行Txt_EarnedPoint.getText（）拋出Nullpointer異常（textview） - 爲Android的Eclipse

Question

在Txt_EarnedPoint.getText（）行它拋出Nullpointer異常爲什麼？ Txt_EarnedPoint是一個textview。如果我刪除那條線，每個思考都能正常工作。 PLZ幫我...

 public class MainActivity extends ActionBarActivity implements 
      android.view.View.OnClickListener { 
     private TextView Txt_EarnedPoint; 
     private Button saveButton; 
     private Button DisableBtn; 
     private Button selectbutton; 

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


      TextView Txt_EarnedPoint=(TextView) findViewById(R.id.textView1); 
    public void GetImageId(int Imageid) { 
      else if (count == 1 
          && CheckBtnText == selectbutton.getText().toString()) { 
         selectbutton.setBackgroundResource(selectAptImage); 
         selectbutton.setEnabled(false); 
         count = 0; 
         IncCounter += 1; 
         saveButton.setText("0"); 
         selectbutton.setText("0"); 
--error part----------->Txt_EarnedPoint.getText(); 
         if (IncCounter == 6) { 
          AlertDialog d = new AlertDialog.Builder(this) 

            .setTitle("Completed Level 1") 
            .setMessage("Level Completed") 
            .setPositiveButton("Why should I stop Playing?", null) 
            .setNegativeButton("Tired to go on", null).show(); 
          HideAllButton(); 
         } 
    } 
    } 

Answer 1

而不是創建一個對象並將其分配給實例成員，您創建了被「遺忘」時的onCreate執行完畢的局部變量。

更改行：

TextView Txt_EarnedPoint=(TextView) findViewById(R.id.textView1);

要：

Txt_EarnedPoint=(TextView) findViewById(R.id.textView1);