Here you go,
import java.util.Scanner; 
import java.util.Random; 
 
public class OrderCalculator{ 
 public static void main(String[] args){ 
 float x, y, z, semi, area; 
 Scanner in = new Scanner(System.in); 
 System.out.print("Enter the 3 sides: "); 
 x = in.nextFloat(); 
 y = in.nextFloat(); 
 z = in.nextFloat(); 
 semi = (float) ((x + y + z) / 2.0); 
 area = (float) Math.sqrt(semi * (semi - x) * (semi - y) * (semi - z)); 
 System.out.printf("The area is: %.3f\\", area); 
 } 
}