My application a few moments after launching. Initially, the app used to run without problems, but after i added a login screen before the main screen, it frequently stops, with an error "Unfortunately AutoparesOnline has stopped. I'm new to android and i'd appreciate any help. below is the log, the activity.xml and the java code.
This is the xml.
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:theme="@style/newTheme"
android:layout_weight="6"
android:background="@android:color/black">
<LinearLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginLeft="7dp"
android:layout_marginStart="7dp">
<TextView
android:text="@string/welcome"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="@+id/tv_welcome"
android:textStyle="normal|bold"
android:textColor="@color/btn_login_bg"
android:textSize="24sp"
android:textAlignment="center" />
</LinearLayout>
<RelativeLayout
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:weightSum="1"
android:background="@drawable/circle"
android:layout_centerVertical="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true">
<ImageView
android:contentDescription="A mechanic with his tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:src="@drawable/handy_man"
android:id="@+id/imageView9"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="19dp"
tools:ignore="HardcodedText" />
</RelativeLayout>
<Button
android:text="@string/Continue"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="@+id/btnStartAnotherActivity"
style="@style/Widget.AppCompat.Button.Colored"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"/>
</RelativeLayout>
This is the java code
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.widget.Button;
import android.widget.ProgressBar;
public class MainActivity extends AppCompatActivity{
Button btn1;
private ProgressBar pBar;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_first);
btn1 = (Button) findViewById(R.id.btnStartMainActivity);
btn1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
Intent intent = new Intent(MainActivity.this, AnotherActivity.class);
startActivity(intent);
}
});
pBar.setVisibility(View.VISIBLE);
}
Here is part of the error.
FATAL EXCEPTION: main
Process: co.autosparesonline.ke, PID: 3011
java.lang.RuntimeException: Unable to start activity ComponentInfo{co.autosparesonline.ke/co.autosparesonline.ke.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
at co.autosparesonline.ke.MainActivity.onCreate(MainActivity.java:21)
at android.app.Activity.performCreate(Activity.java:6662)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2599)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
at android.app.ActivityThread.-wrap12(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
