Develop Reference

How can I solve the problem with the OnClick?

E/AndroidRuntime: FATAL EXCEPTION: main
Process: andoid.example.taxiluks, PID: 5627
java.lang.IllegalStateException: Could not execute method for android:onClick
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:414)
at android.view.View.performClick(View.java:6320)
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992)
at android.view.View$PerformClick.run(View.java:25087)
at android.os.Handler.handleCallback(Handler.java:869)
at android.os.Handler.dispatchMessage(Handler.java:101)
at android.os.Looper.loop(Looper.java:206)
at android.app.ActivityThread.main(ActivityThread.java:6749)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:845)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409)
at android.view.View.performClick(View.java:6320) 
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992) 
at android.view.View$PerformClick.run(View.java:25087) 
at android.os.Handler.handleCallback(Handler.java:869) 
at android.os.Handler.dispatchMessage(Handler.java:101) 
at android.os.Looper.loop(Looper.java:206) 
at android.app.ActivityThread.main(ActivityThread.java:6749) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:845) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.widget.EditText com.google.android.material.textfield.TextInputLayout.getEditText()' on a null object reference
at andoid.example.taxiluks.PassengerSingInActivity.validateEmail(PassengerSingInActivity.java:73)
at andoid.example.taxiluks.PassengerSingInActivity.passengerCreateLogIn(PassengerSingInActivity.java:130)
at java.lang.reflect.Method.invoke(Native Method) 
at androidx.appcompat.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:409) 
at android.view.View.performClick(View.java:6320) 
at com.google.android.material.button.MaterialButton.performClick(MaterialButton.java:992) 
at android.view.View$PerformClick.run(View.java:25087) 
at android.os.Handler.handleCallback(Handler.java:869) 
at android.os.Handler.dispatchMessage(Handler.java:101) 
at android.os.Looper.loop(Looper.java:206) 
at android.app.ActivityThread.main(ActivityThread.java:6749) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.Zygote$MethodAndArgsCaller.run(Zygote.java:240) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:845) 

App Crashing on starting the activity, Caused by: kotlin.a

first time getting below exception on activity startup & could not find out what is the cause.any help will be appreciated.
08-24 11:05:01.218 16287-16287/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.myproject, PID: 16287
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myproject/com.myproject.common.calendar.CalendarMainActivity}: kotlin.a
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2659)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2720)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1466)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6111)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: kotlin.a
at com.myproject.common.calendar.CalendarMainActivity.R(SourceFile:79)
at com.myproject.common.calendar.CalendarMainActivity.m(SourceFile:73)
at com.myproject.common.activity.a.setContentView(SourceFile:90)
at com.myproject.common.calendar.CalendarMainActivity.onCreate(SourceFile:47)
at android.app.Activity.performCreate(Activity.java:6734)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2612)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2720) 
at android.app.ActivityThread.-wrap12(ActivityThread.java) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1466) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6111) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755) 

Change RadioButton image in fragment from the activity

I want to change the radio button images in the fragment when a button in the activity is clicked, so I am trying to call a method in my fragment that change the images but it is not working, this is my code:
My Fragment:
public class ChoicesFragment extends Fragment {
RadioButton rd1;
RadioButton rd2;
RadioButton rd3;
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {
View view = inflater.inflate(R.layout.fragment_choices, container, false);
rd1=(RadioButton) view.findViewById(R.id.choice1);
rd2=(RadioButton) view.findViewById(R.id.choice2);
rd3=(RadioButton) view.findViewById(R.id.choice3);
return view;
}
public void setRadioButtonsImages(int choix1, int choix2, int choix3){
rd1.setButtonDrawable(choix1);
rd2.setButtonDrawable(choix2);
rd3.setButtonDrawable(choix3);
}
}
And in my activity:
public void showImages(View view) {
android.support.v4.app.FragmentTransaction transaction = getSupportFragmentManager().beginTransaction();
cf = new ChoicesFragment();
transaction.replace(R.id.container2, cf,"choicesFragment").addToBackStack(null).commit();
Resources res = getResources();
int choix1 = res.getIdentifier(level.getChoix1(),"drawable",getPackageName());
int choix2 = res.getIdentifier(level.getChoix2(),"drawable",getPackageName());
int choix3 = res.getIdentifier(level.getChoix3(),"drawable",getPackageName());
cf.setRadioButtonImage(choix1,choix2,choix3);
}
And I get this error
04-25 12:39:28.734 29413-29413/com.example.mireille.test E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mireille.test, PID: 29413
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:5637)
at android.view.View$PerformClick.run(View.java:22429)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6119)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:5637) 
at android.view.View$PerformClick.run(View.java:22429) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.RadioButton.setButtonDrawable(int)' on a null object reference
at com.example.mireille.simplegame.ChoicesFragment.setRadioButtonImage(ChoicesFragment.java:37)
at com.example.mireille.simplegame.MainActivity.changeLevel(MainActivity.java:60)
at com.example.mireille.simplegame.MainActivity.startRotatingImage(MainActivity.java:48)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:5637) 
at android.view.View$PerformClick.run(View.java:22429) 
at android.os.Handler.handleCallback(Handler.java:751) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:154) 
at android.app.ActivityThread.main(ActivityThread.java:6119) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776) 
Thanks

android ListView mListView.getChildAt(i) can't be get, how to solve it?

I created the code below to get the contents of multiple EditText:
Integer data[] = new Integer[4];
ListView listView = (ListView) findViewById(R.id.listView);
for (i=0;i < listView.getCount();i++){
LinearLayout layout = (LinearLayout) listView.getChildAt(i);
EditText et = (EditText) layout.findViewById(R.id.record_list_edit);
data[i] = Integer.parseInt(et.getText().toString());
}
I can successfully use the following code to to get just the first number (or whichever one I want):
LinearLayout layout = (LinearLayout) listView.getChildAt(0);
EditText et = (EditText) layout.findViewById(R.id.record_list_edit);
data[0] = Integer.parseInt(et.getText().toString());
But when I use the for loop to get all, it breaks.
This is the error log:
08-28 22:12:33.931 7814-7814/edu.nankai.soar.demof E/AndroidRuntime: FATAL EXCEPTION: main
Process: edu.nankai.soar.demof, PID: 7814
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:293)
at android.view.View.performClick(View.java:4851)
at android.view.View$PerformClick.run(View.java:20016)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5506)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:952)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288)
at android.view.View.performClick(View.java:4851) 
at android.view.View$PerformClick.run(View.java:20016) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5506) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:952) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747) 
Caused by: java.lang.ArrayIndexOutOfBoundsException: length=4; index=4
at edu.nankai.soar.demof.SensorsActivity.log(SensorsActivity.java:81)
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:288) 
at android.view.View.performClick(View.java:4851) 
at android.view.View$PerformClick.run(View.java:20016) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:135) 
at android.app.ActivityThread.main(ActivityThread.java:5506) 
at java.lang.reflect.Method.invoke(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:372) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:952) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747) 

Really thank you， Shaishav
Integer data[] = new Integer[listView.getCount()];
I know why I was wrong. I I counted the wrong number... I was so stupid...
The answer comes form Shaishav.

Creating an SQLite when an onClick function is called

I want to connect my application with an SQLite database. Whenever someone clicks on the create button, the database should be generated immediately. I'm using the onClick function, but I'm getting an error when the function is called. This is the code that is executed when the onClick function is called:
public void createDb(View view)
{
DataHandler db = new DataHandler(this);
db.addValue();
Toast.makeText(getApplicationContext(),"DataBase Created Successfully.", Toast.LENGTH_SHORT).show();
}
The function addValue is defined in the DataHandler class with the following code:
void addValue()
{
SQLiteDatabase db = this.getWritableDatabase();
ContentValues values=new ContentValues();
Random rand=new Random();
//for (int i=0;i<15;i++)
{
values.put(KEY_VALUE,rand.nextInt(2));
db.insert(TABLE_DATA,null,values);
}
db.close();
return ;
}
I'm getting this error:
06-18 09:19:33.429 3200-3200/com.example.mobileworkstation.database E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.mobileworkstation.database, PID: 3200
java.lang.IllegalStateException: Could not execute method for android:onClick
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:289)
at android.view.View.performClick(View.java:5198)
at android.view.View$PerformClick.run(View.java:21147)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:148)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invoke(Native Method)
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284)
at android.view.View.performClick(View.java:5198) 
at android.view.View$PerformClick.run(View.java:21147) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
Caused by: android.database.sqlite.SQLiteException: near "TABLEDATA": syntax error (code 1): , while compiling: CREATE TABLEDATA(VALUEINTEGER )
at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method)
at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:887)
at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:498)
at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588)
at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:58)
at android.database.sqlite.SQLiteStatement.<init>(SQLiteStatement.java:31)
at android.database.sqlite.SQLiteDatabase.executeSql(SQLiteDatabase.java:1674)
at android.database.sqlite.SQLiteDatabase.execSQL(SQLiteDatabase.java:1605)
at com.example.mobileworkstation.database.DataHandler.onCreate(DataHandler.java:28)
at android.database.sqlite.SQLiteOpenHelper.getDatabaseLocked(SQLiteOpenHelper.java:251)
at android.database.sqlite.SQLiteOpenHelper.getWritableDatabase(SQLiteOpenHelper.java:163)
at com.example.mobileworkstation.database.DataHandler.addValue(DataHandler.java:38)
at com.example.mobileworkstation.database.MainActivity.createDb(MainActivity.java:71)
at java.lang.reflect.Method.invoke(Native Method) 
at android.support.v7.app.AppCompatViewInflater$DeclaredOnClickListener.onClick(AppCompatViewInflater.java:284) 
at android.view.View.performClick(View.java:5198) 
at android.view.View$PerformClick.run(View.java:21147) 
at android.os.Handler.handleCallback(Handler.java:739) 
at android.os.Handler.dispatchMessage(Handler.java:95) 
at android.os.Looper.loop(Looper.java:148) 
at android.app.ActivityThread.main(ActivityThread.java:5417) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:726) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:616) 
I have read through many tutorials but I still cannot seem to get it to work. Any suggestions on how to solve this?