How to add a button on the left side of android app toolbar?

Question

I want to add an **add-button on the left side of my android app toolbar

Answer 1

In YourActivity.java use this,

Toolbar toolbar = findViewById(R.id.Toolbar);
        toolbar.setTitle("ORDERS");
        setSupportActionBar(toolbar);
        Objects.requireNonNull(getSupportActionBar()).setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeAsUpIndicator(R.drawable.YOUR_IMAGE_NAME);

Use this outside of onCreate to set Click Listener to this Button

 @Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
        case android.R.id.home:
           

            Intent intent = new Intent(YourActivity.this, TargetActivity.class);
            intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_NEW_TASK);
            startActivity(intent);
            finish();
            return true;

        default:
            return super.onOptionsItemSelected(item);
    }
}

In activity_youractivity.xml layout use this,

<com.google.android.material.appbar.AppBarLayout
    android:id="@+id/AppbarLayout"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/Toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay" />
</com.google.android.material.appbar.AppBarLayout>

In styles.xml use this,

<resources>
<!-- Base application theme. -->
<style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
    <!-- Customize your theme here. -->
    <item name="colorPrimary">@color/colorPrimary</item>
    <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
    <item name="colorAccent">@color/colorAccent</item>
</style>
<style name="AppTheme.AppBarOverlay" parent="ThemeOverlay.AppCompat.Dark.ActionBar" />
</resources>

In build.gradle (app) use this,

implementation 'com.google.android.material:material:1.1.0'

Hope this helps. Feel free to ask for clarifications...