1. 首页
  2. 问答
  3. Android如何避免NullPointException

Android如何避免NullPointException

2013-03-05 89 views
0

我在我的代码中有NullPointException，这就是为什么我的应用程序崩溃的原因... 我是Android开发新手，你能帮我避免这个Null异常吗？Android如何避免NullPointException

这里是一些代码，在那里我觉得是这样的错误：

@Override 
public void onClick(View v) { 
    btn_skip = (Button) findViewById(R.id.btn_skip); 
    // get data 
    String email_txt = email.getEditableText().toString(); 
    String confirme_email = confirm_email.getEditableText().toString(); 

    //get IMEI 
    TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE); 
    imei = telephonyManager.getDeviceId(); 

    if (v == btn_skip) 
    { 
     sendPostRequest(null, null, imei); 
    } 
    //if email is not valid then show errors 
    else if (!checkEmail(email.getText().toString()) && v == btn_get_access) 
    { 
     email_error.setVisibility(View.VISIBLE); 
     email.requestFocus(); 
     //Toast.makeText(getBaseContext(), "lkdjfgkdjg", Toast.LENGTH_LONG).show(); 
    } 
    //else if (!confirme_email.equals(email_txt) && v == btn_get_access) 
    else if (!email_txt.equals(confirme_email)) 
    { 
     email_confirm_error.setVisibility(View.VISIBLE); 
     confirm_email.requestFocus(); 
    } 
    else 
    { 
     email_error.setVisibility(View.GONE); 
     email_confirm_error.setVisibility(View.GONE); 
     sendPostRequest(email_txt, confirme_email, imei); 
    } 
}

，所以我怎么得到这个错误： 在我的应用我有2个活动，我可以通过按钮切换它们，第一个按钮发送我从服务器上的用户获得的一些数据（所有输入都填充了数据），第二个按钮我可以跳过输入填充并进入第二个屏幕（所有输入都是空的）。 从第二个屏幕我可以回到没有任何数据的第一个屏幕（当我按下这个后退按钮，我有这个空例外）。 请帮我这个错误，因为我无法想象如何避免它...

UPD logcat的

03-05 10:01:07.214: W/ActivityThread(12011): Application com.vladimir.expert_suise is  waiting for the debugger on port 8100... 
03-05 10:01:07.224: I/System.out(12011): Sending WAIT chunk 
03-05 10:01:07.224: I/dalvikvm(12011): Debugger is active 
03-05 10:01:07.424: I/System.out(12011): Debugger has connected 
03-05 10:01:07.424: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:07.624: I/System.out(12011): waiting for debugger to settle... 

03-05 10:01:07.814: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:08.014: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:08.215: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:08.415: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:08.615: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:08.815: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:09.015: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:09.226: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:09.426: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:09.626: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:09.826: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:10.026: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:10.226: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:10.427: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:10.627: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:10.827: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:11.027: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:11.227: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:11.428: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:11.628: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:11.828: I/System.out(12011): waiting for debugger to settle... 
03-05 10:01:12.028: I/System.out(12011): debugger has settled (1463) 
03-05 10:01:13.620: D/libEGL(12011): loaded /system/lib/egl/libGLES_android.so 
03-05 10:01:13.800: D/libEGL(12011): loaded /system/lib/egl/libEGL_adreno200.so 
03-05 10:01:14.080: D/libEGL(12011): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 
03-05 10:01:14.080: D/libEGL(12011): loaded /system/lib/egl/libGLESv2_adreno200.so 
03-05 10:01:14.401: I/Adreno200-EGLSUB(12011): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:14.561: D/memalloc(12011): ashmem: Mapped buffer base:0x520a0000 size:1536000 fd:61 
03-05 10:01:14.591: D/OpenGLRenderer(12011): Enabling debug mode 0 
03-05 10:01:15.141: D/OpenGLRenderer(12011): has fontRender patch 
03-05 10:01:15.171: D/OpenGLRenderer(12011): has fontRender patch 
03-05 10:01:15.211: D/OpenGLRenderer(12011): has fontRender patch 
03-05 10:01:15.281: D/memalloc(12011): ashmem: Mapped buffer base:0x5251a000 size:1536000 fd:64 
03-05 10:01:15.962: D/memalloc(12011): ashmem: Mapped buffer base:0x52691000 size:1536000 fd:67 
03-05 10:01:19.996: I/Adreno200-EGLSUB(12011): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:20.006: D/memalloc(12011): ashmem: Mapped buffer base:0x52b08000 size:1536000 fd:76 
03-05 10:01:20.316: D/memalloc(12011): ashmem: Mapped buffer base:0x52cff000 size:1536000 fd:79 
03-05 10:01:20.647: I/Adreno200-EGLSUB(12011): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:20.657: D/memalloc(12011): ashmem: Mapped buffer base:0x52f76000 size:1536000 fd:82 
03-05 10:01:20.797: D/memalloc(12011): ashmem: Mapped buffer base:0x530ed000 size:1536000 fd:88 
03-05 10:01:20.957: D/memalloc(12011): ashmem: Mapped buffer base:0x53264000 size:1536000 fd:91 
03-05 10:01:21.157: D/memalloc(12011): ashmem: Mapped buffer base:0x533db000 size:1536000 fd:94 
03-05 10:01:21.177: D/OpenGLRenderer(12011): Flushing caches (mode 0) 
03-05 10:01:21.207: D/OpenGLRenderer(12011): Flushing caches (mode 0) 
03-05 10:01:22.999: I/Adreno200-EGLSUB(12011): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:23.019: D/memalloc(12011): ashmem: Mapped buffer base:0x5251a000 size:1536000 fd:63 
03-05 10:01:23.309: D/memalloc(12011): ashmem: Mapped buffer base:0x52691000 size:1536000 fd:69 
03-05 10:01:23.419: I/Adreno200-EGLSUB(12011): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:23.429: D/memalloc(12011): ashmem: Mapped buffer base:0x52a08000 size:1536000 fd:79 
03-05 10:01:23.610: D/memalloc(12011): ashmem: Mapped buffer base:0x52cff000 size:1536000 fd:88 
03-05 10:01:23.660: D/memalloc(12011): ashmem: Mapped buffer base:0x530ed000 size:1536000 fd:97 
03-05 10:01:23.830: D/memalloc(12011): ashmem: Mapped buffer base:0x53552000 size:1536000 fd:100 
03-05 10:01:23.850: D/OpenGLRenderer(12011): Flushing caches (mode 0) 
03-05 10:01:23.870: D/OpenGLRenderer(12011): Flushing caches (mode 0) 
03-05 10:01:25.291: I/Adreno200-EGLSUB(12011): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:25.301: D/memalloc(12011): ashmem: Mapped buffer base:0x5261a000 size:1536000 fd:63 
03-05 10:01:25.451: D/memalloc(12011): ashmem: Mapped buffer base:0x52e76000 size:1536000 fd:82 
03-05 10:01:25.481: D/OpenGLRenderer(12011): Flushing caches (mode 0) 
03-05 10:01:25.882: D/memalloc(12011): ashmem: Mapped buffer base:0x52a08000 size:1536000 fd:79 
03-05 10:01:27.603: D/AndroidRuntime(12011): Shutting down VM 
03-05 10:01:27.603: W/dalvikvm(12011): threadid=1: thread exiting with uncaught exception (group=0x40ad9228) 
03-05 10:01:27.633: E/AndroidRuntime(12011): FATAL EXCEPTION: main 
03-05 10:01:27.633: E/AndroidRuntime(12011): java.lang.NullPointerException 
03-05 10:01:27.633: E/AndroidRuntime(12011): at com.vladimir.expert_suise.FirstScreen.onClick(FirstScreen.java:174) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at android.view.View.performClick(View.java:3549) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at android.view.View$PerformClick.run(View.java:14400) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at android.os.Handler.handleCallback(Handler.java:605) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at android.os.Handler.dispatchMessage(Handler.java:92) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at android.os.Looper.loop(Looper.java:154) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at android.app.ActivityThread.main(ActivityThread.java:4945) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at java.lang.reflect.Method.invokeNative(Native Method) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at java.lang.reflect.Method.invoke(Method.java:511) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
03-05 10:01:27.633: E/AndroidRuntime(12011): at dalvik.system.NativeStart.main(Native Method) 
03-05 10:01:30.747: D/Process(12011): killProcess, pid=12011 
03-05 10:01:30.757: D/Process(12011): dalvik.system.VMStack.getThreadStackTrace(Native Method) 
03-05 10:01:30.757: D/Process(12011): java.lang.Thread.getStackTrace(Thread.java:599) 
03-05 10:01:30.757: D/Process(12011): android.os.Process.killProcess(Process.java:788) 
03-05 10:01:30.757: D/Process(12011): com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException(RuntimeInit.java:104) 
03-05 10:01:30.757: D/Process(12011): java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693) 
03-05 10:01:30.757: D/Process(12011): java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690) 
03-05 10:01:30.757: D/Process(12011): dalvik.system.NativeStart.main(Native Method) 
03-05 10:01:30.757: I/Process(12011): Sending signal. PID: 12011 SIG: 9 
03-05 10:01:31.307: D/libEGL(12216): loaded /system/lib/egl/libGLES_android.so 
03-05 10:01:31.307: D/libEGL(12216): loaded /system/lib/egl/libEGL_adreno200.so 
03-05 10:01:31.307: D/libEGL(12216): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 
03-05 10:01:31.317: D/libEGL(12216): loaded /system/lib/egl/libGLESv2_adreno200.so 
03-05 10:01:31.337: I/Adreno200-EGLSUB(12216): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:31.357: D/memalloc(12216): ashmem: Mapped buffer base:0x51fa0000 size:1536000 fd:61 
03-05 10:01:31.367: D/OpenGLRenderer(12216): Enabling debug mode 0 
03-05 10:01:31.417: D/OpenGLRenderer(12216): has fontRender patch 
03-05 10:01:31.437: D/OpenGLRenderer(12216): has fontRender patch 
03-05 10:01:31.467: D/OpenGLRenderer(12216): has fontRender patch 
03-05 10:01:31.507: D/memalloc(12216): ashmem: Mapped buffer base:0x5241a000 size:1536000 fd:64 
03-05 10:01:31.918: D/memalloc(12216): ashmem: Mapped buffer base:0x52691000 size:1536000 fd:67 
03-05 10:01:47.313: D/AndroidRuntime(12216): Shutting down VM 
03-05 10:01:47.313: W/dalvikvm(12216): threadid=1: thread exiting with uncaught exception (group=0x40ad9228) 
03-05 10:01:47.313: E/AndroidRuntime(12216): FATAL EXCEPTION: main 
03-05 10:01:47.313: E/AndroidRuntime(12216): java.lang.NullPointerException 
03-05 10:01:47.313: E/AndroidRuntime(12216): at com.vladimir.expert_suise.FirstScreen.onClick(FirstScreen.java:174) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at android.view.View.performClick(View.java:3549) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at android.view.View$PerformClick.run(View.java:14400) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at android.os.Handler.handleCallback(Handler.java:605) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at android.os.Handler.dispatchMessage(Handler.java:92) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at android.os.Looper.loop(Looper.java:154) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at android.app.ActivityThread.main(ActivityThread.java:4945) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at java.lang.reflect.Method.invokeNative(Native Method) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at java.lang.reflect.Method.invoke(Method.java:511) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
03-05 10:01:47.313: E/AndroidRuntime(12216): at dalvik.system.NativeStart.main(Native Method) 
03-05 10:01:49.064: D/Process(12216): killProcess, pid=12216 
03-05 10:01:49.064: D/Process(12216): dalvik.system.VMStack.getThreadStackTrace(Native Method) 
03-05 10:01:49.064: D/Process(12216): java.lang.Thread.getStackTrace(Thread.java:599) 
03-05 10:01:49.064: D/Process(12216): android.os.Process.killProcess(Process.java:788) 
03-05 10:01:49.064: D/Process(12216): com.android.internal.os.RuntimeInit$UncaughtHandler.uncaughtException(RuntimeInit.java:104) 
03-05 10:01:49.064: D/Process(12216): java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:693) 
03-05 10:01:49.064: D/Process(12216): java.lang.ThreadGroup.uncaughtException(ThreadGroup.java:690) 
03-05 10:01:49.064: D/Process(12216): dalvik.system.NativeStart.main(Native Method) 
03-05 10:01:49.064: I/Process(12216): Sending signal. PID: 12216 SIG: 9 
03-05 10:01:49.545: D/libEGL(12233): loaded /system/lib/egl/libGLES_android.so 
03-05 10:01:49.555: D/libEGL(12233): loaded /system/lib/egl/libEGL_adreno200.so 
03-05 10:01:49.555: D/libEGL(12233): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 
03-05 10:01:49.555: D/libEGL(12233): loaded /system/lib/egl/libGLESv2_adreno200.so 
03-05 10:01:49.575: I/Adreno200-EGLSUB(12233): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:01:49.585: D/memalloc(12233): ashmem: Mapped buffer base:0x51fb9000 size:1536000 fd:62 
03-05 10:01:49.585: D/OpenGLRenderer(12233): Enabling debug mode 0 
03-05 10:01:49.645: D/OpenGLRenderer(12233): has fontRender patch 
03-05 10:01:49.665: D/OpenGLRenderer(12233): has fontRender patch 
03-05 10:01:49.685: D/OpenGLRenderer(12233): has fontRender patch 
03-05 10:01:49.755: D/memalloc(12233): ashmem: Mapped buffer base:0x52466000 size:1536000 fd:65 
03-05 10:01:50.135: D/memalloc(12233): ashmem: Mapped buffer base:0x526dd000 size:1536000 fd:68 
03-05 10:01:51.347: D/OpenGLRenderer(12233): Flushing caches (mode 0) 
03-05 10:01:51.447: W/IInputConnectionWrapper(12233): showStatusIcon on inactive InputConnection 
03-05 10:01:51.447: W/IInputConnectionWrapper(12233): InputConnection = [email protected], active client = false 
03-05 10:01:51.647: D/OpenGLRenderer(12233): Flushing caches (mode 1) 
03-05 10:02:00.155: D/OpenGLRenderer(12233): Flushing caches (mode 1) 
03-05 10:02:08.814: D/OpenGLRenderer(12233): Flushing caches (mode 1) 
03-05 10:02:08.994: D/OpenGLRenderer(12233): Flushing caches (mode 2) 
03-05 10:02:32.427: W/ActivityThread(12468): Application com.vladimir.expert_suise is waiting for the debugger on port 8100... 
03-05 10:02:32.447: I/System.out(12468): Sending WAIT chunk 
03-05 10:02:32.447: I/dalvikvm(12468): Debugger is active 
03-05 10:02:32.647: I/System.out(12468): Debugger has connected 
03-05 10:02:32.647: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:32.847: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:33.047: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:33.247: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:33.448: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:33.648: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:33.848: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:34.048: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:34.248: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:34.449: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:34.649: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:34.859: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:35.049: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:35.249: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:35.450: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:35.650: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:35.850: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:36.050: I/System.out(12468): waiting for debugger to settle... 
03-05 10:02:36.250: I/System.out(12468): debugger has settled (1356) 
03-05 10:02:37.502: D/libEGL(12468): loaded /system/lib/egl/libGLES_android.so 
03-05 10:02:37.532: D/libEGL(12468): loaded /system/lib/egl/libEGL_adreno200.so 
03-05 10:02:37.582: D/libEGL(12468): loaded /system/lib/egl/libGLESv1_CM_adreno200.so 
03-05 10:02:37.582: D/libEGL(12468): loaded /system/lib/egl/libGLESv2_adreno200.so 
03-05 10:02:37.652: I/Adreno200-EGLSUB(12468): <ConfigWindowMatch:2078>: Format RGBA_8888. 
03-05 10:02:37.692: D/memalloc(12468): ashmem: Mapped buffer base:0x520a0000 size:1536000 fd:61 
03-05 10:02:37.702: D/OpenGLRenderer(12468): Enabling debug mode 0 
03-05 10:02:37.902: D/OpenGLRenderer(12468): has fontRender patch 
03-05 10:02:37.922: D/OpenGLRenderer(12468): has fontRender patch 
03-05 10:02:37.952: D/OpenGLRenderer(12468): has fontRender patch 
03-05 10:02:38.002: D/memalloc(12468): ashmem: Mapped buffer base:0x5251a000 size:1536000 fd:64 
03-05 10:02:38.312: D/memalloc(12468): ashmem: Mapped buffer base:0x52691000 size:1536000 fd:67 
03-05 10:03:07.731: D/dalvikvm(12468): Debugger has detached; object registry had 776 entries 
03-05 10:03:07.731: D/AndroidRuntime(12468): Shutting down VM 
03-05 10:03:07.731: W/dalvikvm(12468): threadid=1: thread exiting with uncaught exception (group=0x40ad9228) 
03-05 10:03:07.731: E/AndroidRuntime(12468): FATAL EXCEPTION: main 
03-05 10:03:07.731: E/AndroidRuntime(12468): java.lang.NullPointerException 
03-05 10:03:07.731: E/AndroidRuntime(12468): at com.vladimir.expert_suise.FirstScreen.onClick(FirstScreen.java:174) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at android.view.View.performClick(View.java:3549) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at android.view.View$PerformClick.run(View.java:14400) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at android.os.Handler.handleCallback(Handler.java:605) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at android.os.Handler.dispatchMessage(Handler.java:92) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at android.os.Looper.loop(Looper.java:154) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at android.app.ActivityThread.main(ActivityThread.java:4945) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at java.lang.reflect.Method.invokeNative(Native Method) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at java.lang.reflect.Method.invoke(Method.java:511) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551) 
03-05 10:03:07.731: E/AndroidRuntime(12468): at dalvik.system.NativeStart.main(Native Method)

来源

2013-03-05 vladimir

+1

后log.cat那里，我们能看到在发生异常时 – Gjordis 2013-03-05 08:19:22

+0

你能分享的logcat日志多久？ – lokoko 2013-03-05 08:19:39

+0

@Gjordis我已经更新了我的logcat的 – vladimir 2013-03-05 08:41:43

回答

0

你有没有在清单文件中获取许可？

<uses-permission android:name="android.permission.READ_PHONE_STATE" />

来源

2013-03-05 09:08:44

+0

不会是一个NPE而是IllegalStateException异常。 – sschrass 2013-03-05 09:37:50

+0

是的，我有这个权限 – vladimir 2013-03-05 10:10:18

相关问题

 相关问题