Android-RecyclerView系列 notifyItemChanged() - 实现单选选中状态更新

Posted 2021-07-23 彭老希

一、效果图

二、使用

public class MainActivity extends AppCompatActivity {
 
    List<String> mData = new ArrayList<>();
    RecyclerView recyclerView;
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }
 
    private void init() {
        recyclerView = findViewById(R.id.recycler_view);
        for (int i = 0; i < 30; i++) {
            mData.add("A-"+i);
        }
        recyclerView.setLayoutManager(new LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false));
        recyclerView.setAdapter(new ItemAdapter());
 
        //notifyItemChanged() 默认有动画
        //去掉默认刷新动画
        ((DefaultItemAnimator) recyclerView.getItemAnimator()).setSupportsChangeAnimations(false);
    }
 
    class ItemAdapter extends RecyclerView.Adapter<ItemAdapter.ViewHolder>{
 
        int currentIndex = 0;//小技巧： 默认等于0 则默认选中第一项 默认等于<0 则默认不选中
        @NonNull
        @Override
        public ViewHolder onCreateViewHolder(@NonNull ViewGroup viewGroup, int i) {
            return new ViewHolder(LayoutInflater.from(MainActivity.this).inflate(R.layout.item_layout,viewGroup,false));
        }
 
        @Override
        public void onBindViewHolder(@NonNull ViewHolder viewHolder, final int position) {
            String text = mData.get(position);
            viewHolder.textView.setText(text);
            if (currentIndex == position){
                viewHolder.textView.setBackgroundColor(Color.RED);
            }else {
                viewHolder.textView.setBackgroundColor(Color.WHITE);
            }
            viewHolder.textView.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    int lastIndex = currentIndex;
                    currentIndex = position;
                    notifyItemChanged(currentIndex);
                    if (!(lastIndex<0)){
                        notifyItemChanged(lastIndex);
                    }
                }
            });
        }
 
        @Override
        public int getItemCount() {
            return mData.size();
        }
 
        class ViewHolder extends RecyclerView.ViewHolder{
 
            TextView textView;
            public ViewHolder(@NonNull View itemView) {
                super(itemView);
                textView = itemView.findViewById(R.id.text_view);
            }
        }
    }
}