I can't understand why my app crashes when I try to change Activity
.
Here is 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 is the MainActivity
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);
}
}
SecondActivity
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){}
}
activity_main.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_activity_layout.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>
switchTo1(View view)
has a private
access modifier and cannot be accesed outside of the class. Make it public
:
public void switchTo1(View view)