小编lol*_*ubs的帖子

错误是:

java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{lol2dubs.stevemoa/lol2dubs.stevemoa.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference

代码是:

public class MainActivity extends AppCompatActivity {
double MOA;
TextView turretClicks = (TextView)findViewById(R.id.turretClicks);
boolean noMOA;

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



    EditText range = (EditText) findViewById(R.id.rangeEntry);
    String stringRange = range.getText().toString();
    int finalRange = Integer.parseInt(stringRange);
    if(finalRange <= 200) {
        MOA = 0;
    }
    if(finalRange > 200 && finalRange <= 225){
        MOA = .5;
    }
    if(finalRange > 225 && finalRange …