Question

我正在努力学习SQLite。我想将数据库中的信息（TextView）放到可点击的ListView（我仍然无法点击ListView）。我可以获得一些关于如何从我的数据库获取数据并将其放在可点击的ListView上的帮助吗？以下是我希望在ListView中使用的教程网站中的代码：

Button ViewBack;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub

    super.onCreate(savedInstanceState);
    setContentView(R.layout.sqlview);

    ViewBack=(Button) findViewById(R.id.bVBack);
    TextView tv = (TextView) findViewById(R.id.tvSQLinfo);
    ViewBack.setOnClickListener(this);

    HotOrNot info = new HotOrNot(this);
    info.open();
    String data = info.geData(); 
    info.close();
    tv.setText(data);

}
@Override
public void onClick(View v) {
    // TODO Auto-generated method stub
    finish();

}

sqlview.xml：

<ScrollView
      android:layout_width="fill_parent"
      android:layout_height="match_parent" >      
<TextView
    android:id="@+id/tvSQLinfo"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_marginTop="10dp"
    android:text="get info from db" />
</ScrollView>

起初我试过这个：

ListView lv = (ListView) findViewById(R.id.listMe);
ListAdapter listAD = new ListAdapter(this,R.id.listMe, tv);
 lv.setAdapter(listAD);

但是我收到的错误无法实例化数据类型ListAdapter，因此我尝试替换SimpleCursorAdapter上的new ListAdapter(this,R.id.listMe,tv)：

ListAdapter listAD = new SimpleCursorAdapter (this,R.id.listMe,tv, null, null);

但是它再次给了我一个错误，它建议我将演员阵容更改为Cursor所以，我改变了所有内容，直到它没有给我任何错误。当我试图运行它时，它将无法正常工作。这是HotOrNotClass：

public static final String KEY_ROWID= "_id"; 
public static final String KEY_NAME= "persons_name"; 
public static final String KEY_HOTNESS= "presons_hotness"; 

private static final String DATABASE_NAME= "HotOrNotdb";
public static final String DATABASE_TABLE= "peopleTable"; 
private static final int DATABASE_VERSION= 1;

private DbHelper ourHelper;
private final Context ourContext;
private SQLiteDatabase ourDatabase;

private static class DbHelper extends SQLiteOpenHelper{

    public DbHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
        // TODO Auto-generated constructor stub
    }


    @Override
    public void onCreate(SQLiteDatabase db) {
        // TODO Auto-generated method stub

        db.execSQL("CREATE TABLE " + DATABASE_TABLE + " (" +
                KEY_ROWID + " INTEGER PRIMARY KEY AUTOINCREMENT, " +
                KEY_NAME + " TEXT NOT NULL, " +
                KEY_HOTNESS + " TEXT NOT NULL);"
        );  

    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // TODO Auto-generated method stub
            db.execSQL("DROP TABLE IF EXISTS " +DATABASE_TABLE);
            onCreate(db);
    }

}
public HotOrNot(Context c){
    ourContext=c;
}

public HotOrNot open() throws SQLiteException{
ourHelper = new DbHelper(ourContext);
ourDatabase =ourHelper.getWritableDatabase();

return this;  }

public void close(){
    ourHelper.close();
}

public long createEntry(String name, String hotness) {
    // TODO Auto-generated method stub
    ContentValues cv = new ContentValues();
    cv.put(KEY_NAME, name);
    cv.put(KEY_HOTNESS, hotness);
    return ourDatabase.insert(DATABASE_TABLE, null, cv);

}

public String geData() {
    // TODO Auto-generated method stub
    String[]columns=new String[]{ KEY_ROWID,KEY_NAME, KEY_HOTNESS};
    Cursor c =ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    String result ="";
    int iRow=c.getColumnIndex(KEY_ROWID);
    int iName=c.getColumnIndex(KEY_NAME);
    int iHotness=c.getColumnIndex(KEY_HOTNESS);

    for(c.moveToFirst(); !c.isAfterLast();c.moveToNext()){
        result=result + c.getString(iRow)+" "+c.getString(iName)+" "+c.getString(iHotness)+"\n";
    }
    return result;

}
public String getName(long l) throws SQLiteException{
    // TODO Auto-generated method stub
    String[]columns=new String[]{ KEY_ROWID,KEY_NAME, KEY_HOTNESS};
    Cursor c= ourDatabase.query(DATABASE_TABLE, columns,  KEY_ROWID+"="+l, null, null, null, null);
    if (c!=null){
        c.moveToFirst();

        String name=c.getString(1);
        return name;
    }
    return null;
}

public String getHotness(long l)throws SQLiteException {
    // TODO Auto-generated method stub
    String[]columns=new String[]{ KEY_ROWID,KEY_NAME, KEY_HOTNESS};
    Cursor c= ourDatabase.query(DATABASE_TABLE, columns, KEY_ROWID+"="+l, null, null, null, null);
    if (c!=null){
        c.moveToFirst();

        String hotness=c.getString(2);
        return hotness;
    }
    return null;
}

Answer 1

您的getData()方法会返回一个包含所有结果的大String。我不认为这是你想要的列表，所以修改getData（）方法，这样你就可以返回代表你的数据库记录的String列表：

public ArrayList<String> geData() {
    // TODO Auto-generated method stub
    String[]columns=new String[]{ KEY_ROWID,KEY_NAME, KEY_HOTNESS};
    Cursor c =ourDatabase.query(DATABASE_TABLE, columns, null, null, null, null, null);
    ArrayList<String> result = new ArrayList<String>();
    int iRow=c.getColumnIndex(KEY_ROWID);
    int iName=c.getColumnIndex(KEY_NAME);
    int iHotness=c.getColumnIndex(KEY_HOTNESS);

    for(c.moveToFirst(); !c.isAfterLast();c.moveToNext()){
        result.add(c.getString(iRow)+" "+c.getString(iName)+" "+c.getString(iHotness));
    }
    return result;
}

为了显示列表，您必须在ListView布局（Activity）中添加sqlview元素，这样您就可以制作如下布局：

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

    <Button
        android:id="@+id/bVBack"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Something" />

    <ListView
        android:id="@+id/listMe"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

然后在您的onCreate()方法中将ListView绑定到Adapter：

//...
ListView lv = (ListView) findViewById(R.id.listMe);
HotOrNot info = new HotOrNot(this);
info.open();
ArrayList<String> data = info.geData(); 
info.close();
lv.setAdapter(new ArrayAdapter<String>(this, android.R.layout.simple_list_item1, data));

如何从我的数据库中获取数据并将其放在可点击的ListView上？

1 个答案: