E/AndroidRuntime: FATAL EXCEPTION: main error in android studio

Question

My Application is a simple counter with an add button, and reset button. When I try to run my application on the emulator, it always takes more time to install and finally show me this error message.

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.tasbeeh, PID: 7966
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.tasbeeh/com.example.tasbeeh.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.TextView.findViewById(int)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.widget.TextView.findViewById(int)' on a null object reference
        at com.example.tasbeeh.MainActivity.onCreate(MainActivity.java:24)
        at android.app.Activity.performCreate(Activity.java:7802)
        at android.app.Activity.performCreate(Activity.java:7791)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

This is my MainActivity.java

package com.example.tasbeeh;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    TextView tvCounter;
    Button add_button;
    ImageView resetButton;


    int counter = 0;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        tvCounter.findViewById(R.id.tvCounter);
        add_button.findViewById(R.id.add_button);
        resetButton.findViewById(R.id.resetButton);


        add_button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                if(counter == 0) {
                    counter = counter + 1;
                    tvCounter.setText(String.valueOf(counter));
                }
            }
        });

        resetButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                counter = 0;
            }
        });
    }
}

Does this answer your question? [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Saurabh Thorat, Feb 11 '20 at 09:40
you are doing `findViewById` incorrectly, `tvCounter = findViewById(R.id.tvCounter);` — a_local_nobody, Feb 11 '20 at 09:42

score 0 · Accepted Answer · answered Feb 11 '20 at 10:00

0

findViewById() should be used as:

tvCounter = findViewById(R.id.tvCounter);
add_button = findViewById(R.id.add_button);
resetButton = findViewById(R.id.resetButton);

answered Feb 11 '20 at 10:00

Siddharth Thakkar

376
1
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E/AndroidRuntime: FATAL EXCEPTION: main error in android studio

1 Answers1