Android Log.d（字符串，字符串）使我的程序崩溃？

如果我将此代码添加到我的任何方法中，以检查片段是否为null；我的程序崩溃了。但是如果我注释掉Log.d（），程序不会崩溃吗

这里可能出了什么问题

if(cyclefragment.equals(null)){
        Log.d("TESTING CYCLEFRAG NULL", "CycleFrag is null");
        }else{
            Log.d("TESTING CYCLEFRAG NULL", "CycleFrag is not null");
        }
        if(cyclefragment.a1.equals(null)){
            Log.d("TESTING A1 NULL", "A1 is null");
        }else{
            Log.d("TESTING A1 NULL", "A1 is not null");
        }

LogCat:

 03-24 03:37:27.461: E/Trace(13979): error opening trace file: No such file or directory (2)
03-24 03:37:27.928: E/AndroidRuntime(13979): FATAL EXCEPTION: main
03-24 03:37:27.928: E/AndroidRuntime(13979): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nanospark.upcdemo/com.nanospark.upcdemo.MainActivity}: java.lang.NullPointerException
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2184)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2211)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.ActivityThread.access$600(ActivityThread.java:149)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1300)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.os.Handler.dispatchMessage(Handler.java:99)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.os.Looper.loop(Looper.java:153)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.ActivityThread.main(ActivityThread.java:4987)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at java.lang.reflect.Method.invokeNative(Native Method)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at java.lang.reflect.Method.invoke(Method.java:511)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:821)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:584)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at dalvik.system.NativeStart.main(Native Method)
03-24 03:37:27.928: E/AndroidRuntime(13979): Caused by: java.lang.NullPointerException
03-24 03:37:27.928: E/AndroidRuntime(13979):    at com.nanospark.upcdemo.MainActivity.onCreate(MainActivity.java:75)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.Activity.performCreate(Activity.java:5020)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
03-24 03:37:27.928: E/AndroidRuntime(13979):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2148)
03-24 03:37:27.928: E/AndroidRuntime(13979):    ... 11 more

试试这个

如果实际导致问题的条件不是

log.d（）

---

我解决了我的问题；我从未在cyclefragment类中实例化字段a1。抱歉，伙计们。

我猜是if条件导致了崩溃，而不是log d可能是..那么，如果我只注释掉log.d而没有任何条件，它将如何工作呢？if（cyclefragment.a1.equals（null））{我解决了我的问题；我从未在cyclefragment类中实例化字段a1。请不要自行破坏您的帖子。没有问题的答案将变得毫无用处。我告诉过您这是问题的if！

    if(cyclefragment == null){
        Log.d("TESTING CYCLEFRAG NULL", "CycleFrag is null");
    }else{
        Log.d("TESTING CYCLEFRAG NULL", "CycleFrag is not null");
    }
    if(cyclefragment.a1 == null){
        Log.d("TESTING A1 NULL", "A1 is null");
    }else{
        Log.d("TESTING A1 NULL", "A1 is not null");
    }