How can the bottom menu bar functionality be implemented on Android?

In Android, we can achieve bottom navigation menu functionality by using the BottomNavigationView widget. Here are the steps to implement the bottom navigation menu.

1. First, add the BottomNavigationView control to the XML layout file as shown below:

<com.google.android.material.bottomnavigation.BottomNavigationView
    android:id="@+id/bottom_navigation"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:menu="@menu/bottom_menu" />

1. Create a folder named “menu” in the “res” directory and create an XML file inside it to define the bottom menu items. For example, create a file named “bottom_menu.xml” as shown below.

<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/menu_item1"
        android:title="Item 1"
        android:icon="@drawable/ic_item1" />
    <item
        android:id="@+id/menu_item2"
        android:title="Item 2"
        android:icon="@drawable/ic_item2" />
    <item
        android:id="@+id/menu_item3"
        android:title="Item 3"
        android:icon="@drawable/ic_item3" />
</menu>

1. In Activity or Fragment, obtain the BottomNavigationView widget and set a listener to handle the click events of the bottom menu items, as shown below:

BottomNavigationView bottomNavigationView = findViewById(R.id.bottom_navigation);
bottomNavigationView.setOnNavigationItemSelectedListener(item -> {
    switch (item.getItemId()) {
        case R.id.menu_item1:
            // 处理Item 1的点击事件
            return true;
        case R.id.menu_item2:
            // 处理Item 2的点击事件
            return true;
        case R.id.menu_item3:
            // 处理Item 3的点击事件
            return true;
        default:
            return false;
    }
});

By following the above steps, you can implement bottom navigation bar functionality in an Android application. When a user clicks on a bottom navigation item, the corresponding logic can be used to switch between interfaces or perform other operations.