Android Studio记录一个错误：java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.

错误

java.lang.NullPointerException: Attempt to invoke virtual method ‘void android.widget.TextView.setText(java.lang.CharSequence)’ on a null object reference

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.dialogdownapplication, PID: 9769
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference
        at com.example.dialogdownapplication.DialogDown.setProgress(DialogDown.java:44)
        at com.example.dialogdownapplication.MainActivity$1.handleMessage(MainActivity.java:27)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6121)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:892)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:782)

解决

• 空指针异常
  可以找找：id的定义，对象/实例的初始化，事件的监听部分
• 点报错位置找到对应控件位置
  
• 检查id、定义、事件
  
  少了view
  因为并不是在Activity里面，所以修改如下

tvDialog = view.findViewById(R.id.tvDialog);
pbDialog = view.findViewById(R.id.pbDialog);

重新运行无报错