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
