Character Addition in Java

import java.util.*;
public class arraysquare {
	public static void main(String[] args) {
	Scanner sc=new Scanner(System.in);
	System.out.println("Enter the customer instrution");
	String str=sc.nextLine();
	String w=str.substring(0,4);
	int weight=0,order_no=0;
	String order=str.substring(str.length()-3);
	String flavor=str.substring(4,str.length()-3);
	if(!(str.matches("[a-zA-z0-9]+"))) {
		System.out.println("Invalid Instruction");
		return;
	}
	else if(w.contains("[0-9]+" )) {
		weight=Integer.parseInt(w);
		System.out.println("Invalid weight");
		return;
	}
	 else if(!order.contains("[0-9]+")) {
		System.out.println("Invalid Oreder number");
		return;
	}
	else {
		if(weight<999) {
			System.out.println("Invalid Weight");
			return;
		}
	double kg=(Double.parseDouble(w))/1000;
	System.out.println("Cake weight is "+kg+"kg");
	System.out.println("Cake Flavor is "+flavor);
	System.out.println("Cake No is "+order);
	double price=450*kg;
	System.out.println("Price is "+String.format("%.2f",price));
	}
	}
}