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Start your free trialParamvir Singh
1,517 PointsHow do I check if the user has entered a String or not?
In one of the Tasks I was supposed to check if the user has entered a String or not, but I couldn't figure it out. I even looked at the Java API but still coundn't find anything.
public class Order {
private String itemName;
private int priceInCents;
private String discountCode;
public Order(String itemName, int priceInCents) {
this.itemName = itemName;
this.priceInCents = priceInCents;
}
private String normalizeDiscountCode (String d ) {
if ( true ) {
throw new IllegalArgumentException("Invalid discount code.");
}
this.discountCode = d.toUpperCase();
return this.discountCode;
}
public String getItemName() {
return itemName;
}
public int getPriceInCents() {
return priceInCents;
}
public String getDiscountCode() {
return discountCode;
}
public void applyDiscountCode(String discountCode) {
this.discountCode = normalizeDiscountCode( discountCode );
}
}
public class Example {
public static void main(String[] args) {
// This is here just for example use cases.
Order order = new Order(
"Yoda PEZ Dispenser",
600);
// These are valid. They are letters and the $ character only
order.applyDiscountCode("abc");
order.getDiscountCode(); // ABC
order.applyDiscountCode("$ale");
order.getDiscountCode(); // $ALE
try {
// This will throw an exception because it contains numbers
order.applyDiscountCode("ABC123");
} catch (IllegalArgumentException iae) {
System.out.println(iae.getMessage()); // Prints "Invalid discount code"
}
try {
// This will throw as well, because it contains a symbol.
order.applyDiscountCode("w@w");
}catch (IllegalArgumentException iae) {
System.out.println(iae.getMessage()); // Prints "Invalid discount code"
}
}
}
1 Answer
Kevin Grifo
9,824 PointsHi Paramvir,
You could use the instanceof operator to check if a specific object is a String. The java instanceof operator is used to test whether the object is an instance of the specified type (class or subclass or interface).
An example would be
String foo = "this Is a String"; //Checking if foo is of type string if( foo instanceof String ) { // do something String related to foo System.out.println("foo is a string!"); }
I hope this helps.