Question

I have a problem about the last part of the code. I want to assign numbers to specific words but i always get 0 value, even though I get those strings from the first System.out.println correctly, i cannot get the numerical equivalents of those strings at the second System.out.println.Any ideas how to solve this problem?

public static double number;

protected void myMethod(HttpServletRequest request, HttpServletResponse response) {

    String speech= request.getParameter("speech");
    System.out.println("The recognized speech is : "+ speech);

    // There is no problem till here.
    if(speech == "Hi")
        number = 1 ;
    if(speech== "Thanks")
        number = 2 ;
    if(speech== "Bye")
        number = 0 ;

    System.out.println("The number for the speech is : " + number);
}

However here i dont get the correct numbers but only 0 for each word!

Answer 1

You can’t use the == operator to check if two Strings have the same value in Java, you need to use the .equals() or equalsIgnoreCase() methods instead:

if("Hi".equalsIgnoreCase(speech)) {
    number = 1;
}
else if("Thanks".equalsIgnoreCase(speech)) {
    number = 2;
}
else if("Bye".equalsIgnoreCase(speech)) {
    number = 0;
}
else {
    number = -1;
}

The reason for this is that the == operator compares references; that is it will return true if and only if the instance stored in variable speech is the same instance as the literal String you’ve created between double quotes ("Hi", "Thanks", or "Bye").

Note also that I use the equalsIgnoreCase() call on the literal String I’m declaring, rather than the variable that is assigned from the parameter. This way, if a speech == null, the method call is still valid ("Hi" will always be a String), and so you won’t get a NullPointerException, and the flow will continue until the else branch.