Intent button in Android Studio crashes the app

Question

I am trying to make a button that goes into another activity but every time I press it the app crashes Here is the code from my MainActivity.java file:

package com.example.noot_a_normal_pc.kmtomiles;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;
import static android.widget.Toast.makeText;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    Button buttonBegin, buttonExit;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        buttonBegin = (Button) findViewById(R.id.begin);
        buttonBegin.setOnClickListener(this);
        buttonExit = (Button) findViewById(R.id.exit);
        buttonExit.setOnClickListener(this);
    }

    @Override
    public void onClick(View v) {
        if (v.equals(buttonExit)) {
            Toast.makeText(getApplicationContext(), "Why would you want to exit such a great app?", Toast.LENGTH_LONG).show();
        }
        else if (v.equals(buttonBegin)) {
            Intent intent = new Intent (this, question.class);
            startActivity(intent);
        }
    }

}

Here is the code for both of my buttons from my XML file:

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Begin"
    android:id="@+id/begin"
    android:layout_marginTop="45dp"
    android:layout_below="@+id/textView"
    android:layout_alignRight="@+id/textView"
    android:layout_alignEnd="@+id/textView"
    android:clickable="true"
    android:background="#ffffff"/>

<Button
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Exit"
    android:id="@+id/exit"
    android:layout_marginTop="27dp"
    android:layout_below="@+id/begin"
    android:layout_alignLeft="@+id/begin"
    android:layout_alignStart="@+id/begin"
    android:clickable="true"
    android:background="#ffffff" />

Here is my stacktrace message:

7-2477/? E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.noot_a_normal_pc.kmtomiles, PID: 2477
android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.noot_a_normal_pc.kmtomiles/com.example.noot_a_normal_pc.kmtomiles.question}; have you declared this activity in your AndroidManifest.xml?
 at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1794)
 at android.app.Instrumentation.execStartActivity(Instrumentation.java:1512)
 at android.app.Activity.startActivityForResult(Activity.java:3917)
 at android.app.Activity.startActivityForResult(Activity.java:3877)
 at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:842)
 at android.app.Activity.startActivity(Activity.java:4200)
 at android.app.Activity.startActivity(Activity.java:4168)
 at com.example.noot_a_normal_pc.kmtomiles.MainActivity.onClick(MainActivity.java:33)
 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)

http://stackoverflow.com/questions/23353173/unfortunately-myapp-has-stopped-how-can-i-solve-this — Mike M., Apr 10 '17 at 00:58
*"the app crashes with no error message"* no, there is an error message. Check the stacktrace and post it here — codeMagic, Apr 10 '17 at 01:03
there is a error message, also question.class, is that a actual class, why are not following convention should be upper case Question.class — Remario, Apr 10 '17 at 01:14
Someone correct me if I am wrong, but I don't think you should be using `equals()` to compare a view, rather you should be using `==`. http://stackoverflow.com/questions/7520432/what-is-the-difference-between-vs-equals-in-java — sam_c, Apr 10 '17 at 01:15
No you are wrong, views are objects, not primitive, so only equals can be used. — Remario, Apr 10 '17 at 01:18
make sure the question class is an Activity (or service、receiver) and registered in your AndroidManifest. By the way, you'd better use v.getId() == R.id.begin ( or use switch case) instead of equals. — jiashie, Apr 10 '17 at 01:28

Remario · Answer 1 · 2017-04-10T01:31:13.270

3

Scope of this keyword is rather specific, use getContext() or getBaseContext() instead.or MainActivity.this

You have not declared your activity in your manifest.That is why you are getting the error. For example <activity android:name="YourActivityName" />

Also the way you are comparing possibility of a view is not exactly right, instead use a switch statement with v.getId() method then each case statement with their id property. case R.id.view_name.

edited Apr 10 '17 at 01:31

answered Apr 10 '17 at 01:16

Remario

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you need to add your activity to the manifest to let it know it exist. – Remario Apr 10 '17 at 01:20
Also rename your class to Question instead convention over type. – Remario Apr 10 '17 at 01:26
also the error is pretty clear ,android.content.ActivityNotFoundException: Unable to find explicit activity class – Remario Apr 10 '17 at 01:47

score 0 · Answer 2 · answered Apr 10 '17 at 02:28

As a programmer, you need to read and understand the error log given (when app crashed).

By having logcat, at line

android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.noot_a_normal_pc.kmtomiles/com.example.noot_a_normal_pc.kmtomiles.question}; have you declared this activity in your AndroidManifest.xml?

It is said that you have not declared your activity in manifest. The easiest way to create an activity without declare in manifest is by click

File > New > Activity > Empty Activity

Android Studio will create both Java and XML file (layout), and of course it will declare your activity in Manifests.XML too.

Perhaps my answer will help you in future :)

Intent button in Android Studio crashes the app

2 Answers2