使用 CollapsingToolbar 滚动时如何更新工具栏

Question

I'm trying to move from one TextView to the Toolbar when it collapse when scrolling.

Let's say I have a Toolbar and just below of it I have a View, when I scroll up and it starts to not be visible at all I want to update the toolbar with this text, here's an example.

I've been reading with the CollapsingToolbar but I can figure it out when the view is not that visible and if I have to create like a custom Toolbar with a text at the right where I can set, because it's not the title, it's an extra value of the title.

Answer 1

where I can set, because it's not the title, it's an extra value of the title.

You can use the title for a customized Toolbar as supportActionBar ; but adjust the scrolling flags appropriately to the toolbar & the layout behaviour to the main layout.

if I have to create like a custom Toolbar with a text at the right

To set the title to the right; there are 2 properties, one for the collapsed text, and the other for the expanded, you need to align them to the end/right:

app:collapsedTitleGravity="end"
app:expandedTitleGravity="end"

Here is a demo:

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">


    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appbarlayout"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:paddingEnd="8dp"
        android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

        <com.google.android.material.appbar.CollapsingToolbarLayout
            android:id="@+id/collapsing_toolbar"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            app:collapsedTitleGravity="end"
            app:contentScrim="?attr/colorPrimary"
            app:expandedTitleGravity="end"
            app:layout_scrollFlags="scroll|exitUntilCollapsed"
            app:title="Hi">

            <LinearLayout
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:orientation="vertical"
                app:layout_collapseMode="parallax" />

            <androidx.appcompat.widget.Toolbar
                android:id="@+id/toolbar"
                android:layout_width="match_parent"
                android:layout_height="?attr/actionBarSize"
                app:layout_collapseMode="pin"
                app:layout_scrollFlags="scroll|enterAlways|snap"
                app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
                app:title="Hi"
                app:titleTextColor="#fff" />

        </com.google.android.material.appbar.CollapsingToolbarLayout>

    </com.google.android.material.appbar.AppBarLayout>


    <!--    Main Layout -->

    <androidx.core.widget.NestedScrollView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_behavior="@string/appbar_scrolling_view_behavior"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/appbarlayout">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/long_text" />

    </androidx.core.widget.NestedScrollView>


</androidx.coordinatorlayout.widget.CoordinatorLayout>

Make sure to use a NoActionBar theme, and set the custom Toolbar as the supportActionBar :

val toolbar = findViewById<Toolbar>(R.id.toolbar)
setSupportActionBar(toolbar)