how to hide the float action button only on the 1st fragment?

Question

Please tell me how to hide the Floating Action button only on the 1st fragment in Android Studio? I use Navigation Drawer, here is a code in MainActivity.java where I call the fragments:

    public class MainActivity extends AppCompatActivity implements NavigationView.OnNavigationItemSelectedListener {

    FirstFragment fragment1;
    SecondFragment fragment2;
    ThirdFragment fragment3;
    


    @SuppressLint("StaticFieldLeak")
    public static Context currentContext;

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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = findViewById(R.id.fab);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });



        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
        navigationView.bringToFront();

        fragment1 = new FirstFragment();
        fragment2 = new SecondFragment();
        fragment3 = new ThirdFragment();
        
        getSupportFragmentManager().beginTransaction().add(R.id.nav_host_fragment, fragment1).commit();
        if (savedInstanceState==null){
           }

       
    }


    @Override
    public void onBackPressed() {
        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

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

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





@Override
    public boolean onNavigationItemSelected(MenuItem item) {
        int id = item.getItemId();
        FragmentTransaction ftrans = getSupportFragmentManager().beginTransaction();
        String title = "App Name";

        switch (id) {
            case (R.id.nav_fr2):
                ftrans.replace(R.id.nav_host_fragment, fragment2);
                title="Fragment 2";
                break;

            case (R.id.nav_fr3):
                ftrans.replace(R.id.nav_host_fragment, fragment3);
                title="Fragment 3";
                break;

           
            default:
                ftrans.replace(R.id.nav_host_fragment, fragment1);
                break;
        }
        getSupportActionBar().setTitle(title);
        ftrans.commit();
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }

Here is a code of my main activity. when I add fab.setVisibility(View.GONE); Android Studio display me an error "Cannot resolve symbol fab". When I add in this block FloatingActionButton fab = findViewById(R.id.fab); the fab not displayed in all fragments.

Answer 1

You can make your fab a class level variable instead of local and then change the visibility to your needs following is the example:

    FirstFragment fragment1;
    SecondFragment fragment2;
    ThirdFragment fragment3;



    @SuppressLint("StaticFieldLeak")
    public static Context currentContext;

    // declare it here
    FloatingActionButton fab;


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

        Toolbar toolbar = findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        //assign here like this
        fab = findViewById(R.id.fab);

        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });



        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
        navigationView.bringToFront();

        fragment1 = new FirstFragment();
        fragment2 = new SecondFragment();
        fragment3 = new ThirdFragment();

        getSupportFragmentManager().beginTransaction().add(R.id.nav_host_fragment, fragment1).commit();
        if (savedInstanceState==null){
        }


    }


    @Override
    public void onBackPressed() {
        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

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

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {

        int id = item.getItemId();
        return super.onOptionsItemSelected(item);
    }





    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        int id = item.getItemId();
        FragmentTransaction ftrans = getSupportFragmentManager().beginTransaction();
        String title = "App Name";

        switch (id) {
            case (R.id.nav_fr2):
                // set this visible when fragment 2 selected
                fab.setVisibility(View.VISIBLE);
                ftrans.replace(R.id.nav_host_fragment, fragment2);
                title="Fragment 2";
                break;

            case (R.id.nav_fr3):
                // set this visible when fragment 3 selected
                fab.setVisibility(View.VISIBLE);
                ftrans.replace(R.id.nav_host_fragment, fragment3);
                title="Fragment 3";
                break;


            default:
                // hide when fragment 1 selected
                fab.setVisibility(View.GONE);
                ftrans.replace(R.id.nav_host_fragment, fragment1);
                break;
        }
        getSupportActionBar().setTitle(title);
        ftrans.commit();
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }