NullPointerException当打开活动

只要我打开我的数据库与其他一些东西一起打开活动，我的应用程序崩溃与NullPointerException。NullPointerException当打开活动

我按下了一个打开此活动的按钮，WorkoutEdit.java立即崩溃。

import android.app.Activity; 
import android.app.AlertDialog; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.database.Cursor; 
import android.os.Bundle; 
import android.text.InputType; 
import android.view.View; 
import android.view.WindowManager; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.RadioGroup; 
import android.widget.RadioGroup.OnCheckedChangeListener; 
import android.widget.TextView; 
import android.widget.ViewFlipper; 

public class WorkoutEdit extends Activity { 

    public TextView mTitleText; 
    //private EditText mBodyText; 
    private Long mRowId; 
    private StrongDbAdapter mDbHelper; 
    private ViewFlipper viewFlipper; 
    public TextView squats; 
    public boolean workoutA; 
    public String workoutState; 
    //private double rowId = mRowId; 
    public String squatLabel; 
    public Button confirmButton; 




    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.workout_edit3); 

     mDbHelper = new StrongDbAdapter(this); 


      mDbHelper.open(); 


     setTitle(R.string.edit_workout); 

     mTitleText = (TextView) findViewById(R.id.workout_row); 
     //mBodyText = (EditText) findViewById(R.id.body); 
     viewFlipper = (ViewFlipper) findViewById(R.id.viewFlipper); 
     squats = (TextView) findViewById(R.id.squatLabel); 
     final AlertDialog.Builder alert = new AlertDialog.Builder(this); 
     squatLabel = squats.getText().toString(); 



     confirmButton = (Button) findViewById(R.id.confirmButton); 

     mRowId = (savedInstanceState == null) ? null : 
      (Long) savedInstanceState.getSerializable(StrongDbAdapter.KEY_ROWID); 
     if (mRowId == null) { 

      getWorkoutState(); 
      if(workoutA == true){ 
       workoutState = "WorkoutA"; 
      }else{ 
       workoutState = "WorkoutB"; 
      } 

      Bundle extras = getIntent().getExtras(); 
      mRowId = extras != null ? extras.getLong(StrongDbAdapter.KEY_ROWID) 
            : null; 
     } 


     // populateFields(); 

     confirmButton.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View view) { 
       setResult(RESULT_OK); 
       finish(); 
      } 

     }); 



     squats.setOnClickListener(new View.OnClickListener() { 

      public void onClick(View v) { 
       // TODO Auto-generated method stub 

       alert.setTitle("Squats"); 
       alert.setMessage("Message"); 

       //AlertDialog dialog = alert.create(); 

       //set an EditText view to get user input 
       final EditText input = new EditText(aMethod()); 
       input.setInputType(InputType.TYPE_CLASS_NUMBER); 

       //dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE); 

       alert.setView(input); 

       alert.setPositiveButton("Ok", new DialogInterface.OnClickListener(){ 
        public void onClick(DialogInterface dialog, int whichButton){ 
         String value = input.getText().toString(); 
         //Do something with value 

         value = "Squats - " + value; 

         squats.setText(value); 

        }       
       }); 

       alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener(){ 
        public void onClick(DialogInterface dialog, int whichButton){ 
         //Cancelled 
        } 
       }); 

       AlertDialog dialog = alert.create(); 

       dialog.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_VISIBLE); 



       //alert.show(); 
       dialog.show(); 

      } 
     }); 


     RadioGroup radioGroup = (RadioGroup) findViewById(R.id.radgroup1); 




     radioGroup.setOnCheckedChangeListener(new OnCheckedChangeListener(){ 
      public void onCheckedChanged(RadioGroup group, int checkedId) 
      { 
       switch(checkedId) 
       { 
        case(R.id.rad2): 
         viewFlipper.setDisplayedChild(1); 
        break; 
        case(R.id.rad3): 
         viewFlipper.setDisplayedChild(2); 
        break; 
        default: 
         viewFlipper.setDisplayedChild(0); 
        break; 
       } 
      } 
     });  

     //saveState(); 



     if((Long)(mRowId-1) == null){ 
      squats.setText("Squats - 45"); 
     }else{ 
      Cursor note = mDbHelper.fetchNote((Long)(mRowId-1)); 
      startManagingCursor(note); 
      squats.setText(note.getString(
        note.getColumnIndexOrThrow(StrongDbAdapter.SQUAT_LABEL))); 
      String squat = squats.getText().toString(); 
      int squatsWeight = Integer.parseInt(squat); 
      squatsWeight = squatsWeight + 5 ; 
      squats.setText("Squats - " + squatsWeight); 
     } 




//end of onCreate 
    } 
    /* 
    private void populateFields() { 
     if (mRowId != null) { 
      Cursor note = mDbHelper.fetchNote(mRowId); 
      startManagingCursor(note); 
      mTitleText.setText(note.getString(
        note.getColumnIndexOrThrow(StrongDbAdapter.KEY_TITLE))); 
      workoutState=(note.getString(
        note.getColumnIndexOrThrow(StrongDbAdapter.WORKOUT_STATE))); 
      squats.setText(note.getString(note.getColumnIndexOrThrow(StrongDbAdapter.SQUAT_LABEL))); 
     } 
    } 
    */ 


    @Override 
    protected void onSaveInstanceState(Bundle outState) { 
     super.onSaveInstanceState(outState); 
     //saveState(); 
     //outState.putSerializable(StrongDbAdapter.KEY_ROWID, mRowId); 
    } 

    @Override 
    protected void onPause() { 
     super.onPause(); 
     //saveState(); 
    } 

    @Override 
    protected void onResume() { 
     super.onResume(); 
     //populateFields(); 
    } 



    //Saves all the data to the database 
    private void saveState() { 
     String title = workoutState; 
     String squatLabel = squats.getText().toString(); 


     if (mRowId == null) { 
      long id = mDbHelper.createNote(title, squatLabel); 
      if (id > 0) { 
       mRowId = id; 
      } 
     } else { 
      mDbHelper.updateNote(mRowId, title); 
     } 
    }  

    public Context aMethod(){ 
     Context actContext = this; 
     return actContext; 
    } 

    public boolean getWorkoutState(){ 
     if(workoutA!=false){ 
      workoutA = true; 
     }else{ 
      workoutA = false; 
     } 


     return workoutA; 

    } 




}

这里是我的logcat日志：

08-04 20:12:27.682: E/AndroidRuntime(23360): FATAL EXCEPTION: main 
08-04 20:12:27.682: E/AndroidRuntime(23360): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.anapoleon.android.stronglifts/com.anapoleon.android.stronglifts.WorkoutEdit}: java.lang.NullPointerException 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1872) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1893) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.ActivityThread.access$1500(ActivityThread.java:135) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.ActivityThread$H.handleMessage(ActivityThread.java) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.os.Handler.dispatchMessage(Handler.java) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.os.Looper.loop(Looper.java) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.ActivityThread.main(ActivityThread.java:4385) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at java.lang.reflect.Method.invokeNative(Native Method) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at java.lang.reflect.Method.invoke(Method.java:507) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at dalvik.system.NativeStart.main(Native Method) 
08-04 20:12:27.682: E/AndroidRuntime(23360): Caused by: java.lang.NullPointerException 
08-04 20:12:27.682: E/AndroidRuntime(23360): at com.anapoleon.android.stronglifts.WorkoutEdit.onCreate(WorkoutEdit.java:166) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java) 
08-04 20:12:27.682: E/AndroidRuntime(23360): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1836) 
08-04 20:12:27.682: E/AndroidRuntime(23360): ... 11 more

来源

2012-08-05 user1576752

你能指出WorkoutEdit.java中的第166行吗？这是你的NullPointerException ... – BrainCrash 2012-08-05 00:39:14

Ahhh它的这个“if（（Long）（mRowId-1）== null）{”我需要检查我的数据库中的前一个值是否为null，并且唯一的方法是获取它编译时将其转换为Long – user1576752 2012-08-05 00:43:52

存在解释错误：“Long mRowId”不是数组。你可以通过并检查以前的值。 – 2012-08-05 02:09:53

所以......你mRowId可以在你的代码中设置为空，但你不检查它在该行空状态166

还要注意（Long）（mRowId-1）== null永远不会成立。

来源

2012-08-05 00:55:32 BrainCrash

我可能会误解你，但在第166行中，我试图查看当前mRowId之前的id *是否为空，以便我可以设置标准值或根据以前mRowId的值创建一个值。 – user1576752 2012-08-05 00:58:50

如果编译器遇到null-1（mRowId-1），它将返回一个NullPointerException ... – BrainCrash 2012-08-05 01:09:44

你在166行条件不具备任何意义：

(Long)(mRowId-1) == null

如果mRowid不为空，然后(Long)(mRowId-1)绝不会空，但如果mRowid是空，则您将收到NullPointerException，因为null - 1不正确。

所以你不会在当前mRowId

你可能想使用一些其他施工前得到任何形式

的ID。

来源

2012-08-05 01:20:31 Prizoff

谢谢你，我发现了一个解决方法 – user1576752 2012-08-05 02:43:36

NullPointerException当打开活动

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