Android Question javaObject getMetaData exception

Patrick Clark · Jun 4, 2020

I have taken a bit of the jRDC2 code from the b4J library and implemented it in my SQL handler.

The code is the stuff that converts a sql ResultSet to a DBResult Type

The DBResult Type is

B4X:

    Type DBResult ( _
        Columns As Map, _
        Rows As List, _
        Cursor As Int, _
        NoRows As Int)

The code is below.

This all works fine in B4J but when I try and use it in B4A I get an exception at line 3

B4X:

Dim rsmd As JavaObject = jrs.RunMethod("getMetaData", Null)

The exception is:
java.lang.RuntimeException: Method: getMetaData not found in: android.database.sqlite.SQLiteCursor
The caught exception (Try/Catch) is (RuntimeException) java.lang.RuntimeException: Method: getMetaData not found in: android.database.sqlite.SQLiteCursor
The full log is at the end of this post.

Can anybody help me understand what is going wrong?

Thanks

B4X:

Private Sub rs2DBResult(rs As ResultSet) As DBResult
    Dim limit As Double = 10000
    Dim jrs As JavaObject = rs
    Dim rsmd As JavaObject = jrs.RunMethod("getMetaData", Null)
    Dim cols As Int = rs.ColumnCount
    Dim res As DBResult
    res.Initialize
    res.columns.Initialize
'    res.Tag = Null 'without this the Tag properly will not be serializable.
    For i = 0 To cols - 1
        res.columns.Put(i,rs.GetColumnName(i).ToLowerCase)
    Next
    res.Rows.Initialize
    Do While rs.NextRow And limit > 0
        Dim row(cols) As Object
        For i = 0 To cols - 1
            Dim ct As Int = rsmd.RunMethod("getColumnType", Array(i + 1))
            'check whether it is a blob field
            If ct = -2 Or ct = 2004 Or ct = -3 Or ct = -4 Then
                row(i) = rs.GetBlob2(i)
            Else if ct = 2 Or ct = 3 Then
                row(i) = rs.GetDouble2(i)
            Else If DateTimeMethods.ContainsKey(ct) Then
                Dim SQLTime As JavaObject = jrs.RunMethodJO(DateTimeMethods.Get(ct), Array(i + 1))
                If SQLTime.IsInitialized Then
                    row(i) = SQLTime.RunMethod("getTime", Null)
                Else
                    row(i) = Null
                End If
            Else
                row(i) = jrs.RunMethod("getObject", Array(i + 1))
            End If
        Next
        res.Rows.Add(row)
    Loop
    res.Cursor = 0
    res.NoRows = res.Columns.Size
    Return res
End Sub

Full Exception Log:

Rich (BB code):

java.lang.RuntimeException: Method: getMetaData not found in: android.database.sqlite.SQLiteCursor
    at anywheresoftware.b4j.object.JavaObject$MethodCache.getMethod(JavaObject.java:366)
    at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:119)
    at b4a.example.sqle._rs2dbresult(sqle.java:480)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:732)
    at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:348)
    at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:255)
    at java.lang.reflect.Method.invoke(Native Method)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:176)
    at anywheresoftware.b4a.shell.DebugResumableSub$RemoteResumableSub.resume(DebugResumableSub.java:22)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:250)
    at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:137)
    at anywheresoftware.b4a.BA$2.run(BA.java:370)
    at android.os.Handler.handleCallback(Handler.java:883)
    at android.os.Handler.dispatchMessage(Handler.java:100)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7709)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:516)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:950)

OliverA · Jun 4, 2020

Patrick Clark said:
Can anybody help me understand what is going wrong?

Android's ResultSet does not support all functionality of Java's ResultSet. The only workaround that I can think of is to try to use the JdbcSQL library on Android (it's a port of B4J's jSQL library). Then use that libraries SQL object and the InitializeSQLite method to open your SQLite database. You should then be able to use the getMetaData method of the underlying ResultSet Java object. I did not realize you would try to use this on Android when you requested a solution to your problem here: https://www.b4x.com/android/forum/threads/sending-resultset-over-network-connection.118501/.

Note: Please change the title. This has nothing to do with jRDC2 itself. jRDC2 is designed to run under systems that are supported by B4J, not B4A.

Link to JdbcSQL: https://www.b4x.com/android/forum/t...ly-connect-to-remote-databases.84016/#content

Patrick Clark · Jun 4, 2020

OliverA said:
Android's ResultSet does not support all functionality of Java's ResultSet. The only workaround that I can think of is to try to use the JdbcSQL library on Android (it's a port of B4J's jSQL library). Then use that libraries SQL object and the InitializeSQLite method to open your SQLite database. You should then be able to use the getMetaData method of the underlying ResultSet Java object. I did not realize you would try to use this on Android when you requested a solution to your problem here: https://www.b4x.com/android/forum/threads/sending-resultset-over-network-connection.118501/.

Note: Please change the title. This has nothing to do with jRDC2 itself. jRDC2 is designed to run under systems that are supported by B4J, not B4A.

Link to JdbcSQL: https://www.b4x.com/android/forum/t...ly-connect-to-remote-databases.84016/#content

Thanks I thought that might be the case.

I have looked at jdbcSQL but I don't want remote access to the database.

Is the source available?

OliverA · Jun 4, 2020

Patrick Clark said:
but I don't want remote access to the database.

You don’t remote access SQLite with JdbcSQL. It opens local SQLite only

Patrick Clark · Jun 4, 2020

Then I don't understand this in the example code

B4X:

    Private jdbcUrl As String = "jdbc:mysql://192.168.0.6/test"
    Private Username As String = "username"
    Private Password As String = "password"

OliverA · Jun 4, 2020

Patrick Clark said:
Then I don't understand this in the example code

That's for the Initialize2 method of the JdbcSQL SQL object. Do something like

Code:

Dim SQL1 As JdbcSQL
SQL1.InitializeSQLite(File.DirApp, "MyDb.db", True)

JdbcSQL's InitializeSQLite method is the same as B4A's standard Initialize method

MicroDrie · Jun 4, 2020

Silly question of me ?:

Code:
This all works fine in B4J but when I try and use it in B4A I get an exception at line 3

Code:

Dim rsmd As JavaObject = jrs.RunMethod("getMetaData", Null)

The exception is:
java.lang.RuntimeException: Method: getMetaData not found in: android.database.sqlite.SQLiteCursor

The RunMethod is points to a Java routine 'getMetaData', which is not included in the given source.
I wonder ? : does B4A say that the Java code is not present in your program (like in your given code in your post ?), or is there an error in the java code itself because the java code doesn't return an object?
By the way, debugging 'RunMethod' is a hard job. Mostly I add BA.Log("Step x"); to see what goes good.

Patrick Clark · Jun 4, 2020

Ok thanks, I'll give it a try.

Do you know if the source is available?

MicroDrie said:
Silly question of me ?:

The RunMethod is points to a Java routine 'getMetaData', which is not included in the given source.
I wonder ? : does B4A say that the Java code is not present in your program (like in your given code in your post ?), or is there an error in the java code itself because the java code doesn't return an object?
By the way, debugging 'RunMethod' is a hard job. Mostly I add BA.Log("Step x"); to see what goes good.

Hi

No everything is present, all libraries loaded. OliverA has pointed out that Android ResultSet doesn't support full functionality so all is fine with B4J but not with B4A

Patrick Clark · Jun 4, 2020

OliverA said:
That's for the Initialize2 method of the JdbcSQL SQL object. Do something like

Code:

Dim SQL1 As JdbcSQL SQL1.InitializeSQLite(File.DirApp, "MyDb.db", True)

JdbcSQL's InitializeSQLite method is the same as B4A's standard Initialize method

I am getting an error saying can't find "libsqlitejdbc.so" or at least that's what I think it's telling me, when i try to initializeSQLLite

Rich (BB code):

java.lang.UnsatisfiedLinkError: dalvik.system.PathClassLoader[DexPathList[[zip file "/data/app/b4a.example-v0U-Lsrfwxi_KKcpIcGAww==/base.apk"],nativeLibraryDirectories=[/data/app/b4a.example-v0U-Lsrfwxi_KKcpIcGAww==/lib/arm64, /system/lib64, /product/lib64]]] couldn't find "libsqlitejdbc.so"

B4X:

#Region  Activity Attributes
    #FullScreen: False
    #IncludeTitle: True
    #AdditionalJar: sqlite-jdbc-3.7.2
#End Region

Sub Process_Globals
End Sub

Sub Globals
End Sub

Sub Activity_Create(FirstTime As Boolean)

    Dim s As JdbcSQL
    Dim rs As JdbcResultSet
    Dim rp As RuntimePermissions
    Dim dir As String = rp.GetSafeDirDefaultExternal("")
    
    s.InitializeSQLite(dir, "MQTTServer.db", False)
    rs = s.ExecQuery("select * from TestData")
    Log(rs.ColumnCount)   

End Sub

OliverA · Jun 4, 2020

Patrick Clark said:
I am getting an error saying can't find "libsqlitejdbc.so" or at least that's what I think it's telling me, when i try to initializeSQLLite

I'm running into the same issue and this may be a dead end (unless someone else comes up with a work around to this). On the Android side, you may have to use
PRAGMA table_info to retrieve the column types. See: https://www.sqlite.org/pragma.html

Link:

Android UnsatisfiedLinkError · Issue #248 · xerial/sqlite-jdbc

Device: samsung s5 with android 6.0.0, api23, with permissions granted Here's the dependency parts of the gradle build file dependencies { compile 'com.android.support:support-v4:23+' compile 'com....

github.com

Patrick Clark · Jun 4, 2020

OliverA said:
I'm running into the same issue and this may be a dead end (unless someone else comes up with a work around to this). On the Android side, you may have to use
PRAGMA table_info to retrieve the column types. See: https://www.sqlite.org/pragma.html

Woah, that is way over my head

Patrick Clark · Jun 7, 2020

@OliverA

Hi

As you had helped so much I thought I would let you know I have it sorted.

It is a bit convoluted but I now have a portable SQL wrapper that works on both Android and Windows and results can be passed over the nework

What I ended up doing was creating a temporary view from the query rather that actually executing it

Then run "PRAGMA table_info (viewname)" into a resultset.

Then use this information to determine the Types of each column.

Finally I am able to build a DBResult from the temporary view which I then drop.

Just though you might like to know

peacemaker · Dec 22, 2022

Patrick Clark said:
@OliverA

Hi

As you had helped so much I thought I would let you know I have it sorted.

It is a bit convoluted but I now have a portable SQL wrapper that works on both Android and Windows and results can be passed over the nework

What I ended up doing was creating a temporary view from the query rather that actually executing it

Then run "PRAGMA table_info (viewname)" into a resultset.

Then use this information to determine the Types of each column.

Finally I am able to build a DBResult from the temporary view which I then drop.

Just though you might like to know

But why no any code example ? Please, share

Android Question javaObject getMetaData exception

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Android UnsatisfiedLinkError · Issue #248 · xerial/sqlite-jdbc

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