android listview getviewtypecount和getItemViewType

Posted 2020-07-28 奶霸000

package newdemo.jeno.listviewdemo;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Map;

public class TestAndroidActivity extends Activity {


    EditText msgContent;
    ListView listView;
    BaseAdapter adapter;
    ArrayList<Map<String, String>> data = new ArrayList<Map<String, String>>();

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        initViews();
    }

    private void initViews() {
        msgContent = (EditText) findViewById(R.id.content);
        Button btnSend = (Button) findViewById(R.id.send);
        btnSend.setOnClickListener(onClickListener);
        Button btnReceive = (Button) findViewById(R.id.receive);
        btnReceive.setOnClickListener(onClickListener);
        Button btnPic = (Button) findViewById(R.id.pic);
        btnPic.setOnClickListener(onClickListener);
        listView = (ListView) findViewById(R.id.list);
        adapter = new TestAdapter();
        listView.setAdapter(adapter);
    }

    private View.OnClickListener onClickListener = new View.OnClickListener() {

        public void onClick(View v) {
            Map<String, String> item;
            item = new HashMap<String, String>();
            switch (v.getId()) {
                case R.id.pic:
                    item.put("type", TYPE_PIC + "");
                    item.put("content", "图片");
                    break;
                case R.id.send:
                    item.put("type", TYPE_SEND + "");
                    item.put("content", "发送消息" + msgContent.getText().toString().trim());
                    break;
                case R.id.receive:

                    item.put("type", TYPE_RECEIVE + "");
                    item.put("content", "收到消息" + msgContent.getText().toString().trim());
                    break;
            }
            data.add(item);
            adapter.notifyDataSetChanged();
            msgContent.setText("");
        }
    };

    class TestAdapter extends BaseAdapter {

        public int getCount() {
            return data.size();
        }

        public Object getItem(int position) {
            if (position < getCount()) {
                return data.get(position);
            }
            return null;
        }

        public long getItemId(int position) {

            return 0;
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            System.out.println("getView::" + position);
            int type = TYPE_SEND;
            try {
                type = Integer.parseInt(data.get(position).get("type"));
            } catch (Exception e) {
                e.printStackTrace();
            }
            ViewHolder holder = null;
            if (convertView == null) {
                System.out.println("getView::convertView is null");
                holder = new ViewHolder();
                switch (type) {
                    case TYPE_SEND:
                        convertView = View.inflate(getBaseContext(),
                                R.layout.listitem_send, null);
                        holder.text = (TextView) convertView
                                .findViewById(R.id.message);
                        break;
                    case TYPE_RECEIVE:
                        convertView = View.inflate(getBaseContext(),
                                R.layout.listitem_receive, null);
                        holder.text = (TextView) convertView
                                .findViewById(R.id.message);
                        break;
                    case TYPE_PIC:
                        convertView = new ImageView(getBaseContext());
                        ((ImageView) convertView).setImageResource(R.drawable.icon);
                        break;
                }
                convertView.setTag(holder);
            } else {
                System.out.println("getView::convertView not null");
                holder = (ViewHolder) convertView.getTag();
            }

            if (type != TYPE_PIC) {
                String msg = data.get(position).get("content");
                holder.text.setText(msg);
            }
            return convertView;
        }

        public int getItemViewType(int position) {
            int type = super.getItemViewType(position);
            try {
                type = Integer.parseInt(data.get(position).get("type"));
            } catch (Exception e) {
                e.printStackTrace();
            }
            System.out.println("getItemViewType::" + position + " is " + type);
            return type;
        }

        public int getViewTypeCount() {
            System.out.println("getViewTypeCount is " + 3);
            return 3;
        }

        class ViewHolder {
            TextView text;
        }
    }

    /**
     * 发送的消息
     */
    private static final int TYPE_SEND = 0;
    /**
     * 收到的消息
     */
    private static final int TYPE_RECEIVE = TYPE_SEND + 1;
    /**
     * 图片
     */
    private static final int TYPE_PIC = TYPE_RECEIVE + 1;


}


一个项目说明问题
注意的是：
在

public int getItemViewType(int position) {
    int type = super.getItemViewType(position);
    try {
        type = Integer.parseInt(data.get(position).get("type"));
    } catch (Exception e) {
        e.printStackTrace();
    }
    System.out.println("getItemViewType::" + position + " is " + type);
    return type;

//次地方返回的类型一定要比下面的

getViewTypeCount的数值小   比如 下面的count返回的是3   怎这个地方最大是2   就是返回的是数组的角标

}

public int getViewTypeCount() {
    System.out.println("getViewTypeCount is " + 3);
    return 3;
}