A layout manager for the RecyclerView with interchangeable linear, grid, and staggered displays of views, all with configurable section headers including the sticky variety as specified in the material design docs.
01-22 01:23:35.234 25771-25771/com.example.dell_user.wechat E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.dell_user.wechat, PID: 25771
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dell_user.wechat/com.example.dell_user.wechat.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2703)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2774)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1588)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5955)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:930)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:791)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference
at com.example.dell_user.wechat.MainActivity.initLineImage(MainActivity.java:93)
at com.example.dell_user.wechat.MainActivity.onCreate(MainActivity.java:40)
at android.app.Activity.performCreate(Activity.java:6378)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1124)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2656)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2774)
at android.app.ActivityThread.-wrap11(ActivityThread.java)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1588)
at android.os.Handler.dispatchMessage(Handler.java:111)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:5955)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:930)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:791)
01-22 01:23:35.234 25771-25771/com.example.dell_user.wechat E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.dell_user.wechat, PID: 25771 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.dell_user.wechat/com.example.dell_user.wechat.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2703) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2774) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1588) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loop(Looper.java:207) at android.app.ActivityThread.main(ActivityThread.java:5955) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:930) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:791) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.ViewGroup$LayoutParams android.widget.ImageView.getLayoutParams()' on a null object reference at com.example.dell_user.wechat.MainActivity.initLineImage(MainActivity.java:93) at com.example.dell_user.wechat.MainActivity.onCreate(MainActivity.java:40) at android.app.Activity.performCreate(Activity.java:6378) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1124) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2656) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2774) at android.app.ActivityThread.-wrap11(ActivityThread.java) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1588) at android.os.Handler.dispatchMessage(Handler.java:111) at android.os.Looper.loop(Looper.java:207) at android.app.ActivityThread.main(ActivityThread.java:5955) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:930) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:791)
just check check ..