B4J Question How to create a File object ? (FileSystemView)

jmon · Mar 14, 2014

Hello,

I am trying to convert some functions on this page : http://docs.oracle.com/javase/7/docs/api/javax/swing/filechooser/FileSystemView.html

B4X:

Public Sub isDrive(Path As String) As Boolean
    Dim FileJO As JavaObject
    FileJO.InitializeStatic("java.io.File")
   
    Dim FileSystemView As JavaObject
    FileSystemView.InitializeStatic("javax.swing.filechooser.FileSystemView")
    FileJO = FileSystemView.RunMethod("createFileObject", Array As String(Path))
   
    Return FileSystemView.RunMethod("isDrive", Array As Object(FileJO))
End Sub

Sub AppStart (Args() As String)
    Log(isDrive("C:\"))

End Sub

But with this code, I get this error :

main._isdrive (java line: 70)
java.lang.IllegalArgumentException: object is not an instance of declaring class
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:80)
at b4j.example.main._isdrive(main.java:70)
at b4j.example.main._appstart(main.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:93)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:84)
at b4j.example.main.main(main.java:26)

I don't get it. I tried so many variations of this code, but no luck so far.

Thanks for your help.
jmon

Erel · Mar 14, 2014

You do not need to initialize FileJO in the code above.
Add this line:

B4X:

FileSystemView = FileSystemView.RunMethod("getFileSystemView", null)

jmon · Mar 14, 2014

Thanks,

With this new code I am getting a different error :

B4X:

Public Sub isDrive(Path As String) As Boolean
    Dim FileSystemView As JavaObject
    FileSystemView.InitializeStatic("javax.swing.filechooser.FileSystemView")
    FileSystemView = FileSystemView.RunMethod("getFileSystemView", Null)
   
    Dim FileJO As JavaObject
    FileJO = FileSystemView.RunMethod("createFileObject", Array As Object(Path))
   
    Return FileSystemView.RunMethod("isDrive", Array As Object(FileJO))
End Sub

main._isdrive (java line: 70)
java.lang.IllegalAccessException: Class anywheresoftware.b4j.object.JavaObject can not access a member of class javax.swing.filechooser.WindowsFileSystemView with modifiers "public"
at sun.reflect.Reflection.ensureMemberAccess(Reflection.java:109)
at java.lang.reflect.AccessibleObject.slowCheckMemberAccess(AccessibleObject.java:261)
at java.lang.reflect.AccessibleObject.checkAccess(AccessibleObject.java:253)
at java.lang.reflect.Method.invoke(Method.java:599)
at anywheresoftware.b4j.object.JavaObject.RunMethod(JavaObject.java:80)
at b4j.example.main._isdrive(main.java:70)
at b4j.example.main._appstart(main.java:53)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at anywheresoftware.b4a.BA.raiseEvent2(BA.java:93)
at anywheresoftware.b4a.BA.raiseEvent(BA.java:84)
at b4j.example.main.main(main.java:26)

The error happens on the "createFileObject" method. Any idea?

Thanks

Erel · Mar 16, 2014

It will not work with JavaObject. It happens because the class returned is not public (only the interface). It should be possible to do it with jReflector library.

B4J Question How to create a File object ? (FileSystemView)

jmon

Well-Known Member

Erel

B4X founder

jmon

Well-Known Member

Erel

B4X founder

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B4J Question How to create a File object ? (FileSystemView)

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