java.nio.file.FileAlreadyExistsException : i am attempting to copy one file to another location using java nio api. When i run below code i get java.nio.file.FileAlreadyExistsException.

    public static void copyFileUsingNio(File sourceFile, String destnationFilePath) {
    		try {	
    			if (sourceFile != null && destnationFilePath != null) {
    				
    				java.nio.file.Path sourcePath = sourceFile.toPath();
    				java.nio.file.Path destinationPath = java.nio.file.Paths.get(destnationFilePath);
    				
    				if (!java.nio.file.Files.exists(destinationPath)) {
    					java.nio.file.Path parent = destinationPath.getParent();
    					if (parent != null) {
    						java.nio.file.Files.createDirectories(destinationPath.getParent());
    						java.nio.file.Files.createFile(destinationPath);	
    					}
    					destinationPath = java.nio.file.Files.copy(sourcePath, destinationPath, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
    				} else {
    					destinationPath = java.nio.file.Files.copy(sourcePath, destinationPath, java.nio.file.StandardCopyOption.REPLACE_EXISTING);
    				}
    			}
    		} catch(Exception e) {
    			e.printStackTrace();
    		}
    	}

Here destnationFilePath  is **C:/Users/guest/Desktop/Files/desttest.txt**. Also if file already exists then i need to replace it else copy the file.
Please advice me.