Java System properties Examples

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1. How to load a properties file into System properties
1. How to Retrieve all System properties

1. How to load a properties file into System properties
This program loads all properties from a properties file directly into System properties

package io;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Properties;

public class SystemPropertiesExample {

 public static void main(String[] args) {
  FileInputStream fis = null;
  try {
   
   Properties props = new Properties();
   fis = new FileInputStream(new File("c:/temp/config.properties"));
   props.load(fis);
   System.setProperties(props);
   
  } catch (Exception e) {
   e.printStackTrace();
  } finally {
   try {
    fis.close();
    fis = null;
   } catch (IOException e) {
    e.printStackTrace();
   }
  }

 }
}

2. How to Retrieve all System properties

package io;

import java.util.Enumeration;
import java.util.Properties;

public class SystemPropertiesExample {

 public static void main(String[] args) {

  Properties props = System.getProperties();

  // Enumerate all system properties
  Enumeration enumu = props.keys();
  while (enumu.hasMoreElements()) { 
   String propName = (String) enumu.nextElement();
   String propValue = (String) props.get(propName);
   System.out.println(propName +" :: "+propValue);
  }
 }
}