Showing launcher screen only once in Android

Question

I want to show launcher screen in Android app only once. Then if the user is on the second screen, if he presses back button, I want app to close. What's wrong in this code? The first screen shows again, what mustn't be.

public class MainActivity extends Activity {

    private boolean firstscreenshown=false; 

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        if (firstscreenshown==true) finish();
        firstscreenshown=true;

or

public class MainActivity extends Activity {

    private boolean firstscreenshown; 

    public MainActivity() {
        this.firstscreenshown = false;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        if (firstscreenshown==true) finish();
        firstscreenshown=true;

Answer 1

Use this code for handle back button in your MainActivity class:

@Override
    public void onBackPressed()
        {
            // TODO Auto-generated method stub
            super.onBackPressed();
            Intent startMain = new Intent(Intent.ACTION_MAIN);
            startMain.addCategory(Intent.CATEGORY_HOME);
            startMain.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(startMain);
        }