public void renameFile(String file, String toFile) {

        File toBeRenamed = new File(file);
        //检查要重命名的文件是否存在，是否是文件
        if (!toBeRenamed.exists() || toBeRenamed.isDirectory()) {

            System.out.println("File does not exist: " + file);
            return;
        }

        File newFile = new File(toFile);

        //修改文件名
        if (toBeRenamed.renameTo(newFile)) {
            System.out.println("File has been renamed.");
        } else {
            System.out.println("Error renmaing file");
        }

    }

renameFile("C:\\temp\\file1.txt", "C:\\temp\\file2.txt");