Recyclerview efficiency

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RecyclerView Efficiency Deep Dive

Overview

RecyclerView is efficient because it reuses view holders, minimizes view inflation, and delegates layout/animations to specialized components.

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Why RecyclerView Beats ListView

• ViewHolder pattern is first-class.
• Better recycling and pooling.
• Flexible LayoutManager implementations.
• Built-in animation and diff-friendly update patterns.

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Core Components

• RecyclerView
• Adapter
• ViewHolder
• LayoutManager
• Optional ItemAnimator and ItemDecoration

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Performance Practices

• Use ListAdapter + DiffUtil.
• Keep onBindViewHolder() lightweight.
• Avoid nested heavy layouts in item XML.
• Use stable IDs when appropriate.
• Pre-size image requests and cache aggressively.

class UserAdapter : ListAdapter<User, UserVH>(UserDiff()) {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): UserVH =
        UserVH(ItemUserBinding.inflate(LayoutInflater.from(parent.context), parent, false))

    override fun onBindViewHolder(holder: UserVH, position: Int) {
        holder.bind(getItem(position))
    }
}

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Interview Traps

• Calling notifyDataSetChanged() too often hurts performance.
• Doing expensive formatting or image decoding in bind causes jank.

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Key Takeaways

• RecyclerView performance is mostly about efficient bind work and diffed updates.
• Good item layout design matters as much as adapter logic.