When I try to run my app on the emulator, it's unfortunately saying app is stopped

Question

I am new on android. I have just made my first app. But as I run my my app on android emulator, it does not run. App compiled without any error, but on emulator it's showing that unfortunately app is stopped.

This is the java code:

package com.example.kartikeya;

import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{
double x,y;
static int op=0;
double result;
TextView textView = new TextView(this);
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView();

    Button button = (Button) findViewById(R.id.button);
    button.setOnClickListener(this); // calling onClick() method
    Button button2 = (Button) findViewById(R.id.button2);
    button2.setOnClickListener(this);
    //Button button3 = (Button) findViewById(R.id.button3);
   // button3.setOnClickListener(this);


    textView = (TextView) findViewById(R.id.textView);
    textView.setOnClickListener(this);
}

private void setContentView() {
}

@Override
public void onClick(View v) {

    switch (v.getId()) {

        case R.id.button:
            Button button = new Button(this);
            button.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 9);
            break;

        case R.id.button2:
            Button button2 = new Button(this);
            button2.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 8);
            break;

        case R.id.button3:
            Button button3 = new Button(this);
            button3.setBackgroundColor(Color.CYAN);
           textView.setText(textView.getText() +"" + 7);
            break;

        case R.id.button4:
            Button button4 = new Button(this);
            button4.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 6);
            break;

        case R.id.button5:
            Button button5 = new Button(this);
            button5.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 5);
            break;

        case R.id.button6:
            Button button6 = new Button(this);
            button6.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 4);
            break;

        case R.id.button7:
            Button button7 = new Button(this);
            button7.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 3);
            break;

        case R.id.button8:
            Button button8 = new Button(this);
            button8.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 2);
            break;

        case R.id.button9:
            Button button9 = new Button(this);
            button9.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 1);
            break;

        case R.id.button10:
            Button button10 = new Button(this);
            button10.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + 0);
            break;

        case R.id.button11:
            Button button11 = new Button(this);
            button11.setBackgroundColor(Color.CYAN);
            textView.setText(textView.getText() +"" + '.');
            break;



        case R.id.button13:
            x=Double.parseDouble((String)textView.getText());
            op=1;
            Button button13 = new Button(this);
            button13.setBackgroundColor(Color.CYAN);
            textView.setText(" ");
            break;

        case R.id.button14:
            x=Double.parseDouble((String)textView.getText());
            op=2;
            Button button14 = new Button(this);
            button14.setBackgroundColor(Color.CYAN);
            textView.setText(" ");
            break;

        case R.id.button15:
            x=Double.parseDouble((String)textView.getText());
            op=3;
            Button button15 = new Button(this);
            button15.setBackgroundColor(Color.CYAN);
            textView.setText(" ");
            break;

        case R.id.button16:
            x=Double.parseDouble((String)textView.getText());
            op=4;
            Button button16 = new Button(this);
            button16.setBackgroundColor(Color.CYAN);
            textView.setText(" ");
            break;
        case R.id.button12:
            y=Double.parseDouble((String) textView.getText());
            Button button12 = new Button(this);
            button12.setBackgroundColor(Color.CYAN);
            switch(op)
            {
                case 1:
                {
                    result=x+y;
                    break;
                }
                case 2:
                {
                    result=x-y;
                    break;
                }
                case 3:
                {
                    result=x*y;
                    break;
                }
                case 4:
                {
                    result=x/y;
                    break;
                }
                default :
                    break;
            }
            if(result-Math.floor(result)==0)
            {
                result=Math.floor(result);
            }
            textView.setText(result+"");
            break;

        default:
            break;
    }

}

}

This is xml file

<?xml version="1.0" encoding="utf-8"?>

<Button
    android:text="@string/button0"
    android:id="@+id/button"
    android:textColor="#0A0A0A"
    android:textSize="25sp"

    android:layout_width="80dp"
    android:layout_height="80dp"
    android:background="@drawable/buttonshape"
    android:shadowColor="#A8A8A8"
    android:shadowDx="0"
    android:shadowDy="0"

    android:layout_below="@+id/textView"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:layout_marginTop="10dp"
    android:clickable="true"
    android:contentDescription="@string/click1"
    android:contextClickable="true" />

<TextView
    android:layout_width="350dp"
    android:layout_height="100dp"
    android:textAppearance="?android:attr/textAppearanceLarge"
    android:text="@string/text1"
    android:id="@+id/textView"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:background="#ffffff" />

<Button
    android:textColor="#0A0A0A"
    android:textSize="25sp"

    android:layout_width="80dp"
    android:layout_height="80dp"
    android:background="@drawable/buttonshape"
    android:shadowColor="#A8A8A8"
    android:shadowDx="0"
    android:shadowDy="0"
    android:text="@string/button"
    android:id="@+id/button2"
    android:layout_alignTop="@+id/button"
    android:layout_toRightOf="@+id/button"
    android:layout_toEndOf="@+id/button"
    android:layout_marginLeft="2.5dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button7"
        android:id="@+id/button3"
        android:layout_alignTop="@+id/button13"
        android:layout_toRightOf="@+id/button5" />

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button6"
        android:id="@+id/button4"
        android:layout_centerVertical="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="10dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button5"
        android:id="@+id/button5"
        android:layout_alignTop="@+id/button4"
        android:layout_toRightOf="@+id/button4"
        android:layout_toEndOf="@+id/button4"
        android:layout_marginLeft="2.5dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button4"
        android:id="@+id/button6"
        android:layout_alignTop="@+id/button5"
        android:layout_toRightOf="@+id/button5" />

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button3"
        android:id="@+id/button7"
        android:layout_below="@+id/button4"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="10dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button10"
        android:id="@+id/button8"
        android:layout_below="@+id/button5"
        android:layout_alignLeft="@+id/button5"
        android:layout_alignStart="@+id/button5"
        android:layout_marginTop="10dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button11"
        android:id="@+id/button9"
        android:layout_alignTop="@+id/button15"
        android:layout_toRightOf="@+id/button8" />

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button12"
        android:id="@+id/button10"
        android:layout_below="@+id/button9"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"
        android:layout_marginTop="10dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button13"
        android:id="@+id/button11"
        android:layout_below="@+id/button9"
        android:layout_alignLeft="@+id/button8"
        android:layout_alignStart="@+id/button8"
        android:layout_marginTop="10dp"/>

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button18"
        android:id="@+id/button12"
        android:layout_alignTop="@+id/button16"
        android:layout_toRightOf="@+id/button11" />



    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"

        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button14"
        android:id="@+id/button13"
        android:layout_above="@+id/button4"
        android:layout_alignParentRight="true" />

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button15"
        android:id="@+id/button14"
        android:layout_alignTop="@+id/button6"
        android:layout_alignParentRight="true" />

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button16"
        android:id="@+id/button15"
        android:layout_alignTop="@+id/button8"
        android:layout_alignRight="@+id/textView"
        android:layout_alignEnd="@+id/textView" />

    <Button
        android:textColor="#0A0A0A"
        android:textSize="25sp"
        android:layout_width="80dp"
        android:layout_height="80dp"
        android:background="@drawable/buttonshape"
        android:shadowColor="#A8A8A8"
        android:shadowDx="0"
        android:shadowDy="0"
        android:text="@string/button17"
        android:id="@+id/button16"
        android:layout_below="@+id/button9"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:layout_marginTop="10dp"/>

This is AndroidManifest file:

<?xml version="1.0" encoding="utf-8"?>

<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme" >
    <activity android:name=".MainActivity" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
</application>

This is the LogCat

12-21 22:15:23.620 1425-1425/com.example.kartikeya.calc D/dalvikvm: Not late-enabling CheckJNI (already on)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc D/AndroidRuntime: Shutting down VM
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0xb2fed180)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime: FATAL EXCEPTION: main
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.kartikeya.calc/com.example.kartikeya.calc.MainActivity}: java.lang.NullPointerException
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1880)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.access$600(ActivityThread.java:123)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:4424)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:  Caused by: java.lang.NullPointerException
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.content.ContextWrapper.getResources(ContextWrapper.java:81)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.view.View.<init>(View.java:2696)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.view.View.<init>(View.java:2744)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.widget.TextView.<init>(TextView.java:449)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc `E/AndroidRuntime:     at android.widget.TextView.<init>(TextView.java:442)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.widget.TextView.<init>(TextView.java:437)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at com.example.kartikeya.calc.MainActivity.<init>(MainActivity.java:14)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at java.lang.Class.newInstanceImpl(Native Method)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at java.lang.Class.newInstance(Class.java:1319)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.Instrumentation.newActivity(Instrumentation.java:1023)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1871)
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.access$600(ActivityThread.java:123) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:99) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:137) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:4424) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at java.lang.reflect.Method.invokeNative(Native Method) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:511) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
12-21 22:15:23.640 1425-1425/com.example.kartikeya.calc E/AndroidRuntime:     at dalvik.system.NativeStart.main(Native Method) 
12-21 22:15:24.140 1425-1431/com.example.kartikeya.calc I/dalvikvm: threadid=3: reacting to signal 3
12-21 22:15:24.140 1425-1431/com.example.kartikeya.calc I/dalvikvm: Wrote stack traces to '/data/anr/traces.txt'
12-21 22:15:24.160 1425-1431/com.example.kartikeya.calc I/dalvikvm: threadid=3: reacting to signal 3
12-21 22:15:24.160 1425-1431/com.example.kartikeya.calc I/dalvikvm: Wrote stack traces to '/data/anr/traces.txt'
12-21 22:15:27.801 1425-1425/? I/Process: Sending signal. PID: 1425 SIG: 9

`TextView textView = new TextView(this);` can't do that at this point, the context is not initialized yet. Wait until onCreate was called. Also, you are not displaying it ever, so I don't know what you try to do with that — njzk2, Dec 21 '15 at 17:12

score 0 · Answer 1 · answered Dec 21 '15 at 17:09

Your problem is this line TextView textView = new TextView(this);

You are trying to call setText() on this view in your onClick methods, but this view hasn't been inflated. You have to inflate the view before you can manipulate it, just like you did with Button button = (Button) findViewById(R.id.button);

So in your onCreate() you would want to put in textView = (TextView) findViewById(R.id.your_text_view_id); and get rid of your TextView textView = new TextView(this); line -- just make it TextView textView;

I have use your method but nothing happen. – Kartikeya Garg Dec 22 '15 at 12:14 — Kartikeya Garg, Dec 22 '15 at 12:14

When I try to run my app on the emulator, it's unfortunately saying app is stopped

1 Answers1