I’m getting an error when trying to implement an onClickListener, this is the error:
03-06 19:21:20.432: E/AndroidRuntime(1197): Caused by: java.lang.NullPointerException
03-06 19:21:20.432: E/AndroidRuntime(1197):at com.coursework.braintrain.Game.Easy12(Game.java:186)
and this is the line that is causing it: buttonhash.setOnClickListener(new OnClickListener(){
Basically I made buttonhash in the onCreate() method, but I want to make it so that when the button is pressed, it listens to whether the users input matches the actual answer of the equation. Maybe if I just put the code up it will make more sense (not good at explaining…)
public class Game extends Activity {
private static final String TAG = "Brain Training";
public static final String KEY_DIFFICULTY = "com.coursework.braintrain.difficulty";
public static final int DIFFICULTY_EASY = 0;
public static final int DIFFICULTY_MEDIUM = 1;
public static final int DIFFICULTY_HARD = 2;
public static final int DIFFICULTY_GURU = 3;
private int brain;
private EditText edittext;
private Button button1;
private Button button2;
private Button button3;
private Button button4;
private Button button5;
private Button button6;
private Button button7;
private Button button8;
private Button button9;
private Button button0;
private TextView answerLabel;
private Button buttonhash;
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
Log.d(TAG, "onCreate");
setContentView(R.layout.gamelayout);
int diff = getIntent().getIntExtra(KEY_DIFFICULTY, DIFFICULTY_EASY);
getGame(diff);
edittext = (EditText) findViewById(R.id.USERentry);
answerLabel = (TextView) findViewById(R.id.rightwrong_label);
button1 = (Button) findViewById(R.id.keypad_1);
button1.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
// Perform action on clicks
//String buttonText = (String) button.getText();
edittext.setText(edittext.getText() + "1");
//edittext.setText() = edittext.getText() + "1";
}
});
button2 = (Button) findViewById(R.id.keypad_2);
button2.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "2");
}
});
button3 = (Button) findViewById(R.id.keypad_3);
button3.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "3");
}
});
button4 = (Button) findViewById(R.id.keypad_4);
button4.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "4");
}
});
button5 = (Button) findViewById(R.id.keypad_5);
button5.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "5");
}
});
button6 = (Button) findViewById(R.id.keypad_6);
button6.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "6");
}
});
button7 = (Button) findViewById(R.id.keypad_7);
button7.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "7");
}
});
button8 = (Button) findViewById(R.id.keypad_8);
button8.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "8");
}
});
button9 = (Button) findViewById(R.id.keypad_9);
button9.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "9");
}
});
button0 = (Button) findViewById(R.id.keypad_0);
button0.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
edittext.setText(edittext.getText() + "0");
}
});
buttonhash = (Button) findViewById(R.id.keypad_hash);
//final Button buttonDel = (Button) findViewById(R.id.keypad_del);
//buttonDel.setOnClickListener(new OnClickListener(){
//public void onClick(View v){
//edittext.setText(edittext.getText() - 1);
//}
//});
}
private void getGame(int diff){
//TODO: Continue last game
switch(diff){
case DIFFICULTY_HARD:
break;
case DIFFICULTY_MEDIUM:
break;
case DIFFICULTY_EASY:
Easy12();
break;
}
//might require to return an array or something
}
public void Easy12(){
Random rand = new Random();
int a = (int) rand.nextInt(100)+1;
int b = (int) rand.nextInt(100)+1;
final TextView tv = (TextView) findViewById(R.id.question_label);
String aString = Integer.toString(a);
String bString = Integer.toString(b);
String display = aString + " + " + bString + " =";
tv.setText(display);
final int c = a + b;
buttonhash.setOnClickListener(new OnClickListener(){ //HERE IS THE ERROR!!
public void onClick(View v) {
if(edittext.getText().toString().equals(String.valueOf(c))){
answerLabel.setText(R.string.answer_correct);
answerLabel.setTextColor(R.color.correct_color);
//answerLabel.setBackgroundColor(R.color.background_answer);
}
else
{
answerLabel.setText(R.string.answer_wrong);
answerLabel.setTextColor(R.color.wrong_color);
//answerLabel.setBackgroundColor(R.color.background_answer);
}
}
});
}
}
My XML is fine if that is one of the things that might be causing it but I don’t think it has anything to do with it anyway 😛
So my problem is getting a nullpointerexception at the line where I set my buttonhash’s onClickListener, which is in another method (Easy12()). Any help on what might be causing this/how to fix it would be much appreciated. Thanks
You’re calling getGame() before defining your button, so it’s null.
Put the button declaration above getGame like this: