x
, y
and score
, so when the user rotates the screen then the values are retrieved and not regenerated.onSaveInstanceState
code that isn't working probably because of some @Override
coming into conflict with itMainActivity.java (without onSaveInstanceState
)
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
private EditText textBox;
private int z;
public int score = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
((TextView) findViewById(R.id.scoreText)).setText(R.string.nullScore);
textBox = findViewById(R.id.editText);
textBox.requestFocus();
setActual();
}
private void setActual() {
Random random = new Random();
int x = random.nextInt(10) + 1; //you get a random number between 0 and 9 then add 1 to get 1 - 10, no need to use array..
int y = random.nextInt(10) + 1;
z = x * y;
String hintStr = x + " × " + y;
((TextView) findViewById(R.id.hintTextView)).setText(hintStr);
}
public void onCheck(View view) {
int answer = Integer.parseInt(textBox.getText().toString());
String res = "Incorrect";
if (answer == z) {
res = "Correct";
score++;
Log.d("TAG", "Correct."); // right answer
textBox.setText("");
setActual(); // let's regenerate values
} else if (score == 0) {
Log.d("TAG", "Incorrect."); // wrong answer
textBox.setText("");
setActual();
((TextView) findViewById(R.id.scoreText)).setText(R.string.nullScore);
} else {
Log.d("TAG", "Incorrect."); // wrong answer
textBox.setText("");
score--;
setActual();
}
((TextView) findViewById(R.id.scoreText)).setText("Score:" + ' ' + score);
((TextView) findViewById(R.id.result_text_view)).setText(res);
}
}
MainActivity.java (with onSaveInstanceState
)
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.EditText;
import android.widget.TextView;
import java.util.Random;
public class MainActivity extends AppCompatActivity {
private EditText textBox;
private int z;
public int score = 0;
private int x;
private int y;
public void onSaveInstanceState(Bundle savedInstanceState) {
savedInstanceState.putInt("x", x);
savedInstanceState.putInt("y", y);
savedInstanceState.putInt("score", score);
}
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textBox = findViewById(R.id.editText);
textBox.requestFocus();
setActual();
if (savedInstanceState != null) {
x = savedInstanceState.getInt("x");
y = savedInstanceState.getInt("y");
score = savedInstanceState.getInt("score");
}
}
private void setActual() {
Random random = new Random();
x = random.nextInt(10) + 1; //you get a random number between 0 and 9 then add 1 to get 1 - 10, no need to use array..
y = random.nextInt(10) + 1;
z = x * y;
String hintStr = x + " × " + y;
((TextView) findViewById(R.id.hintTextView)).setText(hintStr);
}
public void onCheck(View view) {
int answer = Integer.parseInt(textBox.getText().toString());
String res = "Incorrect";
if (answer == z) {
res = "Correct";
score++;
Log.d("TAG", "Correct."); // right answer
textBox.setText("");
setActual(); // let's regenerate values
} else if (score == 0) {
Log.d("TAG", "Incorrect."); // wrong answer
textBox.setText("");
setActual();
((TextView) findViewById(R.id.scoreText)).setText(R.string.nullScore);
} else {
Log.d("TAG", "Incorrect."); // wrong answer
textBox.setText("");
score--;
setActual();
}
((TextView) findViewById(R.id.scoreText)).setText("Score:" + ' ' + score);
((TextView) findViewById(R.id.result_text_view)).setText(res);
}
}
You should consider calling super.onSaveInstanceState()
@Override
protected void onSaveInstanceState(@NonNull Bundle outState) {
// save your state
super.onSaveInstanceState(outState);
}
Also, to avoid recreating the activity everytime the screen is rotated you could handle config change yourself by adding this to your Activity declaration in the app manifest :
android:configChanges="keyboardHidden|orientation|screenSize"
And override :
@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
}
It could save time for the user if your app doesn't need to be recreated after orientation or screenSize changes...