導航頭部初始化變量的空指針異常

爲什麼我會在設置來自共享首選項的值時在我的NavigationView頭部初始化變量時得到空指針異常？導航頭部初始化變量的空指針異常

這裏是我的代碼

private void setNavigationHeader() { 
    View navHeader = mNavigationView.getHeaderView(0); 

    TextView mProfileName = (TextView) navHeader.findViewById(R.id.profile_name); 
    TextView mProfileEmail = (TextView) navHeader.findViewById(R.id.profile_email); 

    User user = Utils.getCurrentUser(MainActivity.this); 

119 mProfileName.setText(user.getName()); 
    mProfileEmail.setText(user.getEmail()); 
}

記錄錯誤

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.myapp.userapp/com.myapp.userapp.MainActivity}: java.lang.NullPointerException 
                    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184) 
                    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233) 
                    at android.app.ActivityThread.access$800(ActivityThread.java:135) 
                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196) 
                    at android.os.Handler.dispatchMessage(Handler.java:102) 
                    at android.os.Looper.loop(Looper.java:136) 
                    at android.app.ActivityThread.main(ActivityThread.java:5001) 
                    at java.lang.reflect.Method.invokeNative(Native Method) 
                    at java.lang.reflect.Method.invoke(Method.java:515) 
                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785) 
                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601) 
                    at dalvik.system.NativeStart.main(Native Method) 
                    Caused by: java.lang.NullPointerException 
                    at com.myapp.userapp.MainActivity.setNavigationHeader(MainActivity.java:119) 
                    at com.myapp.userapp.MainActivity.onCreate(MainActivity.java:97) 
                    at android.app.Activity.performCreate(Activity.java:5231) 
                    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087) 
                    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148) 
                    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2233)  
                    at android.app.ActivityThread.access$800(ActivityThread.java:135)  
                    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)  
                    at android.os.Handler.dispatchMessage(Handler.java:102)  
                    at android.os.Looper.loop(Looper.java:136)  
                    at android.app.ActivityThread.main(ActivityThread.java:5001)  
                    at java.lang.reflect.Method.invokeNative(Native Method)  
                    at java.lang.reflect.Method.invoke(Method.java:515)  
                    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)  
                    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)  
                    at dalvik.system.NativeStart.main(Native Method)

來源

2016-05-11 Geob

發佈您的佈局xml。此外，什麼是MainActivity.java – jaibatrik

線119檢查此http://stackoverflow.com/a/34766504/2032561 – Bharatesh

嘗試增加headerView到navigationView這樣的：

LinearLayout navHeader=(LinearLayout) LayoutInflater.from(this).inflate(R.layout.drawer_header, null); 
navigationView.addHeaderView(linearLayout); 

TextView mProfileName = (TextView) navHeader.findViewById(R.id.profile_name); 
TextView mProfileEmail = (TextView) navHeader.findViewById(R.id.profile_email);

來源

2016-05-11 13:06:14

充氣佈局和navigationView

LinearLayout navHeader=(LinearLayout) LayoutInflater.from(this).inflate(R.layout.drawer_header, null); 
navigationView.addHeaderView(linearLayout); 

TextView mProfileName = (TextView) navHeader.findViewById(R.id.profile_name); 
TextView mProfileEmail = (TextView) navHeader.findViewById(R.id.profile_email); 
mProfileName.setText(user.getName()); 
mProfileEmail.setText(user.getEmail());

來源

2016-05-11 13:13:13

導航頭部初始化變量的空指針異常

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