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Java Java Objects Delivering the MVP Validating and Normalizing User Input

Maan Azzam
Maan Azzam
2,239 Points
Posted by Maan Azzam
Maan Azzam
2,239 Points

Challenge problems.

Can someone tell me if what i wrote can work (with some modifications) or should i just use

for (char letter: discountCode.charArray())

first to change the String into char.

Challenge question #2 : In the normalizeDiscountCode verify that only letters or the $ character are used. If any other character is used, throw a IllegalArgumentException with the message Invalid discount code.

My "wrong" Answer : 

public void applyDiscountCode(String discountCode) {
    this.discountCode = normalizeDiscountCode(discountCode);

  }

  private String normalizeDiscountCode(String discountCode) {
    if(!Character.isLetter(discountCode.charAt(0)) || !discountCode.contains("$")  ) {
      throw new IllegalArgumentException("Invalid discount code");
    }    
    return this.discountCode = discountCode.toUpperCase();
  }

Please keep in mind that i dont get Compiler errors. just that i dont pass the challenge.

1 Answer

Jialong Zhang
Jialong Zhang
9,821 Points
Jialong Zhang
Jialong Zhang
9,821 Points

I think there is a logic problem this line. for the second part, if a string does not contain $, it will throw a IllegalArgumentException. Giving string "Hello", it will also throw IllegalArgumentException because this string does not contain $.

if(!Character.isLetter(discountCode.charAt(0)) ||  !discountCode.contains("$")  ) { // logic error , however, change || to && will not fix the problem.

// I don't know if this challenge only needs to check first character or all character.

//my solution is something like 

     public String normalizeDiscountCode(String discountCode) {
        for(int i =0; i< discountCode.length(); i++){
             if(!Character.isLetter(discountCode.charAt(i)) && !discountCode.substring(i,i+1).equals("$") ) {
                  throw new IllegalArgumentException("Invalid discount code");
                }    
             this.discountCode = discountCode.toUpperCase();
              }

            return discountCode;
        }