Sending signal. PID: 24175 SIG:
            9

itemprop="text">
class="normal">Answer



The
problem is, using



TextView
            txtDep1=(TextView)listItemBla1.findViewById(R.id.tv);



is
telling the system to look inside of listItemBla1 for a View
with an id of tv which it obviously won't find because no
View can exist inside your ListView
(at least not how you expect it to).



What you
need to do is create a custom adapter and override getView()
where you can inflate the layout with the TextView you
want.


-

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