Java 这个错误不断出现

一开始一切都很好。但是一个月后，没有打开应用程序，出现了这个错误。我没有做任何更改。这就是错误，我试图修复它。但是，问题仍然存在

01-18 17:54:43.271: W/dalvikvm(1244): threadid=1: thread exiting with uncaught exception (group=0xb4a51b90)
01-18 17:54:44.401: D/dalvikvm(1244): GC_FOR_ALLOC freed 124K, 7% free 3060K/3272K, paused 764ms, total 782ms
01-18 17:54:44.401: E/AndroidRuntime(1244): FATAL EXCEPTION: main
01-18 17:54:44.401: E/AndroidRuntime(1244): Process: com.sabry.javabmi, PID: 1244
01-18 17:54:44.401: E/AndroidRuntime(1244): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.sabry.javabmi/com.sabry.javabmi.bmiLogger}: java.lang.NullPointerException
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2176)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2226)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.ActivityThread.access$700(ActivityThread.java:135)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1397)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.os.Handler.dispatchMessage(Handler.java:102)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.os.Looper.loop(Looper.java:137)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.ActivityThread.main(ActivityThread.java:4998)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at java.lang.reflect.Method.invokeNative(Native Method)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at java.lang.reflect.Method.invoke(Method.java:515)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:777)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:593)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at dalvik.system.NativeStart.main(Native Method)
01-18 17:54:44.401: E/AndroidRuntime(1244): Caused by: java.lang.NullPointerException
01-18 17:54:44.401: E/AndroidRuntime(1244):     at com.sabry.javabmi.bmiLogger.initializeApp(bmiLogger.java:60)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at com.sabry.javabmi.bmiLogger.onCreate(bmiLogger.java:37)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.Activity.performCreate(Activity.java:5243)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
01-18 17:54:44.401: E/AndroidRuntime(1244):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2140)
01-18 17:54:44.401: E/AndroidRuntime(1244):     ... 11 more
01-18 17:54:52.581: I/Process(1244): Sending signal. PID: 1244 SIG: 9

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错误在这里：

  btnChart.setEnabled( false );

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您尚未初始化/设置btnChart对象。

在下面的日志猫中，表示问题在第60行，这表明btnChart的初始化是一个问题。在代码中，没有显示btnChart初始化的位置

请在

bmiLogger.Java中初始化
btnChart
，然后检查

at dalvik.system.NativeStart.main(Native Method)
01-18 17:54:44.401: E/AndroidRuntime(1244): Caused by: java.lang.NullPointerException
01-18 17:54:44.401: E/AndroidRuntime(1244):     at com.sabry.javabmi.bmiLogger.initializeApp(bmiLogger.java:60)

我想您在使用按钮对象之前忘了初始化它

btnChart = (Button) findViewById(R.id.buttonId);

at
bmiLogger.java
的第60行是什么？该文件的第60行没有任何内容，但假设它是正确的文件，并且行号稍有偏离，我建议在尝试打开bmi_log.csv的地方中断，看看是否成功。
btnChart = (Button) findViewById(R.id.buttonId);