ListView 单条item刷新

listView列表刷新某一条数据时采用notifyDataSetChanged()代价有点高，最好能 局部刷新 。局部刷新的 重点 是， 找到要更新的那项的View，然后再根据业务逻辑更新数据即可 。

大概就是3步：

1.找到要更新的那条数据的item 对于的view

因为listView条目的复用，所以当前点击的位置对应的条目为position- FirstVisiblePosition

2.获取该item中对于的相关View ，修改相关view显示的值

3.获取该item中对于的相关View ，修改相关view显示的值
举个例子：

public class ListAdapter extends BaseAdapter{
    private List<Person> mList;
    private Context mContext;
    private int count=0;

    public ListAdapter(List<Person> list) {
        mList = list;
    }

    @Override
    public int getCount() {
        return mList!=null?mList.size():0;
    }

    @Override
    public Object getItem(int position) {
        return mList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        count++;
        Log.d("getView被调用的次数===",count+"");
        mContext=parent.getContext();
        ViewHolder holder=null;
        if(convertView==null){
            holder=new ViewHolder();
            convertView= LayoutInflater.from(mContext).inflate(R.layout.list_item,parent,false);
            holder.mTextView= (TextView) convertView.findViewById(R.id.tv);
            convertView.setTag(holder);
        }else{
            holder= (ViewHolder) convertView.getTag();
        }
        String s = mList.get(position).getName();
        holder.mTextView.setText(s);
        return convertView;
    }
    private static class ViewHolder{
        TextView mTextView;
    }
}

public class Person {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

public class MainActivity extends AppCompatActivity {
    private ListView mListView;
    private List<Person> mList=new ArrayList<>();
    private ListAdapter mAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initData();
        setListener();
    }

    private void setListener() {
        mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                int firstVisiblePosition = mListView.getFirstVisiblePosition(); //屏幕内当前可以看见的第一条数据
                if(position-firstVisiblePosition>=0){
                    //1.获取当前点击的条目的view
                    View itemView = mListView.getChildAt(position - firstVisiblePosition);
                    //2.查找出相应的控件
                    TextView textView= (TextView) itemView.findViewById(R.id.tv);
                    //3.更新ui
                    textView.setText("我是更新后的数据"+position);
                    //4.更新数据源
                   mList.get(position).setName("我是更新后的数据"+position);
                }

            }
        });
    }

    private void initData() {
        Person person=null;
        for (int i = 0; i < 30; i++) {
            person=new Person();
            person.setName("条目"+i);
            mList.add(person);
        }
        mAdapter=new ListAdapter(mList);
        mListView.setAdapter(mAdapter);
    }

    private void initView() {
        mListView= (ListView) findViewById(R.id.lv);
    }
}

listView列表刷新某一条数据时采用notifyDataSetChanged()代价有点高，最好能 局部刷新 。局部刷新的 重点 是， 找到要更新的那项的View，然后再根据业务逻辑更新数据即可 。

大概就是3步：

1.找到要更新的那条数据的item 对于的view

因为listView条目的复用，所以当前点击的位置对应的条目为position- FirstVisiblePosition

2.获取该item中对于的相关View ，修改相关view显示的值

3.获取该item中对于的相关View ，修改相关view显示的值
举个例子：

public class ListAdapter extends BaseAdapter{
    private List<Person> mList;
    private Context mContext;
    private int count=0;

    public ListAdapter(List<Person> list) {
        mList = list;
    }

    @Override
    public int getCount() {
        return mList!=null?mList.size():0;
    }

    @Override
    public Object getItem(int position) {
        return mList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        count++;
        Log.d("getView被调用的次数===",count+"");
        mContext=parent.getContext();
        ViewHolder holder=null;
        if(convertView==null){
            holder=new ViewHolder();
            convertView= LayoutInflater.from(mContext).inflate(R.layout.list_item,parent,false);
            holder.mTextView= (TextView) convertView.findViewById(R.id.tv);
            convertView.setTag(holder);
        }else{
            holder= (ViewHolder) convertView.getTag();
        }
        String s = mList.get(position).getName();
        holder.mTextView.setText(s);
        return convertView;
    }
    private static class ViewHolder{
        TextView mTextView;
    }
}

public class Person {
    private String name;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }
}

public class MainActivity extends AppCompatActivity {
    private ListView mListView;
    private List<Person> mList=new ArrayList<>();
    private ListAdapter mAdapter;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
        initData();
        setListener();
    }

    private void setListener() {
        mListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                int firstVisiblePosition = mListView.getFirstVisiblePosition(); //屏幕内当前可以看见的第一条数据
                if(position-firstVisiblePosition>=0){
                    //1.获取当前点击的条目的view
                    View itemView = mListView.getChildAt(position - firstVisiblePosition);
                    //2.查找出相应的控件
                    TextView textView= (TextView) itemView.findViewById(R.id.tv);
                    //3.更新ui
                    textView.setText("我是更新后的数据"+position);
                    //4.更新数据源
                   mList.get(position).setName("我是更新后的数据"+position);
                }

            }
        });
    }

    private void initData() {
        Person person=null;
        for (int i = 0; i < 30; i++) {
            person=new Person();
            person.setName("条目"+i);
            mList.add(person);
        }
        mAdapter=new ListAdapter(mList);
        mListView.setAdapter(mAdapter);
    }

    private void initView() {
        mListView= (ListView) findViewById(R.id.lv);
    }
}