Apps setVisibility on a null object reference

Kurniawan · Jul 15, 2019

hello. i have error like this :

E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.yk.danaberkah, PID: 15413
java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.setVisibility(int)' on a null object reference
at com.yk.danaberkah.MainActivity.onNavigationItemSelected(MainActivity.java:154)
at com.google.android.material.navigation.NavigationView$1.onMenuItemSelected(NavigationView.java:170)
at androidx.appcompat.view.menu.MenuBuilder.dispatchMenuItemSelected(MenuBuilder.java:840)
at androidx.appcompat.view.menu.MenuItemImpl.invoke(MenuItemImpl.java:158)
at androidx.appcompat.view.menu.MenuBuilder.performItemAction(MenuBuilder.java:991)
at com.google.android.material.internal.NavigationMenuPresenter$1.onClick(NavigationMenuPresenter.java:352)
at android.view.View.performClick(View.java:4863)
at android.view.View$PerformClick.run(View.java:19981)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:135)
at android.app.ActivityThread.main(ActivityThread.java:5417)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:902)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:697)
I/Process: Sending signal. PID: 15413 SIG: 9
Application terminated.

this my MainActivity.java

Java:

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    LinearLayout kontenhome, kontendonasi, kontenwakaf, kontenzakat, kontennotifikasi, konteninformasi, kontensyaratdanketentuan;

@Override
protected void onCreate(Bundle savedInstanceState) {
    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);
    NavigationView navigationView = findViewById(R.id.nav_view);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
        this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.addDrawerListener(toggle);
    toggle.syncState();

@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) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
@Override
public boolean onNavigationItemSelected(MenuItem item) {
    // Handle navigation view item clicks here.
    int id = item.getItemId();

    if (id == R.id.nav_home) {
        kontenhome.setVisibility(View.VISIBLE);
        kontendonasi.setVisibility(View.GONE);
        kontenwakaf.setVisibility(View.GONE);
        kontenzakat.setVisibility(View.GONE);
        kontennotifikasi.setVisibility(View.GONE);
        konteninformasi.setVisibility(View.GONE);
        kontensyaratdanketentuan.setVisibility(View.GONE);
    }
    if (id == R.id.nav_donasi) {
        kontendonasi.setVisibility(View.VISIBLE);
        kontenhome.setVisibility(View.GONE);
        kontenwakaf.setVisibility(View.GONE);
        kontenzakat.setVisibility(View.GONE);
        kontennotifikasi.setVisibility(View.GONE);
        konteninformasi.setVisibility(View.GONE);
        kontensyaratdanketentuan.setVisibility(View.GONE);
    } else if (id == R.id.nav_wakaf) {
        kontenwakaf.setVisibility(View.VISIBLE);
        kontenhome.setVisibility(View.GONE);
        kontendonasi.setVisibility(View.GONE);
        kontenzakat.setVisibility(View.GONE);
        kontennotifikasi.setVisibility(View.GONE);
        konteninformasi.setVisibility(View.GONE);
        kontensyaratdanketentuan.setVisibility(View.GONE);

    } else if (id == R.id.nav_zakat) {
        kontenzakat.setVisibility(View.VISIBLE);
        kontenhome.setVisibility(View.GONE);
        kontendonasi.setVisibility(View.GONE);
        kontenwakaf.setVisibility(View.GONE);
        kontennotifikasi.setVisibility(View.GONE);
        konteninformasi.setVisibility(View.GONE);
        kontensyaratdanketentuan.setVisibility(View.GONE);

    } else if (id == R.id.nav_notification) {
        kontennotifikasi.setVisibility(View.VISIBLE);
        kontenhome.setVisibility(View.GONE);
        kontendonasi.setVisibility(View.GONE);
        kontenwakaf.setVisibility(View.GONE);
        kontenzakat.setVisibility(View.GONE);
        konteninformasi.setVisibility(View.GONE);
        kontensyaratdanketentuan.setVisibility(View.GONE);

    } else if (id == R.id.nav_informasi) {
        konteninformasi.setVisibility(View.VISIBLE);
        kontenhome.setVisibility(View.GONE);
        kontendonasi.setVisibility(View.GONE);
        kontenwakaf.setVisibility(View.GONE);
        kontenzakat.setVisibility(View.GONE);
        kontennotifikasi.setVisibility(View.GONE);
        kontensyaratdanketentuan.setVisibility(View.GONE);

    } else if (id == R.id.nav_syarat_dan_ketentuan) {
        kontensyaratdanketentuan.setVisibility(View.VISIBLE);
        kontenhome.setVisibility(View.GONE);
        kontendonasi.setVisibility(View.GONE);
        kontenwakaf.setVisibility(View.GONE);
        kontenzakat.setVisibility(View.GONE);
        kontennotifikasi.setVisibility(View.GONE);
        konteninformasi.setVisibility(View.GONE);

    }

    DrawerLayout drawer = findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;
}
}

setVisibility on a null object reference, why?
Thanks

wseng92 · Jul 15, 2019

You forgot to initialize all LinearLayout in onCreate method.

Kurniawan · Jul 15, 2019

i initialize like this but i found the same error, why?

Java:

navigationView.getMenu().getItem(0).setChecked(true);
kontenhome = findViewById(R.id.nav_home);
kontendonasi = findViewById(R.id.nav_donasi);
kontenwakaf = findViewById(R.id.nav_wakaf);
kontenzakat = findViewById(R.id.nav_zakat);
kontennotifikasi = findViewById(R.id.nav_notification);
konteninformasi = findViewById(R.id.nav_informasi);
kontensyaratdanketentuan = findViewById(R.id.nav_syarat_dan_ketentuan);

wseng92 · Jul 16, 2019

Make sure they are in activity_main.xml.

Kurniawan · Jul 16, 2019

wseng92 said:
Make sure they are in activity_main.xml.

i dont know still not working and the same error, thanks for ur help

Java:

public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    LinearLayout kontenhome, kontendonasi, kontenwakaf, kontenzakat, kontennotifikasi, konteninformasi, kontensyaratdanketentuan;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        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);
        NavigationView navigationView = findViewById(R.id.nav_view);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.addDrawerListener(toggle);
        toggle.syncState();
        navigationView.getMenu().getItem(0).setChecked(true);
        kontenhome = findViewById(R.id.nav_home);
        kontendonasi = findViewById(R.id.nav_donasi);
        kontenwakaf = findViewById(R.id.nav_wakaf);
        kontenzakat = findViewById(R.id.nav_zakat);
        kontennotifikasi = findViewById(R.id.nav_notification);
        konteninformasi = findViewById(R.id.nav_informasi);
        kontensyaratdanketentuan = findViewById(R.id.nav_syarat_dan_ketentuan);

    }

    @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) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
  
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();

        if (id == R.id.nav_home) {
            kontenhome.setVisibility(View.VISIBLE);
            kontendonasi.setVisibility(View.GONE);
            kontenwakaf.setVisibility(View.GONE);
            kontenzakat.setVisibility(View.GONE);
            kontennotifikasi.setVisibility(View.GONE);
            konteninformasi.setVisibility(View.GONE);
            kontensyaratdanketentuan.setVisibility(View.GONE);
        }
        if (id == R.id.nav_donasi) {
            kontendonasi.setVisibility(View.VISIBLE);
            kontenhome.setVisibility(View.GONE);
            kontenwakaf.setVisibility(View.GONE);
            kontenzakat.setVisibility(View.GONE);
            kontennotifikasi.setVisibility(View.GONE);
            konteninformasi.setVisibility(View.GONE);
            kontensyaratdanketentuan.setVisibility(View.GONE);
        } else if (id == R.id.nav_wakaf) {
            kontenwakaf.setVisibility(View.VISIBLE);
            kontenhome.setVisibility(View.GONE);
            kontendonasi.setVisibility(View.GONE);
            kontenzakat.setVisibility(View.GONE);
            kontennotifikasi.setVisibility(View.GONE);
            konteninformasi.setVisibility(View.GONE);
            kontensyaratdanketentuan.setVisibility(View.GONE);

        } else if (id == R.id.nav_zakat) {
            kontenzakat.setVisibility(View.VISIBLE);
            kontenhome.setVisibility(View.GONE);
            kontendonasi.setVisibility(View.GONE);
            kontenwakaf.setVisibility(View.GONE);
            kontennotifikasi.setVisibility(View.GONE);
            konteninformasi.setVisibility(View.GONE);
            kontensyaratdanketentuan.setVisibility(View.GONE);

        } else if (id == R.id.nav_notification) {
            kontennotifikasi.setVisibility(View.VISIBLE);
            kontenhome.setVisibility(View.GONE);
            kontendonasi.setVisibility(View.GONE);
            kontenwakaf.setVisibility(View.GONE);
            kontenzakat.setVisibility(View.GONE);
            konteninformasi.setVisibility(View.GONE);
            kontensyaratdanketentuan.setVisibility(View.GONE);

        } else if (id == R.id.nav_informasi) {
            konteninformasi.setVisibility(View.VISIBLE);
            kontenhome.setVisibility(View.GONE);
            kontendonasi.setVisibility(View.GONE);
            kontenwakaf.setVisibility(View.GONE);
            kontenzakat.setVisibility(View.GONE);
            kontennotifikasi.setVisibility(View.GONE);
            kontensyaratdanketentuan.setVisibility(View.GONE);

        } else if (id == R.id.nav_syarat_dan_ketentuan) {
            kontensyaratdanketentuan.setVisibility(View.VISIBLE);
            kontenhome.setVisibility(View.GONE);
            kontendonasi.setVisibility(View.GONE);
            kontenwakaf.setVisibility(View.GONE);
            kontenzakat.setVisibility(View.GONE);
            kontennotifikasi.setVisibility(View.GONE);
            konteninformasi.setVisibility(View.GONE);

        }

        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}

wseng92 · Jul 16, 2019

You don't know where you put your linear layout ? :thinking:

Richie Klepto · Jul 16, 2019

Is there an app or any way to access the ability to see and/or use hidden apps and functions on a Galaxy Note 9? I don't have a PC or a laptop to fix it by applying the code via the USB port...

wseng92 · Jul 17, 2019

Richie Klepto said:
Is there an app or any way to access the ability to see and/or use hidden apps and functions on a Galaxy Note 9? I don't have a PC or a laptop to fix it by applying the code via the USB port...

Sorry, that's not my area of expertise

Kurniawan · Jul 18, 2019

wseng92 said:
You don't know where you put your linear layout ?

ya i dont know, what exactly is it?

Kurniawan · Jul 18, 2019

Richie Klepto said:
Is there an app or any way to access the ability to see and/or use hidden apps and functions on a Galaxy Note 9? I don't have a PC or a laptop to fix it by applying the code via the USB port...

sorry i dont know, maybe you can ask on devices part.

wseng92 · Jul 18, 2019

You have to put all your linearLayout in activity_main.xml. Otherwise you will get null pointer exception since the compiler can't find the id.

Kurniawan · Jul 18, 2019

wseng92 said:
You have to put all your linearLayout in activity_main.xml. Otherwise you will get null pointer exception since the compiler can't find the id.

oh i know now, i placed the wrong id. i should put ID linear layout but i put ID on menu navigation. Thanks wseng92

wseng92 · Jul 18, 2019

Damn XD

Apps setVisibility on a null object reference

Kurniawan

Newbie

wseng92

Android Enthusiast

Kurniawan

Newbie

wseng92

Android Enthusiast

Kurniawan

Newbie

wseng92

Android Enthusiast

Richie Klepto

Lurker

wseng92

Android Enthusiast

Kurniawan

Newbie

Kurniawan

Newbie

wseng92

Android Enthusiast

Kurniawan

Newbie

wseng92

Android Enthusiast