FATAL EXCEPTION: main java.lang.RuntimeException: Etkinlik başlatılamıyor ComponentInfo()

Question

Bu sorunu yaşıyorum ve this cevabını izledim ancak sorunumu çözemedim. Sanırım sadece aynı.

Activity sayfasında iki farklı sekme oluşturmak istedim, ancak çalışmadığı ortaya çıktı.

Kodda neyin yanlış olduğundan emin değilim.

MainActivity.java

package pasirgudangcouncilstate.infocenter; 

import android.graphics.Color; 
import android.os.Bundle; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v4.view.PagerTabStrip; 
import android.support.v4.view.ViewPager; 
import android.view.View; 
import android.support.design.widget.NavigationView; 
import android.support.v4.view.GravityCompat; 
import android.support.v4.widget.DrawerLayout; 
import android.support.v7.app.ActionBarDrawerToggle; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.Menu; 
import android.view.MenuItem; 



public class MainActivity extends AppCompatActivity 
     implements NavigationView.OnNavigationItemSelectedListener { 


    NavigationView navigationView = null; 
    Toolbar toolbar = null; 

    ViewPager pager; 
    PagerTabStrip tab_strp; 

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

     ActivityFragment mapager = new ActivityFragment(getSupportFragmentManager()); 

     pager = (ViewPager)findViewById(R.id.pager); 
     pager.setAdapter(mapager); 
     tab_strp=(PagerTabStrip)findViewById(R.id.tab_strip); 
     tab_strp.setTextColor(Color.WHITE); 

     //  Set Fragment Initially 
     UtamaFragment fragment = new UtamaFragment(); 
     android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
     fragmentTransaction.replace(R.id.fragment_container, fragment); 
     fragmentTransaction.commit(); 

     toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 

     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
      @Override 
      public void onClick(View view) { 
       Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
         .setAction("Action", null).show(); 
      } 
     }); 

     DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
     ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
       this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close); 
     drawer.addDrawerListener(toggle); 
     toggle.syncState(); 

     navigationView = (NavigationView) findViewById(R.id.nav_view); 
     navigationView.setNavigationItemSelectedListener(this); 
    } 

    @Override 
    public void onBackPressed() { 
     DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
     if (drawer.isDrawerOpen(GravityCompat.START)) { 
      drawer.closeDrawer(GravityCompat.START); 
     } else { 
      super.onBackPressed(); 
     } 
    } 



    @Override 
    public boolean onOptionsItemSelected(MenuItem item) { 
     // Handle action bar item clicks here. The action bar will 
     // automatically handle clicks on the Home/Up button, so long 
     // as you specify a parent activity in AndroidManifest.xml. 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    @SuppressWarnings("StatementWithEmptyBody") 
    @Override 
    public boolean onNavigationItemSelected(MenuItem item) { 
     // Handle navigation view item clicks here. 
     int id = item.getItemId(); 

     if (id == R.id.nav_home) { 

      //  Set Fragment Initially 
      UtamaFragment fragment = new UtamaFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 
      // Handle the camera action 
     } else if (id == R.id.nav_background) { 

      //  Set Fragment Initially 
      LatarBelakangFragment fragment = new LatarBelakangFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 

     } else if (id == R.id.nav_services) { 

      //  Set Fragment Initially 
      PerkhidmatanFragment fragment = new PerkhidmatanFragment(); 
      android.support.v4.app.FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction(); 
      fragmentTransaction.replace(R.id.fragment_container, fragment); 
      fragmentTransaction.commit(); 

     } else if (id == R.id.nav_activity) { 

      ActivityFragment mapager = new ActivityFragment(getSupportFragmentManager()); 
      pager = (ViewPager)findViewById(R.id.pager); 

      pager.setAdapter(mapager); 
      tab_strp=(PagerTabStrip)findViewById(R.id.tab_strip); 
      tab_strp.setTextColor(Color.WHITE); 

     } else if (id == R.id.nav_contact) { 

     } 

     DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout); 
     drawer.closeDrawer(GravityCompat.START); 
     return true; 
    } 
} 

03-26 05:57:16.932 2158-2158/pasirgudangcouncilstate.infocenter I/art: Not late-enabling -Xcheck:jni (already on) 
    03-26 05:57:17.095 2158-2158/pasirgudangcouncilstate.infocenter W/System: ClassLoader referenced unknown path: /data/app/pasirgudangcouncilstate.infocenter-2/lib/x86 
    03-26 05:57:17.598 2158-2158/pasirgudangcouncilstate.infocenter D/AndroidRuntime: Shutting down VM 
    03-26 05:57:17.598 2158-2158/pasirgudangcouncilstate.infocenter E/AndroidRuntime: FATAL EXCEPTION: main 
Process: pasirgudangcouncilstate.infocenter, PID: 2158 
java.lang.RuntimeException: Unable to start activity ComponentInfo{pasirgudangcouncilstate.infocenter/pasirgudangcouncilstate.infocenter.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.support.v4.view.PagerTabStrip.setTextColor(int)' 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.support.v4.view.PagerTabStrip.setTextColor(int)' on a null object reference 
at pasirgudangcouncilstate.infocenter.MainActivity.onCreate(MainActivity.java:41) 
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)  
    03-26 05:57:21.767 2158-2160/pasirgudangcouncilstate.infocenter W/art: Suspending all threads took: 7.989ms 
    03-26 05:57:24.039 2158-2160/pasirgudangcouncilstate.infocenter W/art: Suspending all threads took: 35.938ms 
    03-26 05:57:28.562 2158-2158/? I/Process: Sending signal. PID: 2158 SIG: 9 

Answer 1

çıkarın activity_main.xml

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

<android.support.v4.widget.DrawerLayout 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:id="@+id/drawer_layout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent" 
    android:fitsSystemWindows="true" 
    tools:openDrawer="start"> 

    <include 
     layout="@layout/app_bar_main" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" /> 

    <android.support.design.widget.NavigationView 
     android:id="@+id/nav_view" 
     android:layout_width="wrap_content" 
     android:layout_height="match_parent" 
     android:layout_gravity="start" 
     android:fitsSystemWindows="true" 
     app:headerLayout="@layout/nav_header_main" 
     app:menu="@menu/activity_main_drawer" /> 

    <android.support.v4.view.ViewPager 
     android:id="@+id/pager" 
     android:layout_width="match_parent" 
     android:layout_height="0dp" 
     android:layout_weight="1" /> 

</android.support.v4.widget.DrawerLayout> 

Logcat yo ur kodu ve bunu doğrudan ekle. ve bu satırı da Aktivite kodunuzda kaldırın. Her şeyden

tab_strp.setTextColor(Color.WHITE); 

Answer 2

Birincisi, yerine PagerTabStrip ait TabLayout kullanarak öneriyoruz.

İkinci olarak, xml'inizde PagerTabStrip'u göremiyorum, bu yüzden NullPointerException'u alıyorsunuz. Bunu kaldırın ve ViewPager'u onsuz çalışmayı deneyin ve daha sonra sadece this eğitimini takip ederek ekleyin. Burada logcat