Question

大家好，我一直在尝试使用数据库并将其信息显示在listView中，但我无法使其正常工作。这是我的DatabaseHelper类（它从SQLiteOpenHelper扩展）：

FBSDKCoreKit.h
FBSDK_EXTERN NSString* const EMAIL;

这是我的ActivityMain：`

public static String DB_PATH = "/data/data/ice.tea09.sqlitedemo/databases/";

public static String DB_NAME = "Test.sqlite";

public static final int DB_VERSION = 1;

public static final String TB_USER = "Users";

private SQLiteDatabase myDB;
private Context context;

//private String DB_PATH =context.getFilesDir().getPath();

public DatabaseHelper(Context context)
{
    super(context, DB_NAME, null, DB_VERSION);  
    this.context = context;
}

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

}

@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
{
    // TODO Auto-generated method stub

}

@Override
public synchronized void close()
{
    if(myDB!=null)
    {
        myDB.close();
    }
    super.close();
}

public List<String> getAllUsers()
{
    List<String> listUsers = new ArrayList<String>();
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor c;

    try
    {
        c = db.rawQuery("SELECT * FROM " + TB_USER , null);
        if(c == null) return null;

        String name;
        c.moveToFirst();
        do
        {
            name = c.getString(1);
            listUsers.add(name);
        } while (c.moveToNext()); 
        c.close();
    }
    catch (Exception e)
    {
        Log.e("tle99", e.getMessage());
    }


    db.close();     

    return listUsers;
}


/*
 * Copy database from source code assets to device
 * @throws IOException
 */
public void copyDataBase() throws IOException
{
    try
    {
        InputStream myInput = context.getAssets().open(DB_NAME);
        String outputFileName = DB_PATH + DB_NAME;
        OutputStream myOutput = new FileOutputStream(outputFileName);

        byte[] buffer = new byte[1024];
        int length;

        while((length = myInput.read(buffer))>0)
        {
            myOutput.write(buffer, 0, length);
        }

        myOutput.flush();
        myOutput.close();
        myInput.close();
    }
    catch (Exception e)
    {
        Log.e("tle99 - copyDatabase", e.getMessage());
    }

}

/*
 * Check if the database doesn't exist on device, create new one
 * @throws IOException
 */
public void createDataBase() throws IOException
{
    boolean dbExist = checkDataBase();      

    if (dbExist)
    {

    }
    else
    {
        this.getReadableDatabase();
        try
        {
            copyDataBase();
        }
        catch (IOException e)
        {
            Log.e("tle99 - create", e.getMessage());
        }
    }
}

// ---------------------------------------------
// PRIVATE METHODS
// ---------------------------------------------

/*
 * Check if the database is exist on device or not
 * @return
 */
private boolean checkDataBase()
{
    SQLiteDatabase tempDB = null;
    try
    {
        String myPath = DB_PATH + DB_NAME;
        tempDB = SQLiteDatabase.openDatabase(myPath, null,
                SQLiteDatabase.OPEN_READWRITE);
    }
    catch (SQLiteException e)
    {
        Log.e("tle99 - check", e.getMessage());
    }
    if (tempDB != null)
    {
        tempDB.close();
    }

    return tempDB != null ? true : false;
}

我的资产文件夹中有一个数据库该应用程序在启动和运行时什么也没有显示谁能帮我这个忙，请问我真的不知道。

Answer 1

首先最好使用

获取数据库地址。

@SuppressLint("SdCardPath")
private void checkDBAddress(Context context) {
    if (android.os.Build.VERSION.SDK_INT >= 17) {
        DB_PATH = context.getApplicationInfo().dataDir + "/databases/";
    } else {
        DB_PATH = "/data/data/" + context.getPackageName() + "/databases/";
    }
}

在该行中，您应该从零开始，所以如果您只有一个字段，请更改它

name = c.getString(1);

到

name = c.getString(0);

最后，如果您遇到相同的问题，将适配器改为

，则我在ArrayAdapter上遇到了异常

ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, list);

在listView android应用中显示现有的SQLite数据库

1 个答案: