Question

How do recursively check and rename the file if it already exist by appending some incrementing number?

I wrote the below function but it gives me an exception

org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'E:\Projects\repo1\in_conv1.xml' with class 'java.lang.String' to class 'java.io.File'

Code

//newFilePath = E:\Projects\repo1\old\testcustprops.xml
String newFilePath = checkForExistenceAndRename(newFilePath,false)

private String checkForExistenceAndRename(String newFilePath, boolean flag){
    File f = new File(newFilePath)
    if(!flag){
        if(f.exists()){
            //renaming file
            newFilePath=newFilePath[0..-5]+"_conv${rename_count++}.xml"
            f = checkForExistenceAndRename(newFilePath,false)
        }
        else 
            f = checkForExistenceAndRename(newFilePath,true)
    }
    else
        return newFilePath      
}

Answer 1

You are trying to do:

f = checkForExistenceAndRename(newFilePath,false)

Where f is a File. But your function returns a String

Not sure if it works or not (I haven’t tested your function), but you could try:

private String checkForExistenceAndRename(String newFilePath, boolean flag){
    File f = new File(newFilePath)
    if(!flag){
        if(f.exists()){
            //renaming file
            newFilePath = newFilePath[0..-5]+"_conv${rename_count++}.xml"
            newFilePath = checkForExistenceAndRename(newFilePath,false)
        }
        else 
            newFilePath = checkForExistenceAndRename(newFilePath,true)
    }
    return newFilePath      
}

Also, there’s no need to use recursion…

Why not just do:

private String getUniqueName( String filename ) {
  new File( filename ).with { f ->
    int count = 1
    while( f.exists() ) {
      f = new File( "${filename[ 0..-5 ]}_conv${count++}.xml" )
    }
    f.absolutePath
  }
}