Question:
How does one change the current working directory of a Java program or a java.lang.Process? The equivalent of the Unix chdir system call seems to be absent.
Answer:
There is no way to change the current working directory of a Java program. If your application needs to keep track of directories, you should start off by using System.getProperty(“user.dir”) to get the current working directory. Store this in a variable that tracks the current directory, and, as you change the notion of current directory in your program, update the variable. This is usually necessary for Java programs that look for files in relative directories and need to construct absolute paths.
Sometimes Java programs need to spawn other programs using Runtime.exec, but the programs require a different working directory than the current one used by the Java program. To change the initial directory of an execed program, you have to depend on the system shell for your platform (if you have one). For Unix, just calling something like runtime.exec(“cd ” + newDirectory + “; ” + commandName) will do what you need. An alternative is just to write a simple script that sets up the environment for the command and call the script from your Java program.
