How to allow string to change buffer?

[eraserwars]

I want to make a sort of simple menu in this program, but I can't seem to make the string "command" change. I couldn't understand the buffer string concept, and char only applies to single letters, numbers, or symbols. Is there some way to keep entering words into "command" whether it is a char or a string? This is was easier in C++ because strings were not immutable. Could you please suggest a solution?

import java.util.Scanner;
import java.lang.StringBuffer;

public class Driver {



public static void main(String[] args) {
Scanner in = new Scanner(System.in);
Coins CoinsdHsu = new Coins();
String command = "";

System.out.println("Enter commands, enter Menu to view options");

while(true){
System.out.println("Command: ");
command = in.nextString();

if(command == "Menu"){
CoinsdHsu.menu();
}else if(command == "Enter number of cents"){
CoinsdHsu.howMany();
}else if(command == "Calculate coin distribution"){
CoinsdHsu.calculate();
}else if(command == "Stop"){
break;
}else{
System.out.println("Enter a valid command");
}
}

}
}

class Coins {

private int numCents;

public Coins(){};

public void calculate() {

int numQuarter = numCents / 25;
int quarterRemain = numCents % 25;
int numDime = quarterRemain / 10;
int dimeRemain = quarterRemain % 10;
int numNickel = dimeRemain / 5;
int numPenny = dimeRemain % 5;

System.out.println(numCents + " cents =>");
System.out.println("Quarter(s)\t" + numQuarter);
System.out.println("Dime(s)\t\t" + numDime);
System.out.println("Nickel(s)\t" + numNickel);
System.out.println("Penny(s)\t" + numPenny);
System.out.println("");
}

public void howMany(){
int cents;

Scanner in = new Scanner(System.in);

System.out.print("Number of cents: ");
cents = in.nextInt();

numCents = cents;
}

public void menu(){
System.out.println("Enter number of cents\nCalculate coin distribution\nStop\n");
}

}

[eraserwars]

Oh I know in.nextString doesn't work now, but I just need some kind of way to enter different words into strings.

[r035198x]

Don't use == to compare strings. Use the equals method instead.

[Tassos Souris]

I suggest controlling the menu options with plain integers. Use a function that displays the menu to the user, get the user input and return a appropriate code.
The codes could be:

public enum Menu{
        MENU_ENTER_CENTS,
        MENU_CALC_COIN_DISTR,
        MENU_STOP,
        MENU_INVALID
}
 

The function would be something like that:

public Menu getMenuOption(){
        // Get user's input
       return ( Menu.(OPTION) );
}
 

The menu processing code now more elegantly can be written as:

Menu option;
while ( ( option = getMenuOption() ) != Menu.MENU_STOP ){
        switch( option ){
        case MENU_ENTER_CENTS:
                // do
                break;
        case MENU_CALC_COIN_DISTR:
                // do
               break;
        // ....
        default:
               // do
               break;
        }
}
 

Hope i helped,
Tassos Souris

[JosAH]

There's a litle article on this issue in the Insights section here.

kind regards,

Jos