Here I am sitting, thinking of something optimistic to write about. It’s very difficult, so here’s what I came up with…

String inputDir = "/home/user/";
String inputFile = "in.txt";
if (!inputDir.endsWith("/")) inputDir += "/";
File iFile = new File(inputDir + inputFile);
String outputDir = "/home/user/backup/";
if (!outputDir.endsWith("/")) outputDir += "/";
iFile.renameTo(outputDir + inputFile);