機器人 - 了java.lang.RuntimeException

Question

爲什麼我會得到一個了java.lang.RuntimeException：無法實例activityComponentInfo {com.example.carprofile/com.example.carprofile.CarRegistraion}：java.lang.NullPointerExceprion

這是我的代碼：

public class CarRegistration extends Activity{ 

//ParseXML parseClass; 
Button saveCar; 
EditText carMake = (EditText) findViewById(R.id.etCarMake); 
EditText carModel = (EditText) findViewById(R.id.etCarModel); 
String newCar; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    // TODO Auto-generated method stub 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.car_registration); 

    saveCar = (Button) findViewById(R.id.bSaveCar); 
    saveCar.setOnClickListener(new OnClickListener() { 

     @Override 
     public void onClick(View v) { 
      newCar = carMake.getText() +" "+ carModel.getText(); 
      //parseClass = new ParseXML(newCar); 
      //parseClass.editXML(); 
     } 
    }); 
} 

如果我清除了onCreate方法，從saveCar =（Button）...，一切工作正常。

有人能告訴我我做錯了什麼嗎？

Answer 1

試試這個，

public class CarRegistration extends Activity{ 

    Button saveCar; 
    String newCar; 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
// TODO Auto-generated method stub 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.car_registration); 

    EditText carMake = (EditText) findViewById(R.id.etCarMake); //these lines should be  after setContentView() 
    EditText carModel = (EditText) findViewById(R.id.etCarModel); 
    saveCar = (Button) findViewById(R.id.bSaveCar); 
    saveCar.setOnClickListener(new OnClickListener() { 

    @Override 
    public void onClick(View v) { 
     newCar = carMake.getText() +" "+ carModel.getText(); 
     //parseClass = new ParseXML(newCar); 
     //parseClass.editXML(); 
    } 
}); 

}