Question

当我运行我的应用程序时，它是Crush，那不是Java错误，但是它仍然是Crush并给我错误msg LogFile

我的AddReminderActivity.java文件

public class AddReminderActivity extends AppCompatActivity implements TimePickerDialog.OnTimeSetListener,
    DatePickerDialog.OnDateSetListener, LoaderManager.LoaderCallbacks<Cursor> {

private static final int EXISTING_VEHICLE_LOADER = 0;


private Toolbar mToolbar;
private EditText mTitleText;
private TextView mDateText, mTimeText, mRepeatText, mRepeatNoText, mRepeatTypeText;
private FloatingActionButton mFAB1;
private FloatingActionButton mFAB2 = (FloatingActionButton) findViewById(R.id.starred2);
private Calendar mCalendar;
private int mYear, mMonth, mHour, mMinute, mDay;
private long mRepeatTime;
private Switch mRepeatSwitch;
private String mTitle;
private String mTime;
private String mDate;
private String mRepeat;
private String mRepeatNo;
private String mRepeatType;
private String mActive;

private Uri mCurrentReminderUri;
private boolean mVehicleHasChanged = false;

// Values for orientation change
private static final String KEY_TITLE = "title_key";
private static final String KEY_TIME = "time_key";
private static final String KEY_DATE = "date_key";
private static final String KEY_REPEAT = "repeat_key";
private static final String KEY_REPEAT_NO = "repeat_no_key";
private static final String KEY_REPEAT_TYPE = "repeat_type_key";
private static final String KEY_ACTIVE = "active_key";


// Constant values in milliseconds
private static final long milMinute = 60000L;
private static final long milHour = 3600000L;
private static final long milDay = 86400000L;
private static final long milWeek = 604800000L;
private static final long milMonth = 2592000000L;

private View.OnTouchListener mTouchListener = new View.OnTouchListener() {
    @Override
    public boolean onTouch(View view, MotionEvent motionEvent) {
        mVehicleHasChanged = true;
        return false;
    }
};

这是LogFile消息

2019-07-09 14:54:00.947 8530-8530/com.delaroystudios.alarmreminder E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.delaroystudios.alarmreminder, PID: 8530
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.delaroystudios.alarmreminder/com.example.ghazalitodo.AddReminderActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2548)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
    at android.app.ActivityThread.-wrap12(ActivityThread.java)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
    at android.os.Handler.dispatchMessage(Handler.java:102)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.Window$Callback android.view.Window.getCallback()' on a null object reference
    at android.support.v7.app.AppCompatDelegateImplBase.<init>(AppCompatDelegateImplBase.java:117)
    at android.support.v7.app.AppCompatDelegateImplV9.<init>(AppCompatDelegateImplV9.java:149)
    at android.support.v7.app.AppCompatDelegateImplV11.<init>(AppCompatDelegateImplV11.java:29)
    at android.support.v7.app.AppCompatDelegateImplV14.<init>(AppCompatDelegateImplV14.java:54)
    at android.support.v7.app.AppCompatDelegateImplV23.<init>(AppCompatDelegateImplV23.java:31)
    at android.support.v7.app.AppCompatDelegateImplN.<init>(AppCompatDelegateImplN.java:31)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:198)
    at android.support.v7.app.AppCompatDelegate.create(AppCompatDelegate.java:183)
    at android.support.v7.app.AppCompatActivity.getDelegate(AppCompatActivity.java:519)
    at android.support.v7.app.AppCompatActivity.findViewById(AppCompatActivity.java:190)
    at com.example.ghazalitodo.AddReminderActivity.<init>(AddReminderActivity.java:51)
    at java.lang.Class.newInstance(Native Method)
    at android.app.Instrumentation.newActivity(Instrumentation.java:1078)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2538)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707) 
    at android.app.ActivityThread.-wrap12(ActivityThread.java) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460) 
    at android.os.Handler.dispatchMessage(Handler.java:102) 
    at android.os.Looper.loop(Looper.java:154) 
    at android.app.ActivityThread.main(ActivityThread.java:6077) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

Answer 1

使用findViewById设置布局后，您需要在mFAB2方法中为onCreate调用setContentView。

更改

private FloatingActionButton mFAB2 = (FloatingActionButton) findViewById(R.id.starred2);

到

private FloatingActionButton mFAB2;

在您的onCreate方法中

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(YOUR_LAYOUT);  // <- set the layout here

    mAddReminderButton = findViewById(R.id.fab); // <- use findViewById here after setContentView

    // rest of the code

尝试在空对象引用上调用虚拟方法'android.view.Window $ Callback android.view.Window.getCallback（）'{a-s}

1 个答案: