Simple android app crashes on startup

Question

I am creating a new Android app, but it crashes on startup (phone and emulator).

Here is the code:

Arcig Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.tona.arcig"
    android:versionCode="1"
    android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="15"
    android:targetSdkVersion="17" /><application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme">
    <activity android:name="MainActivity" android:label="@string/app_name">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

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

Strings.xml

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

    <string name="suplovani">Suplování</string>
    <string name="rozvrh">Rozvrh hodin</string>
    <string name="prihlasovani">Přihlašování do systému</string>
    <string name="email">Email</string>
    <string name="moodle">Moodle</string>
    <string name="kdm">KDM</string>
    <string name="o_aplikaci">O Aplikaci</string>
    <string name="app_name">Arcig.CZ</string>

</resources>

activity_main.xml

    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >

        <ImageButton
            android:id="@+id/imageButton1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:contentDescription="@string/suplovani"
            android:src="@drawable/suplovani" />

        <ImageButton
            android:id="@+id/imageButton2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:contentDescription="@string/rozvrh"
            android:src="@drawable/rozvrh" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <ImageButton
            android:id="@+id/imageButton3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:contentDescription="@string/prihlasovani"
            android:src="@drawable/prihlasovani" />

        <ImageButton
            android:id="@+id/imageButton4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:contentDescription="@string/email"
            android:src="@drawable/email" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <ImageButton
            android:id="@+id/imageButton5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:contentDescription="@string/email"
            android:src="@drawable/moodle" />

        <ImageButton
            android:id="@+id/imageButton6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_weight="2"
            android:contentDescription="@string/kdm"
            android:src="@drawable/jidelna" />

    </LinearLayout>

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="vertical" >

        <ImageButton
            android:id="@+id/imageButton7"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:contentDescription="@string/o_aplikaci"
            android:src="@drawable/about" />

    </LinearLayout>

</LinearLayout>

MainActivity.java

package com.tona.arcig;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity {

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

        addListenerOnButton();
    }

    public void addListenerOnButton() {

        Button button = (Button) findViewById(R.id.imageButton1);
        button.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Do something in response to button click
                Toast.makeText(getApplicationContext(), "Mam rad vlaky", Toast.LENGTH_LONG).show();
            }
        });
    }
}

CONSOLE

[2014-09-07 16:39:21 - Arcig] ------------------------------
[2014-09-07 16:39:21 - Arcig] Android Launch!
[2014-09-07 16:39:21 - Arcig] adb is running normally.
[2014-09-07 16:39:21 - Arcig] Performing com.tona.arcig.MainActivity activity launch
[2014-09-07 16:39:21 - Arcig] Automatic Target Mode: Unable to detect device compatibility. Please select a target device.
[2014-09-07 16:39:23 - Arcig] Application already deployed. No need to reinstall.
[2014-09-07 16:39:23 - Arcig] Starting activity com.tona.arcig.MainActivity on device 0123456789ABCDEFG
[2014-09-07 16:39:24 - Arcig] ActivityManager: Starting: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] cmp=com.tona.arcig/.MainActivity }

When I execute the app, it just shows a crash message. :( Can anybody help me? Have I made any mistakes in the code? Thanks a lot guys

Answer 1

<ImageButton
        android:id="@+id/imageButton1"

and

Button button = (Button) findViewById(R.id.imageButton1);

ImageButton is not a Button so this causes ClassCastException you would have seen in your logcat if you had included it in the question. (Hint: Always start crash-solving with the stacktrace in logcat.)

Change the latter part to

ImageButton button = (ImageButton) findViewById(R.id.imageButton1);

Answer 2

I can see you are using ImageButton. I guess, the drawable images source size are more. If the images size are more android app will crash. Please try to keep your individual image size as low as possible. May be with in 50-60KB per image.