Android-空数组。拔出时可在Android Studio模拟器中运行，但不能在真实设备上运行

我一直在通过Samsung S7手机（API 23和6.0.1）在Android Studio模拟器中测试我的应用程序，并且工作正常。当我从笔记本电脑上拔下电源并运行应用程序时，它崩溃了。

我的logcat说我正在尝试调用一个null数组...但是它不是null吗？我不明白为什么当我通过Android Studio在手机上运行该应用程序时一切正常，但是当我单独运行该应用程序时却崩溃了。感谢您的帮助！

这是我的日志

FATAL EXCEPTION: main
Process: com.example.abc.def, PID: 28693
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.abc.def/com.example.abc.def.MainActivity}: java.lang.NullPointerException: Attempt to read from null array
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3253)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3349)
at android.app.ActivityThread.access$1100(ActivityThread.java:221)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:158)
at android.app.ActivityThread.main(ActivityThread.java:7224)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120)
Caused by: java.lang.NullPointerException: Attempt to read from null array
at com.example.abc.def.MainActivity.onCreate(MainActivity.java:49)
at android.app.Activity.performCreate(Activity.java:6876)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1135)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3206)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3349) 
at android.app.ActivityThread.access$1100(ActivityThread.java:221) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1794) 
at android.os.Handler.dispatchMessage(Handler.java:102) 
at android.os.Looper.loop(Looper.java:158) 
at android.app.ActivityThread.main(ActivityThread.java:7224) 
at java.lang.reflect.Method.invoke(Native Method) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 

这是我的代码。当我调用btn1.setText（itemArray [0]）时，该问题出现在底部，因为该数组为“ null”

public class MainActivity extends AppCompatActivity {

Button btn1, btn2;
String btn1Name, btn2Name;
String btnValue = "", itemValue = "", itemPosition = "";
String[] buttonArray = new String[]{"blank", "blank"};
String[] itemArray = new String[]{"blank", "blank"};
String[] positionArray = new String[]{"blank", "blank"};  

@Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    btn1 = (Button) findViewById(R.id.button1);
    btn2 = (Button) findViewById(R.id.button2);

    Bundle extras = getIntent().getExtras();
    if (extras != null) {
        btnValue = extras.getString("btnValue");
        itemValue = extras.getString("itemValue");
        itemPosition = extras.getString("itemPosition");

        buttonArray = extras.getStringArray("buttonArray");
        itemArray = extras.getStringArray("array");
        positionArray = extras.getStringArray("positionArray");

        if (btnValue != null && btnValue.equals("btn1")){
            buttonArray[0] = btnValue;
            itemArray[0] = itemValue;
            positionArray[0] = itemPosition;
        } else if (btnValue != null && btnValue.equals("btn2")) {
            buttonArray[1] = btnValue;
            itemArray[1] = itemValue;
            positionArray[1] = itemPosition;
        }
    }

    btn1.setText(itemArray[0]);
    btn2.setText(itemArray[1]);
}
}