android - 前のクラスに戻る物理ボタンを作成するにはどうすればよいですか

Question

   public boolean onKeyDown(int keyCode, KeyEvent event)  {
     if ((keyCode == KeyEvent.KEYCODE_BACK)) {
         moveTaskToBack(true);
         return true;
     }

     return super.onKeyDown(keyCode, event);
   }

こんにちは、前のクラスに戻るためのこのコードがありますが、戻るボタンを押すと、ホームランチャー画面が表示されます。アプリの前の画面に移動し、設定メニューで行った変更を保持したいと考えています。

Answer 1

moveTaskToBack() の代わりにこれを追加してみてください:

super.onBackPressed();

したがって、コードは次のようになります。

  public boolean onKeyDown(int keyCode, KeyEvent event)  {
     if ((keyCode == KeyEvent.KEYCODE_BACK)) {
         super.onBackPressed();
         return true;
     }

     return super.onKeyDown(keyCode, event);
   }

明らかに、アプリケーションの最初のアクティビティにいる場合は、ホーム画面に移動します

Answer 2

これが私の主な活動です

public class MainActivity extends FragmentActivity {

SectionsPagerAdapter mSectionsPagerAdapter;


ViewPager mViewPager;

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


    // Create the adapter that will return a fragment for each of the three
    // primary sections of the app.
    mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    // Set up the ViewPager with the sections adapter.
    mViewPager = (ViewPager) findViewById(R.id.pager);
    mViewPager.setAdapter(mSectionsPagerAdapter);

}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater inflater = getMenuInflater();
    inflater.inflate(R.menu.activity_main, menu);  
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle item selection
    switch (item.getItemId()) {
        case R.id.menu_settings4:
            mainactivity();
            return true;
        case R.id.menu_settings1:
            ipallilos();
            return true;
        case R.id.menu_settings2:
            rithmisi();
            return true;
        case R.id.menu_settings3:
            sxetika();
            return true;

        default:
            return super.onOptionsItemSelected(item);
    }

}

private void mainactivity() {

    Toast.makeText(MainActivity.this, "Επιστροφή στην Αρχική Σελίδα", 
            Toast.LENGTH_SHORT).show();
}
private void rithmisi() {
    setContentView(R.layout.rithmisis);
    Toast.makeText(MainActivity.this, "Loading Settings", 
            Toast.LENGTH_SHORT).show();
}

private void ipallilos() {
    setContentView(R.layout.ipallilos);
    Toast.makeText(MainActivity.this, "Loading Staff", 
            Toast.LENGTH_SHORT).show();
}

private void sxetika() {
    //anoigma menou efarmogis
    setContentView(R.layout.sxetikame);
    Toast.makeText(MainActivity.this, "Loading about Software", 
            Toast.LENGTH_SHORT).show();


}

 @Override
 public boolean onKeyDown(int keyCode, KeyEvent event)  {
     if ((keyCode == KeyEvent.KEYCODE_BACK)) {
         //moveTaskToBack(true);
         super.onBackPressed();
         return true;
     }

     return super.onKeyDown(keyCode, event);
 }




public class SectionsPagerAdapter extends FragmentPagerAdapter {

    public SectionsPagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        // getItem is called to instantiate the fragment for the given page.
        // Return a DummySectionFragment (defined as a static inner class
        // below) with the page number as its lone argument.
        Fragment fragment = new DummySectionFragment();
        Bundle args = new Bundle();
        args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, position + 1);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public int getCount() {
        // Show 3 total pages.
        return 2;
    }

    /**
     * εγω γράφεις τον τίτλο που θα φενεται
     * στο γραμμη το paper title
     */

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return getString(R.string.title_section1).toUpperCase();
           // case 1:
              //  return getString(R.string.title_section2).toUpperCase();
            case 1:
                return getString(R.string.title_section3).toUpperCase();
        }
        return null;
    }
}



/**
 * ΕΔΩ ΓΡΑΦΕΙΣ ΓΙΑ ΤΟ ΤΙ ΘΑ ΦΕΝΕΤΑΙ ΜΕΣΑ
 * 
 */
public static class DummySectionFragment extends Fragment {
    public DummySectionFragment() {
    }
    public static final String ARG_SECTION_NUMBER = "section_number";



    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {

        Bundle args = getArguments();
        switch (args.getInt(ARG_SECTION_NUMBER)){

        case 1: 
            return inflater.inflate(R.layout.paraggeleialayout, container, false);

        case 2:
             return inflater.inflate(R.layout.trapezia, container, false);

    }

        return getView();

}
}

}