检索数据表单数据库后列表视图不更新

Posted 2023-04-19

【中文标题】检索数据表单数据库后列表视图不更新

【英文标题】：listview doesn't update after retrieving data form database

【发布时间】：2015-12-17 04:53:16

【问题描述】：

我想制作一个程序，从联系人列表中读取数据并将它们添加到数据库中，然后更新包含所选数据的列表视图。但是每次我单击添加按钮并打开联系人列表并选择一项时，列表视图都不会改变。我也不知道数据库存储在哪里。 主要活动：

public class BlockActivity extends Activity 
ArrayList<String> contactnumber= new ArrayList<String>();
ArrayList<String> contactname= new ArrayList<String>();
public static SQLiteDatabase database;
SQLiteDatabase myDB= null;
CustomAdapter adapter;



public void onCreate(Bundle savedInstanceState) 

    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Button pickContact = (Button) findViewById(R.id.button1);

pickContact.setOnClickListener(new OnClickListener() 


@Override
public void onClick(View v) 
    // user BoD suggests using Intent.ACTION_PICK instead of .ACTION_GET_CONTENT to avoid the chooser
    Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
    // BoD con't: CONTENT_TYPE instead of CONTENT_ITEM_TYPE
    intent.setType(ContactsContract.CommonDataKinds.Phone.CONTENT_ITEM_TYPE);
    startActivityForResult(intent, 1);  


);

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) 

    if (data != null) 
        Uri uri = data.getData();

        if (uri != null) 

            Cursor c = null;
            try 
                c = getContentResolver().query(uri, new String[] 
                            ContactsContract.CommonDataKinds.Phone.NUMBER,  
                             ContactsContract.CommonDataKinds.Phone.DISPLAY_NAME,
                        null, null, null);


                if (c != null && c.moveToFirst()) 
                    Log.i("error", "salalalalal");

                    String number = c.getString(0);

                    String name = c.getString(1);


                     manageDatabase(name, number);
                                        
             finally 
                if (c != null) 
                    c.close();
                
            
        
    


public void manageDatabase(String name, String number) 

    String TableName = "contact";


    /* Create a Database. */
    try 
     myDB = this.openOrCreateDatabase("DatabaseName", MODE_PRIVATE, null);

     /* Create a Table in the Database. */
     myDB.execSQL("CREATE TABLE IF NOT EXISTS "
       + TableName
       + " (" +
       "name TEXT, " +
       "number TEXT" +
           ");"
       );

     /* Insert data to a Table*/
     myDB.execSQL("INSERT INTO "
       + TableName
       + "(name,number)"
       + " VALUES ('name','number');");

    // retrieve data from database
     Cursor c = myDB.rawQuery("SELECT * FROM " + TableName , null);


     // Check if our result was valid.
     c.moveToFirst();


     if(c.moveToNext())
         while(!c.isAfterLast())
            
             Log.i("error",c.getString(0));
             Log.i("error",c.getString(1) ); 
         contactname.add(c.getString(0));
         contactnumber.add(c.getString(1));

         c.moveToNext();
         



      //fill the list view with results from database

      ListView lv=(ListView) findViewById(R.id.listView1);

       adapter = new CustomAdapter(this, contactname, contactnumber);
     lv.setAdapter(adapter);





    
    catch(Exception e) 
     Log.e("Error", "Error", e);
     finally 
     if (myDB != null)
      myDB.close();
    

这是自定义适配器：

public class CustomAdapter extends ArrayAdapter<String> 


private final Activity context;
private final ArrayList<String> nameList;
private final ArrayList<String> phoneList;
public CustomAdapter(Activity context,ArrayList<String> nameList, ArrayList<String> phoneList) 
        super(context, R.layout.detail, nameList);
        this.context = context;
        this.nameList = nameList;
        this.phoneList =phoneList;


        

@Override
public View getView(int position, View view, ViewGroup parent) 
LayoutInflater inflater = context.getLayoutInflater();
View rowView= inflater.inflate(R.layout.detail, null, true);
TextView word1 = (TextView) rowView.findViewById(R.id.one);
TextView word2 = (TextView) rowView.findViewById(R.id.two);

 word1.setText(nameList.get(position));
 word2.setText(phoneList.get(position));

return rowView;
  

main.xml 文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:orientation="vertical" >

<Button
    android:id="@+id/button1"
    android:layout_
    android:layout_
    android:text="add" />

<ListView
    android:id="@+id/listView1"
    android:layout_
    android:layout_ >
</ListView>

detail.xml 文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_
android:layout_
android:orientation="vertical" >


<LinearLayout
    android:layout_
    android:layout_
    android:layout_weight="1" >

    <TextView
        android:id="@+id/one"
        android:layout_
        android:layout_
        android:layout_weight="1"
        android:gravity="center"
        android:text="name"
        android:textSize="30dip" />

    <TextView
        android:id="@+id/two"
        android:layout_
        android:layout_
        android:layout_weight="1"
        android:gravity="center"
        android:text="name"
        android:textSize="30dip" />
</LinearLayout>

<Button
    android:id="@+id/button1"
    android:layout_
    android:layout_ android:background="#ff7f7f"/>

【参考方案1】：

要更新 View 中的数据，你应该调用他的适配器。

((ArrayAdapter) mMyListView.getAdapter()).notifyDataSetChanged(); 

【讨论】：

我应该在哪里使用它？

数据下载后。我在您的代码中找不到这一点。

我不下载数据库。它只使用查询。

那我不明白你的问题。什么时候升级到 View？

列表视图更新错误。此行contactname.add(c.getString(0));只给第一行。 c.moveToNext();没有任何效果。

【参考方案2】：

如果数据不稳定，请使用 RecyclerView！