My program runs, but when I click the q button it should open a new activity, the program closes saying that it hears an error.
FATAL EXCEPTION: main Process: com.example.raissa.calencon, PID: 2142
java.lang.RuntimeException: Unable to start activity ComponentInfo {com.example.raissa.calencon / com.example.raissa.calencon.CriarEvent}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled (boolean) 'on a null object reference
at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2416) at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:2476) at android.app.ActivityThread.-wrap11 (ActivityThread.java)
at android.app.ActivityThread $ H.handleMessage (ActivityThread.java:1344)
at android.os.Handler.dispatchMessage (Handler.java:102)
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)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled (boolean)' on a null object reference
at com.example.raissa.calencon.CriarEvento.onCreate (BuildEvent.java:12) at android.app.Activity.performCreate (Activity.java:6237)
at android.app.Instrumentation.callActivityOnCreate (Instrumentation.java:1107) at android.app.ActivityThread.performLaunchActivity (ActivityThread.java:2369) at android.app.ActivityThread.handleLaunchActivity (ActivityThread.java:2476) at android.app.ActivityThread.-wrap11 (ActivityThread.java)
at android.app.ActivityThread $ H.handleMessage (ActivityThread.java:1344) at android.os.Handler.dispatchMessage (Handler.java:102)
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)
What can it be? My code:
import android.content.Intent;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ListView;
import com.google.android.gms.appindexing.Action;
import com.google.android.gms.appindexing.AppIndex;
import com.google.android.gms.common.api.GoogleApiClient;
import java.util.ArrayList;
public class MainActivity extends AppCompatActivity {
/**
* ATTENTION: This was auto-generated to implement the App Indexing API.
* See https://g.co/AppIndexing/AndroidStudio for more information.
*/
private GoogleApiClient client;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ArrayList<evento_onClick> lista = new ArrayList<evento_onClick>();
evento_onClick a = new evento_onClick("item a", R.drawable.fireworks, "22/03");
evento_onClick b = new evento_onClick("item b", R.drawable.fireworks, "22/03");
evento_onClick c = new evento_onClick("item c", R.drawable.fireworks, "22/03");
evento_onClick d = new evento_onClick("item d", R.drawable.fireworks, "22/03");
evento_onClick e = new evento_onClick("item e", R.drawable.fireworks, "22/03");
evento_onClick f = new evento_onClick("item f", R.drawable.fireworks, "22/03");
evento_onClick g = new evento_onClick("item g", R.drawable.fireworks, "22/03");
evento_onClick h = new evento_onClick("item h", R.drawable.fireworks, "22/03");
lista.add(a);
lista.add(b);
lista.add(c);
lista.add(d);
lista.add(e);
lista.add(f);
lista.add(g);
lista.add(h);
ListaAdapterEvento AdapterEvento = new ListaAdapterEvento(this, lista);
ListView listView = (ListView) findViewById(R.id.listView);
listView.setAdapter(AdapterEvento);
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}
public void acionaBotao(View view) {
Intent novoEvento = new Intent(this, CriarEvento.class);
startActivity(novoEvento);
}
@Override
public void onStart() {
super.onStart();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
client.connect();
Action viewAction = Action.newAction(
Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
// Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://com.example.raissa.calencon/http/host/path")
);
AppIndex.AppIndexApi.start(client, viewAction);
}
@Override
public void onStop() {
super.onStop();
// ATTENTION: This was auto-generated to implement the App Indexing API.
// See https://g.co/AppIndexing/AndroidStudio for more information.
Action viewAction = Action.newAction(
Action.TYPE_VIEW, // TODO: choose an action type.
"Main Page", // TODO: Define a title for the content shown.
// TODO: If you have web page content that matches this app activity's content,
// make sure this auto-generated web page URL is correct.
// Otherwise, set the URL to null.
Uri.parse("http://host/path"),
// TODO: Make sure this auto-generated app deep link URI is correct.
Uri.parse("android-app://com.example.raissa.calencon/http/host/path")
);
AppIndex.AppIndexApi.end(client, viewAction);
client.disconnect();
} }
XML file:
<Button
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/mais"
android:id="@+id/button"
android:textSize="25sp"
android:layout_alignParentTop="true"
android:layout_alignRight="@+id/listView"
android:layout_alignEnd="@+id/listView"
android:layout_alignParentEnd="false"
android:background="#3ed2cb"
android:textAlignment="center"
android:nestedScrollingEnabled="false"
android:onClick="acionaBotao" />
I have tried some internet tutorials and some answers from other posts here but they did not work. When I start the program:
W / EGL_emulation: eglSurfaceAttrib not implemented 01-07 18: 45: 54,989 2071-2086 / com.example.raissa.calencon W / OpenGLRenderer: Failed to set EGL_SWAP_BEHAVIOR on surface 0xeae349c0, error = EGL_SUCCESS