Button click works only once

Question

When I click my button it shows a random number but when I click it again nothing happens.How can I make the button show a random number everytime I click it?

public class MainActivity extends ActionBarActivity {

private int randomNumber;
private Button button;
private TextView numbersDisplayed;
private int[] allNumbers;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button)findViewById(R.id.button);
    numbersDisplayed = (TextView)findViewById(R.id.numbersDisplayed);

    allNumbers= new int[]{1,2,3,4,5,6,7,8,9};
    int numArrayLength = allNumbers.length;
    randomNumber = (int)(Math.random() * numArrayLength);

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.button:
                numbersDisplayed.setText(String.valueOf(allNumbers[randomNumber]));
                break;

            }
        }
    });
}


}

Answer 1

Move the logic required to generate a random number inside the onClick method (so it runs every time the button is clicked):

public class MainActivity extends ActionBarActivity {

private int randomNumber;
private Button button;
private TextView numbersDisplayed;
private int[] allNumbers;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button)findViewById(R.id.button);
    numbersDisplayed = (TextView)findViewById(R.id.numbersDisplayed);

    allNumbers= new int[]{1,2,3,4,5,6,7,8,9};
    int numArrayLength = allNumbers.length;

    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            switch (v.getId()) {
                case R.id.button:
                    randomNumber = (int)(Math.random() * numArrayLength);
                    numbersDisplayed.setText(String.valueOf(allNumbers[randomNumber]));
                    break;
            }
        }
    });
}

}