Fehler in der Navigationsleiste

Question

Ich habe versucht, eine App im Android Studio auszuführen, aber ich bekomme immer wieder diesen seltsamen Fehler.

Ich konnte kaum verstehen, worum es bei diesem Fehler geht und wie man das beheben kann, Ihre Hilfe wäre sehr willkommen.

hier ist die logcat

06-16 15:26:02.141 5270-5270/com.sensiblewallet E/AndroidRuntime: FATAL EXCEPTION: main 
Process: com.sensiblewallet, PID: 5270 
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sensiblewallet/com.sensiblewallet.ActivityMainWallet}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2452) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512) 
    at android.app.ActivityThread.-wrap11(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1376) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:148) 
    at android.app.ActivityThread.main(ActivityThread.java:5481) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618) 
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference 
    at com.sensiblewallet.ActivityMainWallet.onCreate(ActivityMainWallet.java:212) 
    at android.app.Activity.performCreate(Activity.java:6251) 
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1107) 
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2405) 
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)  
    at android.app.ActivityThread.-wrap11(ActivityThread.java)  
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1376)  
    at android.os.Handler.dispatchMessage(Handler.java:102)  
    at android.os.Looper.loop(Looper.java:148)  
    at android.app.ActivityThread.main(ActivityThread.java:5481)  
    at java.lang.reflect.Method.invoke(Native Method)  
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728)  
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)  

hier ist das Stück Code, es anzeigt.

mDrawerLayout = (DrawerLayout)findViewById(R.id.drawer_layout); 
mDrawerLayout.setDrawerShadow(R.drawable.drawer_shadow, GravityCompat.END); 
mDrawerLay = (NavigationView)findViewById(R.id.navigation_view); 
mDrawerLay.setNavigationItemSelectedListener(this); 
TextView navigationTotalCreditTextView = (TextView)mDrawerLay.findViewById(R.id.nav_drawer_total_credits); 
navigationTotalCreditTextView.setText("Total Credits: " + PreferenceConnector.readInteger(aiContext, 
     PreferenceConnector.WALLETPOINTS, 0)); 
TextView navigationWalletIDText = (TextView)mDrawerLay.findViewById(R.id.nav_drawer_wallet_id); 
navigationWalletIDText.setText("Wallet ID: " + PreferenceConnector.readString(aiContext, 
     PreferenceConnector.WALLETID, "")); 
TextView navigationUsernameText = (TextView)mDrawerLay.findViewById(R.id.nav_drawer_username); 
navigationUsernameText.setText(PreferenceConnector.readString(aiContext, 
     PreferenceConnector.USERNAME, "")); 
// MyUtils.setFontAllView((RelativeLayout)findViewById(R.id.laymenu)); 

Answer 1

Versuchen Sie diesen Code:

View v = mDrawerLay.getHeaderView(0); 
    TextView navigationTotalCreditTextView = (TextView)v.findViewById(R.id.nav_drawer_total_credits); 
    TextView navigationWalletIDText = (TextView)v.findViewById(R.id.nav_drawer_wallet_id); 
navigationWalletIDText.setText("Wallet ID: " + PreferenceConnector.readString(aiContext, 
     PreferenceConnector.WALLETID, "")); 
    TextView navigationUsernameText = (TextView)v .findViewById(R.id.nav_drawer_username); 
navigationUsernameText.setText(PreferenceConnector.readString(aiContext, 
     PreferenceConnector.USERNAME, ""));