Android and Layout Tutorial — Optimize XML Layouts

Android UI performance is heavily affected by layout hierarchy and view nesting.

Deeply nested layouts can cause:

• Slow rendering
• Poor performance
• Long measure/layout passes
• Increased memory usage

Android provides:

• <merge>
• <include>

to optimize layouts and create reusable UI components efficiently.

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What Is <merge> in Android?

The:

<merge>

tag is used for:

• Reducing unnecessary layout nesting
• Optimizing view hierarchy
• Improving rendering performance

When a layout containing:

<merge>

is included inside another layout, the:

<merge>

node itself gets removed and only its child views are added directly to the parent.

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Why Use <merge>?

Without:

<merge>

developers often create unnecessary nested layouts such as:

LinearLayout
    └── LinearLayout
            └── Button

Extra nesting increases layout inflation cost.

Using:

<merge>

helps flatten the hierarchy.

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Example Without <merge>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="vertical">

    <Button
        android:text="Add"/>

    <Button
        android:text="Delete"/>

</LinearLayout>

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Optimized Example Using <merge>

<merge
    xmlns:android=
    "http://schemas.android.com/apk/res/android">

    <Button
        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="@string/add"/>

    <Button
        android:layout_width="match_parent"

        android:layout_height="wrap_content"

        android:text="@string/delete"/>

</merge>

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How <merge> Works Internally

Suppose:

• Parent layout includes child layout
• Child layout root is <merge>

Android removes the:

<merge>

container and directly inserts child views into the parent layout.

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Benefits of <merge>

• Flatter view hierarchy
• Faster rendering
• Reduced memory usage
• Improved UI performance
• Better layout optimization

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What Is <include> in Android?

The:

<include>

tag allows developers to reuse XML layouts across multiple screens.

This helps:

• Reduce duplicate code
• Improve maintainability
• Create reusable UI components
• Build modular layouts

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Why Use <include>?

Many applications reuse:

• Toolbar layouts
• Headers
• Footers
• Loading layouts
• Custom sections

Instead of rewriting the same XML repeatedly, developers can reuse layouts using:

<include>

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Create Reusable Layout

Example:

res/layout/layout_toolbar.xml

<merge
    xmlns:android=
    "http://schemas.android.com/apk/res/android">

    <TextView
        android:layout_width="wrap_content"

        android:layout_height="wrap_content"

        android:text="My Toolbar"

        android:textSize="20sp"/>

</merge>

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Using <include>

<include

    android:id="@+id/toolbarLayout"

    layout="@layout/layout_toolbar"/>

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How <include> Works

1. Android inflates reusable layout
2. Included layout inserted into parent
3. UI components become part of hierarchy

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Advantages of <include>

• Reusable UI
• Cleaner XML files
• Easier maintenance
• Consistent design system
• Reduced duplication

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Using <merge> with <include>

The best optimization pattern is:

• Reusable layout root = <merge>
• Parent layout uses <include>

This avoids unnecessary wrapper layouts.

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Real-World Example

Reusable toolbar layout:

layout_toolbar.xml

Included in:

• Home screen
• Profile screen
• Settings screen
• Dashboard screen

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Modern Android Recommendations

Modern Android applications now commonly use:

• ConstraintLayout
• ViewBinding
• DataBinding
• Jetpack Compose
• Reusable composables

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Jetpack Compose Alternative

Jetpack Compose replaces many XML reuse patterns using:

@Composable

functions.

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Compose Reusable UI Example

@Composable
fun ToolbarSection() {

    Text(
        text = "Toolbar"
    )
}

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When NOT to Use <merge>

Avoid:

<merge>

when:

• Layout needs its own background
• Root layout attributes are required
• Standalone inflation is needed

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Common Beginner Mistakes

1. Deeply Nested Layouts

Too many nested layouts reduce rendering performance.

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2. Forgetting Root Layout Requirements

<merge> removes the root node entirely.

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3. Duplicating XML Repeatedly

Reusable components should use:

<include>

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Performance Benefits

Without Optimization	With merge/include
Deep hierarchy	Flat hierarchy
Slower rendering	Faster rendering
Duplicate XML	Reusable layouts
More memory usage	Optimized memory usage

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FAQ

What is <merge> in Android?

<merge> removes unnecessary layout wrappers and optimizes hierarchy.

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What is <include> used for?

<include> allows reusing XML layouts across multiple screens.

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Can merge and include be used together?

Yes. Using them together provides excellent layout optimization.

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Conclusion

<merge> and <include> are powerful Android XML optimization tools that improve performance and maintainability.

They help developers create reusable layouts, reduce hierarchy depth, and optimize rendering performance in Android applications.

Modern Android applications should combine optimized layouts, AndroidX, ViewBinding, ConstraintLayout, and scalable UI architecture for production-grade performance.

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About the Author

Salil Jha is a Full Stack and Mobile Developer specializing in Android, React Native, fintech systems, scalable SaaS platforms, and developer tooling products.

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