How to get the temporary directory path in Java

To get the temporary directory path in Java you can use the java.io.tmpdir system property. The JVM sets this property when it starts and points to the default temporary directory for the operating system.

System.getProperty("java.io.tmpdir");

The following code snippet shows a simple program that logs the temporary directory when the application starts:

public class TempDir {
  public static void main(String[] args) {
    System.out.println("Temporary directory: " + System.getProperty("java.io.tmpdir"));
  }
}

When executed, the program will output the following:

Temporary directory: /tmp

What are the default temporary directories for each operating system?

• Windows: %USERPROFILE%\AppData\Local\Temp
• Linux: /tmp
• macOS: /tmp

How to change the temporary directory path in Java?

The JVM automatically sets the temporary directory path as a system property. However, you can change it by setting the java.io.tmpdir property to the desired path when starting the JVM.

java -Djava.io.tmpdir=$TEMP_DIR -jar my-app.jar

Alternatively, you can use the JAVA_TOOL_OPTIONS environment variable, which is useful in containerized environments where you can't easily modify the JVM arguments:

export JAVA_TOOL_OPTIONS="-Djava.io.tmpdir=$TEMP_DIR"
java -jar my-app.jar

Trailing slash inconsistency

Be aware that the value returned by java.io.tmpdir may or may not include a trailing slash depending on the platform.