메뉴 바 여러 개 만들기

package com.example.navigation_menu_bar;
 
import android.os.Bundle;
 
import com.google.android.material.floatingactionbutton.FloatingActionButton;
import com.google.android.material.snackbar.Snackbar;
 
import android.view.View;
 
import androidx.core.view.GravityCompat;
import androidx.appcompat.app.ActionBarDrawerToggle;
 
import android.view.MenuItem;
 
import com.google.android.material.navigation.NavigationView;
 
import androidx.drawerlayout.widget.DrawerLayout;
 
import androidx.appcompat.app.AppCompatActivity;
import androidx.appcompat.widget.Toolbar;
import androidx.fragment.app.FragmentManager;
import android.app.Fragment;
 
import android.view.Menu;
 
public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {
 
    @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.setNavigationItemSelectedListener(this);
    }
 
    @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);
    }
 
    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
 
        FragmentManager manager = getSupportFragmentManager();
 
        if (id == R.id.nav_first_layout) {
            manager.beginTransaction().replace(R.id.content_main, new FirstLayout()).commit();
        } else if (id == R.id.nav_second_layout) {
            manager.beginTransaction().replace(R.id.content_main, new SecondLayout()).commit();
        } else if (id == R.id.nav_share) {
 
        } else if (id == R.id.nav_send) {
 
        }
 
        DrawerLayout drawer = findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;
    }
}