The System class contains several useful class fields and methods. It cannot be instantiated.
Among the facilities provided by the System class are
- standard input(in), standard output(out), and standard error output(err) streams;
- access to externally defined properties and environment variables;
- a means of loading files and libraries;
- a utility method for quickly copying a portion of an array.
Utility Methods
Java Code
package com.java.core;
import java.io.IOException;
public class SystemExample {
public static void main(String[] args) throws IOException {
System.out.println("currentTimeMillis:" + System.currentTimeMillis());
System.out.println("nanoTime:" + System.nanoTime());
System.out.println("Env Map:" + System.getenv());
System.out.println("Properties:" + System.getProperties());
System.err.println("Error Message");
System.gc();
System.exit(0);
}
}
Output
currentTimeMillis:1587094201157
nanoTime:640933913473059
Env Map:{....JAVA_MAIN_CLASS_24013=com.java.core.SystemExample...}
Properties:{...java.specification.version=1.8,...}
Error Message
