Android 从数据库中获取记录数并将其存储在整数中
我想以整数形式将数据库中的记录数输入我的应用程序,然后显示它。。。 我该怎么做 我不能这样做 这是数据库代码Android 从数据库中获取记录数并将其存储在整数中,android,database,count,Android,Database,Count,我想以整数形式将数据库中的记录数输入我的应用程序,然后显示它。。。 我该怎么做 我不能这样做 这是数据库代码 public int counttable() { int count=0; openOrCreateDatabase(); count=db.execSQL("select count(*) from "+TableNameis+";"); return count; } 我知道数据类型不匹配…谁能建议我怎么做?? 如何将计数值存储在整数变量中
public int counttable()
{
int count=0;
openOrCreateDatabase();
count=db.execSQL("select count(*) from "+TableNameis+";");
return count;
}
我知道数据类型不匹配…谁能建议我怎么做??
如何将计数值存储在整数变量中
Dashboard.java
public class Dashboard extends Activity {
EditText edt_pending, edt_completed,edt_synched;
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.dashboard);
edt_pending=(EditText)findViewById(R.id.editpending);
edt_completed=(EditText)findViewById(R.id.editcompleted);
edt_synched=(EditText)findViewById(R.id.editsynched);
WayDataBase way=new WayDataBase(Dashboard.this);
int count=way.counttable();
edt_completed.setText(count);
}
}
logcat
04-08 07:15:02.216:E/AndroidRuntime(16026):java.lang.RuntimeException:无法启动活动组件信息{com.android.lthomepage/com.android.lthomepage.Dashboard}:android.content.res.Resources$NotFoundException:字符串资源ID#0x1
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.ActivityThread.access$600(ActivityThread.java:141)
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.os.Handler.dispatchMessage(Handler.java:99)上
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.os.Looper.loop(Looper.java:137)
04-08 07:15:02.216:E/AndroidRuntime(16026):位于android.app.ActivityThread.main(ActivityThread.java:5039)
04-08 07:15:02.216:E/AndroidRuntime(16026):位于java.lang.reflect.Method.Invokenactive(本机方法)
04-08 07:15:02.216:E/AndroidRuntime(16026):在java.lang.reflect.Method.invoke(Method.java:511)
04-08 07:15:02.216:E/AndroidRuntime(16026):在com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
04-08 07:15:02.216:E/AndroidRuntime(16026):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
04-08 07:15:02.216:E/AndroidRuntime(16026):在dalvik.system.NativeStart.main(本机方法)
04-08 07:15:02.216:E/AndroidRuntime(16026):由以下原因引起:android.content.res.Resources$NotFoundException:字符串资源ID#0x1
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.content.res.Resources.getText(Resources.java:230)
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.widget.TextView.setText(TextView.java:3640)
04-08 07:15:02.216:E/AndroidRuntime(16026):在com.android.lthomepage.Dashboard.onCreate(Dashboard.java:27)
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.Activity.performCreate(Activity.java:5104)上
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)上
04-08 07:15:02.216:E/AndroidRuntime(16026):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
您可以使用获取记录数的计数
public int counttable()
{
int count=0;
openOrCreateDatabase();
// count=db.execSQL("select * from "+TableNameis+";"); - This statement is invalid
// Use this instead
count=db.rawQuery(selectionQuery, null).getCount();
return count;
}
请尝试以下代码:
public int counttable()
{
int count=0;
openOrCreateDatabase();
Cursor c = db.rawQuery("select * from your_table_name",null);
count=c.getCount();
return count;
}
而且
使用SELECT查询就足够了,然后计算光标的大小
EditText edt_pending, edt_completed,edt_synched;
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.dashboard);
edt_pending=(EditText)findViewById(R.id.editpending);
edt_completed=(EditText)findViewById(R.id.editcompleted);
edt_synched=(EditText)findViewById(R.id.editsynched);
way= new WayDataBase(this);
try
{
way.createDatabase();
} catch (IOException ioe)
{
throw new Error("Unable to create database");
}
int count=way.counttable();
edt_completed.setText(count+"");
}
}不幸的是,应用程序已停止..对我的数据库函数的调用是
WayDataBase way=newwaydatabase(getApplicationContext());int count=way.counttable()代码>…我做错什么了吗???因为logcat中的错误是资源找不到异常04-08 07:15:02.216:E/AndroidRuntime(16026):java.lang.RuntimeException:无法启动活动组件信息{com.android.lthomepage/com.android.lthomepage.Dashboard}:android.content.res.Resources$NotFoundException:String resource ID#0x1在Dashboard类中,所有数据库访问都在onCreate函数中…是否因为存在强制关闭?共享代码和日志错误。如果没有您的codetry edt_completed.setText(String.valueOf(count)),我无法理解错误;你必须填上你的桌子名
private static String DATABASE_NAME = "Database Name";
private SQLiteDatabase myDataBase;
private Context myContext;
private String DATABASE_PATH = "/data/data/"Package Name"/databases/";
// Constructor
public WayDataBase (Context context)
{
super(context, DATABASE_NAME, null, 1);
this.myContext = context;
}
// Create DataBase
public void createDatabase() throws IOException
{
boolean dbExist = checkDataBase();
if(dbExist)
{
}
else
{
this.getReadableDatabase();
try
{
this.close();
copyDataBase();
}
catch (IOException e)
{
throw new Error("Error copying database");
}
}
}
// check Database Existing or not
private boolean checkDataBase()
{
SQLiteDatabase checkDB = null;
try
{
String myPath = DATABASE_PATH + DATABASE_NAME;
checkDB = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
catch(SQLiteException e)
{
}
if(checkDB != null)
{
checkDB.close();
}
return checkDB != null ? true : false;
}
// Copy DataBase from assets to SD card
private void copyDataBase() throws IOException
{
String outFileName = DATABASE_PATH + DATABASE_NAME;
OutputStream myOutput = new FileOutputStream(outFileName);
InputStream myInput = myContext.getAssets().open(DATABASE_NAME);
byte[] buffer = new byte[1024];
int length;
while ((length = myInput.read(buffer)) > 0)
{
myOutput.write(buffer, 0, length);
}
myInput.close();
myOutput.flush();
myOutput.close();
}
// Open DataBase
public void openDatabase() throws SQLException
{
String myPath = DATABASE_PATH + DATABASE_NAME;
myDataBase = SQLiteDatabase.openDatabase(myPath, null, SQLiteDatabase.OPEN_READWRITE);
}
public int counttable()
{
int count=0;
openDatabase();
Cursor c = myDataBase.rawQuery("SELECT * FROM table_name",null);
return count;
}
EditText edt_pending, edt_completed,edt_synched;
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.dashboard);
edt_pending=(EditText)findViewById(R.id.editpending);
edt_completed=(EditText)findViewById(R.id.editcompleted);
edt_synched=(EditText)findViewById(R.id.editsynched);
way= new WayDataBase(this);
try
{
way.createDatabase();
} catch (IOException ioe)
{
throw new Error("Unable to create database");
}
int count=way.counttable();
edt_completed.setText(count+"");
}