ListView的适配器的问题

Question

package com.softeem.phone;

import android.database.Cursor;
import android.provider.ContactsContract;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.ListViewCompat;
import android.widget.ArrayAdapter;
import android.widget.ListView;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
private ListView list;
private ArrayList arrayList;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
list = (ListView) findViewById(R.id.list);
arrayList=new ArrayList<>();
list.setAdapter(new ArrayAdapter(this,android.R.layout.simple_list_item_1,arrayList));
readContacts(); //这里是先配置的适配器，再往arraylist中添加内容的。为啥还能正确显示数据（也就是说页面显示了readContacts()执行后的数据）刚开始
List中不应该是空的？然后页面上显示空才对呀 }

private void readContacts() {
    Cursor cur=null;
    try {
         cur = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null);
        int i=0;
        while(cur.moveToNext())
        {
            i++;
            if(i>7)
                break;
            String name = cur.getString(cur.getColumnIndex(ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME));
            arrayList.add(name);
        }
    } finally {
        if(cur!=null)
            cur.close();
    }

}

}

Answer 1

你调用list.setAdapte并把List数据传入后，你后面更新了List数据，Adapter也会去自动刷新的（观察者模式）。

但是最后调用下notifyDataSetChange方法去刷新数据