Get/set system property

static String clearProperty(String key): Removes the system property.
static String getenv(String name): Gets the value of the specified environment variable.
static Properties getProperties(): Determines the current system properties.
static String getProperty(String key): Gets the system property.
static String getProperty(String key, String def): Gets the system property.
static void setProperties(Properties props): Sets the system properties to the Properties argument.
static String setProperty(String key, String value): Sets the system property.

The following properties are available:

file.separator
java.class.path
java.class.version
java.compiler
java.ext.dirs
java.home
java.io.tmpdir
java.library.path
java.specification.name
java.specification.vendor
java.specification.version
java.vendor
java.vendor.url
java.version
java.vm.name
java.vm.specification.name
java.vm.specification.vendor
java.vm.specification.version
java.vm.vendor
java.vm.version
line.separator
os.arch
os.name
os.version
path.separator
user.dir
user.home
user.name


public class Main {

  public static void main(String args[]) {
    System.setProperty("myKey", "myValue");
    
    System.out.println(System.getProperty("myKey"));

  }
}

The output:


myValue

Determine operating system using System class

 

public class Main {
  public static void main(String[] args) {
    String strOSName = System.getProperty("os.name");
    if (strOSName != null) {
      if (strOSName.toLowerCase().indexOf("windows") != -1)
        System.out.println("Windows");
      else
        System.out.print("not windows");
    }
  }
}


Windows

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