Problems with RAM/Heap ussage. App Crashes on old Devices

Hey Everyone

I'm new here, i hope you can help me with my problems..

I developed an new App for something like a school, but i have a few problems with my app on older devices. Sometimes there crash with outOfMemory (Heap) Exception.. i already removed some large images, but the App still use a lot of the Heap Memory.

They also use ~85 mb of RAM, just to display Lot of Constrainet Layout, Text, Buttons & ImageViews (Just with Icons in it) and round about 10 Intents (Of course not at the same time )

Is there a way to reduce the amount of RAM/Heap Memory the App use?

Maybe someone can give me some tips how to code a bit more memory efficiency

I'll be glade if someone can help me !

Devices:
- Galaxy S7 (Android Version: current one, No problems at all)
- Galaxy S4 (Android version: 4.4, crashes)

Here is a little bit of my Code :< it's my first bigger project, so i think i make a lot of mistakes :'D

MainActivity:

public class ActivityMain extends AppCompatActivity {

private SharedPreferences sharedPreferences;
private SharedPreferences.Editor editor;

public static PackageInfo packageInfo;

private int infoCounter;

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

    //
    // Package Infos Laden

    try {
        packageInfo = getPackageManager().getPackageInfo(getPackageName(), 0);
    } catch (Exception ignored) {
    }

    ///////////////////////////////////////
    // Speichern / Laden vorbereiten

    sharedPreferences = PreferenceManager.getDefaultSharedPreferences(getApplicationContext());
    editor = sharedPreferences.edit();


    ///////////////////////////////////////
    // Menü Laden & Funktionen zuweisen

    SectionsPagerAdapter mSectionsPagerAdapter = new SectionsPagerAdapter(getSupportFragmentManager());

    ViewPager mViewPager = (ViewPager) findViewById(R.id.container);
    mViewPager.setAdapter(mSectionsPagerAdapter);

    TabLayout tabLayout = (TabLayout) findViewById(R.id.tabs);
    tabLayout.setupWithViewPager(mViewPager);

    FloatingActionButton floatingActionButton = (FloatingActionButton) findViewById(R.id.fab);
    floatingActionButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            openEmail();
        }
    });


    ///////////////////////////////////////
    // Informationstext anzeigen

    showInformation();


    ///////////////////////////////////////
    // Prüfen ob es sich um eine gekaufte Demo Version handelt

    if (!sharedPreferences.getString("key", "").isEmpty()) {
        if (Config.checkKey(sharedPreferences.getString("key", ""))) {
            Toast.makeText(getApplicationContext(), "Verifizierung erfolgreich!", Toast.LENGTH_SHORT).show();
            Config.isBuyed = true;
        }
        else {
            Toast.makeText(getApplicationContext(), "Verifizierung fehlgeschlagen!", Toast.LENGTH_SHORT).show();
            Config.isBuyed = false;
        }
    }  else {
        Config.isBuyed = false;
    }


    ///////////////////////////////////////
    // Werbung entsprechend laden

    if ((Constants.type == Constants.Type.FULL && Config.adFullversion) ||
            (Constants.type == Constants.Type.DEMO && !Config.isBuyed)) {
        AppBarLayout appBar = (AppBarLayout)findViewById(R.id.appbar);

        AdView mAdView = new AdView(this);
        mAdView.setLayoutParams(new FrameLayout.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT));
        //mAdView.setBackgroundColor(getResources().getColor(R.color.colorPrimary));
        mAdView.setAdSize(AdSize.BANNER);
        mAdView.setAdUnitId(getString(R.string.ad_banner_main));

        appBar.addView(mAdView);

        MobileAds.initialize(getApplicationContext(), "[PLACEHOLDER]");
        AdRequest.Builder adRequestBuilder = new AdRequest.Builder();
        if (Config.isDebug) {
            adRequestBuilder.addTestDevice(getString(R.string.ad_test_device));
        }
        AdRequest adRequest = adRequestBuilder.build();
        mAdView.loadAd(adRequest);
    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    int id = item.getItemId();

    if (id == R.id.action_settings) {
        return true;
    }
    if (id == R.id.action_info) {
        showInformation(true);
        return true;
    }

    return super.onOptionsItemSelected(item);
}

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 PlaceholderFragment (defined as a static inner class below).
        switch (position) {
            case 0:
                return FragmentMain.newInstance(position + 1);
            case 1:
                return FragmentInfo.newInstance(position + 1);
            case 2:
                return FragmentAbout.newInstance(position + 1);
            default:
                return FragmentMain.newInstance(1);
        }

    }

    @Override
    public int getCount() {
        return 3;
    }

    @Override
    public CharSequence getPageTitle(int position) {
        switch (position) {
            case 0:
                return getString(R.string.tab01);
            case 1:
                return getString(R.string.tab02);
            case 2:
                return getString(R.string.tab03);
        }
        return null;
    }
}

//////////////////////////////////////////
// Extern Functions

public void switchActivity(View view) {
    Intent intent = null;
    switch (view.getId()) {
        case  R.id.image_menu_bfw:
            intent = new Intent(this, ActivityBFW.class);
            break;
        default:
            Log.d("ERROR", "CANT START INTENT!");
            break;
    }
    if (intent != null)
        startActivity(intent);
    intent = null;
    // TODO: Passende Animation finden & Rückweg fixen (OnPressBack Button in Intent?)
    // overridePendingTransition(R.anim.bottom_to_top, R.anim.stay);
}

private void showInformation() {
    showInformation(false);
}

private void showInformation(boolean ignoreCounter) {
    infoCounter = sharedPreferences.getInt("infoCounter", 3);

    if ((infoCounter > 0) || ignoreCounter) {
        AlertDialog alertDialog = new AlertDialog.Builder(this).create();
        alertDialog.setTitle("Information");
            alertDialog.setMessage(getResources().getString(R.string.label_error_information) + (!ignoreCounter ? "\n\nVerbleibende Einblendungen: " + (infoCounter - 1) : ""));
        alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, "OK", new DialogInterface.OnClickListener() {
            @Override
            public void onClick(DialogInterface dialog, int which) {
                editor.putInt("infoCounter", --infoCounter);
                editor.commit();
            }
        });
        alertDialog.show();
    }
}

private void openEmail() {
    Intent intent;
    intent = new Intent(this, ActivityEmail.class);
    startActivity(intent);
}

public void exitApplication() {
    Intent intent = new Intent(Intent.ACTION_MAIN);
    intent.addCategory(Intent.CATEGORY_HOME);
    intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
    startActivity(intent);
}

public void openApp(View view) {
    Intent intent = new Intent(Intent.ACTION_VIEW);
    intent.setData(Uri.parse("market://details?id=de.*.*.*"));
    startActivity(intent);
}

//////////////////////////////////////////
// Dialogs

public void showDialog(String title, String message, String buttonText) {
    AlertDialog alertDialog = new AlertDialog.Builder(this).create();
    alertDialog.setTitle(title);
    alertDialog.setMessage(message);
    alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, buttonText, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {

        }
    });
    alertDialog.show();
}

public void showCloseDialog(String title, String message, String buttonText) {
    AlertDialog alertDialog = new AlertDialog.Builder(this).create();
    alertDialog.setTitle(title);
    alertDialog.setMessage(message);
    alertDialog.setButton(AlertDialog.BUTTON_NEUTRAL, buttonText, new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            Intent intent = new Intent(Intent.ACTION_MAIN);
            intent.addCategory(Intent.CATEGORY_HOME);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(intent);
        }
    });
    alertDialog.show();
}

public void register(View view) {
    Intent intent = new Intent(this, ActivityRegister.class);
    startActivity(intent);
}

}

An other important Activity:

public class ActivityBFW extends AppCompatActivity {

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

public void switchActivity(View view) {
    Intent intent = null;
    switch (view.getId()) {
        case R.id.image_menu_eating:
            intent = new Intent(this, ActivityEating.class);
            break;
        case R.id.image_menu_gym:
            intent = new Intent(this, ActivityGYM.class);
            break;
        case R.id.image_menu_fitness:
            intent = new Intent(this, ActivityFitness.class);
            break;
        case R.id.image_menu_pool:
            intent = new Intent(this, ActivityPool.class);
            break;
        case R.id.image_menu_shop:
            intent = new Intent(this, ActivityShop.class);
            break;
        default:
            Log.d("ERROR", "CANT START INTENT!");
            break;
    }
    if (intent != null)
        startActivity(intent);
    intent = null;
    // TODO: Passende Animation finden & Rückweg fixen (OnPressBack Button in Intent?)
    // overridePendingTransition(R.anim.bottom_to_top, R.anim.stay);
}

}

— modified on Apr 21, 2017, 8:49:58 PM