Mattia Rubini Mattia Rubini - 2 months ago 6
Java Question

Android activity crashing when launched

So here the code of my app (I'm a real beginner in android), I can't understand why my app crashes when I try to change activity...
I've been digging A lot in the internet, but can't find a solution...

Here the manifest file:

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.android.testsubject">

<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>
<activity android:name=".SecondActivity"/>
</application>




Here the first java file:

package com.example.android.testsubject;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends AppCompatActivity {

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

private void switchTo1(View view){
Intent intentTo2 = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intentTo2);
}
}


Second java File:

package com.example.android.testsubject;

import android.os.Bundle;
import android.view.View;

public class SecondActivity extends MainActivity {

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

public void switchTo2(View view){}

}


First xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:orientation="vertical"
android:gravity="center_horizontal"
tools:context="com.example.android.testsubject.MainActivity">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="This, is screen 1"
android:layout_marginBottom="16sp" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Here we go to the second screen"
android:onClick="switchTo1" />

</LinearLayout>


Second xml file:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="16sp"
android:gravity="center_horizontal"
android:background="#FFFF00">

<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="This, is screen 2"
android:layout_marginBottom="16sp" />

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Here we go to the first screen"
android:onClick="switchTo2" />

</LinearLayout>


Thanks in advance for any help!!

EDIT:
I am a moron....
As someone pointed out

private void switchTo1(View view){
Intent intentTo2 = new Intent(MainActivity.this, SecondActivity.class);
startActivity(intentTo2);
}


is a private function...

Answer

switchTo1(View view) has a private access modifier and cannot be accesed outside of the class. Make it public:

public void switchTo1(View view)