Hi everyone, i'm trying to understand how to use the RandomAccessFile Library, beacuse i need to store custom Types of data.
I'm always getting an error while reading, i'm confused.
The test code:
The error:
I'm always getting an error while reading, i'm confused.
The test code:
B4X:
Sub Globals
'These global variables will be redeclared each time the activity is created.
'These variables can only be accessed from this module.
Type Mex(Text As String, Owner As String)
End Sub
Sub Activity_Create(FirstTime As Boolean)
'Do not forget to load the layout file created with the visual designer. For example:
'Activity.LoadLayout("Layout1")
Dim m As Mex
m.Initialize
m.Owner = "Fred"
m.Text = "Hi"
Log("Mex1: " & m)
Dim rf As RandomAccessFile
rf.Initialize(File.DirInternal, "mex2.dat", False)
rf.WriteB4XObject(m, rf.CurrentPosition)
rf.Close
Dim rf2 As RandomAccessFile
rf2.Initialize(File.DirInternal, "mex2.dat", False)
Dim m2 As Mex = rf2.ReadB4XObject(rf.CurrentPosition)
Log("Mex2: " & m2)
rf2.Close
End SubThe error:
Error occurred on line: 45 (Main)
java.nio.BufferUnderflowException
at java.nio.DirectByteBuffer.getInt(DirectByteBuffer.java:230)
at anywheresoftware.b4a.randomaccessfile.RandomAccessFile.ReadInt(RandomAccessFile.java:137)
at anywheresoftware.b4a.randomaccessfile.RandomAccessFile.ReadB4XObject(RandomAccessFile.java:319)
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 b4a.example.main.afterFirstLayout(main.java:104)
at b4a.example.main.access$000(main.java:17)
at b4a.example.main$WaitForLayout.run(main.java:82)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:6020)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:936)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:797)
** Activity (main) Resume **
java.nio.BufferUnderflowException
at java.nio.DirectByteBuffer.getInt(DirectByteBuffer.java:230)
at anywheresoftware.b4a.randomaccessfile.RandomAccessFile.ReadInt(RandomAccessFile.java:137)
at anywheresoftware.b4a.randomaccessfile.RandomAccessFile.ReadB4XObject(RandomAccessFile.java:319)
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 b4a.example.main.afterFirstLayout(main.java:104)
at b4a.example.main.access$000(main.java:17)
at b4a.example.main$WaitForLayout.run(main.java:82)
at android.os.Handler.handleCallback(Handler.java:815)
at android.os.Handler.dispatchMessage(Handler.java:104)
at android.os.Looper.loop(Looper.java:207)
at android.app.ActivityThread.main(ActivityThread.java:6020)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:936)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:797)
** Activity (main) Resume **