ListView的刷新

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/TopWilling/article/details/52856571

1.整体刷新

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        final ListView listView = (ListView) findViewById(R.id.list_view);


        final List<Message> messageList = new ArrayList<>(100);
        for (int i = 0; i < 100; i++) {
            String time = Calendar.getInstance().getTime().toLocaleString();
            messageList.add(new Message(
                    R.drawable.icon_contact,
                    "好友" + i,
                    "我是文本消息" + i,
                    time));
        }


        final BaseAdapter adapter = new MessageAdapter(this, messageList);
        listView.setAdapter(adapter);


       findViewById(R.id.add_message).setOnClickListener(new View.OnClickListener() {
           @Override
           public void onClick(View v) {
               String time = Calendar.getInstance().getTime().toLocaleString();
               messageList.add(0, new Message(
                        R.drawable.icon_contact,
                      "好友",
                       "我是文本消息",
                        time));
              adapter.notifyDataSetChanged();
           }
        });


        findViewById(R.id.remove_message).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (messageList.size() > 0) {
                    messageList.remove(0);
                    adapter.notifyDataSetChanged();
                }
            }
        });
    }
}

部分刷新，有些数据只是listview的某个item的数据发生了变化，这个时候并不需要整体刷新，只需要改变对应的item的数据：

public class MainActivity extends AppCompatActivity {
    private ListView listView;
    private List<Message> datas;
    private EditText modifyPosition;
    private View modifyButton;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        listView = (ListView) findViewById(R.id.list_view);

        datas = new ArrayList<>(100);
        for (int i = 0; i < 100; i++) {
            String time = Calendar.getInstance().getTime().toLocaleString();
            datas.add(new Message(
                    R.drawable.icon_contact,
                    "好友" + i,
                    "我是文本消息" + i,
                    time));
        }

        ListAdapter adapter = new MessageAdapter(this, datas);
        listView.setAdapter(adapter);

        modifyPosition = (EditText) findViewById(R.id.modify_position);
        modifyButton = findViewById(R.id.modify_message);

        modifyButton.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                try {
                    int position = Integer.parseInt(modifyPosition.getText().toString());

                    Message message = datas.get(position);
                    message.setContent("这是修改后的消息" + position);//这只是把数据设置好，但是并没有刷新显示界面！

                    partialRefresh(listView, position);//刷新数据
                } catch (NumberFormatException e) {
                    e.printStackTrace();
                    Toast.makeText(MainActivity.this, "输入不合法", Toast.LENGTH_SHORT).show();
                }
            }
        });
    }

    private void partialRefresh(ListView listView, int position) {
        if (position >= listView.getFirstVisiblePosition()
                && position <= listView.getLastVisiblePosition()) {
            int childIndex = position - listView.getFirstVisiblePosition();
            Toast.makeText(getApplicationContext(),childIndex+"",Toast.LENGTH_LONG).show();
            View child = listView.getChildAt(childIndex);

            if (child.getTag() instanceof ViewHolder) {
                //child.getTag() 是一个viewholder，在viewholder中有一个刷新方法，把传入的内容填充进对应的控件
                ((ViewHolder) child.getTag()).refreshContent(datas.get(position).getContent());
//                ((ViewHolder) child.getTag()).refreshContent(datas.get(position).getContent());
            }
        }
    }
}

viewholder 

public class MessageAdapter extends BaseAdapter {
    private List<Message> messageList;
    private LayoutInflater layoutInflater;

    public MessageAdapter(Context context, List<Message> messageList) {
        this.layoutInflater = LayoutInflater.from(context);
        this.messageList = messageList;
    }


    @Override
    public int getCount() {
        return messageList.size();
    }

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

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ViewHolder viewHolder;

        if (convertView == null) {
            convertView = layoutInflater.inflate(R.layout.text_message_item, parent, false);

            TextView time = (TextView) convertView.findViewById(R.id.message_time);
            TextView name = (TextView) convertView.findViewById(R.id.message_name);
            ImageView head = (ImageView) convertView.findViewById(R.id.message_head);
            TextView content = (TextView) convertView.findViewById(R.id.message_content);

            viewHolder = new ViewHolder(time, name, head, content);
            convertView.setTag(viewHolder);
        } else {
            viewHolder = (ViewHolder) convertView.getTag();
        }

        Message message = messageList.get(position);

        viewHolder.getTime().setText(message.getTime());
        viewHolder.getName().setText(message.getName());
        viewHolder.getHead().setImageResource(message.getHeadImageResId());
        viewHolder.getContent().setText(message.getContent());

        return convertView;
    }

    public static class ViewHolder {
        private TextView time;
        private TextView name;
        private ImageView head;
        private TextView content;

        public ViewHolder(
                TextView time,
                TextView name,
                ImageView head,
                TextView content) {
            this.time = time;
            this.name = name;
            this.head = head;
            this.content = content;
        }

        public TextView getTime() {
            return time;
        }

        public TextView getName() {
            return name;
        }

        public ImageView getHead() {
            return head;
        }

        public TextView getContent() {
            return content;
        }

        public void refreshContent(String content) {
            this.content.setText(content);
        }
    }
}