Android底部导航栏

MainActivity.java

package com.example.bar;

import android.os.Bundle;
import android.view.MenuItem;

import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.fragment.app.Fragment;
import androidx.fragment.app.FragmentManager;
import androidx.fragment.app.FragmentTransaction;

import com.example.bar.fragment.HomeFragment;
import com.example.bar.fragment.MessagesFragment;
import com.example.bar.fragment.SettingsFragment;
import com.google.android.material.bottomnavigation.BottomNavigationView;

public class MainActivity extends AppCompatActivity {
    private BottomNavigationView bottomNavigationView;

    private HomeFragment homeFragment;
    private MessagesFragment messagesFragment;
    private SettingsFragment settingsFragment;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        getSupportActionBar().hide();//隐藏掉整个ActionBar

        // 初始化底部导航栏和Fragment
        bottomNavigationView = findViewById(R.id.bottom_navigation);
        homeFragment = new HomeFragment();
        messagesFragment = new MessagesFragment();
        settingsFragment = new SettingsFragment();

        // 默认显示HomeFragment
        setFragment(homeFragment);

        // 底部导航栏选中项变化的监听器
        bottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                switch (item.getItemId()) {
                    case R.id.action_home:
                        setFragment(homeFragment);
                        return true;
                    case R.id.action_messages:
                        setFragment(messagesFragment);
                        return true;
                    case R.id.action_settings:
                        setFragment(settingsFragment);
                        return true;
                }
                return false;
            }
        });
    }

    // 切换Fragment
    private void setFragment(Fragment fragment) {
        FragmentManager fragmentManager = getSupportFragmentManager();
        FragmentTransaction transaction = fragmentManager.beginTransaction();
        transaction.replace(R.id.container, fragment);
        transaction.commit();
    }
}

activity_mian.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <FrameLayout
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:background="@color/white"
        android:elevation="8dp"

        app:menu="@menu/bottom_navigation_menu" />
</RelativeLayout>

底部菜单

bottom_navigation_menu.xml

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <item
        android:id="@+id/action_home"
        android:icon="@drawable/football_roll_48"
        android:title="@string/bar_home"
        app:showAsAction="ifRoom"/>

    <item
        android:id="@+id/action_messages"
        android:icon="@drawable/messages_48"
        android:title="@string/bar_messages"

        app:showAsAction="ifRoom"/>

    <item
        android:id="@+id/action_settings"
        android:icon="@drawable/user"
        android:title="@string/bar_user"
        app:showAsAction="ifRoom"/>

</menu>

HomeFragment.java

package com.example.bar.fragment;


import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.fragment.app.Fragment;

import com.example.bar.R;

public class HomeFragment extends Fragment {
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_home, container, false);
    }
}

fragment_home.xml

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center">

    <TextView
        android:text="Home Page"
        android:textSize="30sp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

fragment_message、 fragment_settings类似

赏

谢谢你请我吃糖果