Questions and Exercises: Characters and Strings

Questions

  • What is the initial capacity of the following string builder?
StringBuilder sb = new StringBuilder("Able was I ere I saw Elba.");
  • Consider the following string:
String hannah = "Did Hannah see bees? Hannah did.";
  • What is the value displayed by the expression hannah.length() ?

    • What is the value returned by the method call hannah.charAt(12) ?

    • Write an expression that refers to the letter b in the string referred to by hannah .

  • How long is the string returned by the following expression? What is the string?

"Was it a car or a cat I saw?".substring(9, 12)
  • In the following program, called ComputeResult, what is the value of result after each numbered line executes?
public class ComputeResult {
    public static void main(String[] args) {
        String original = "software";
        StringBuilder result = new StringBuilder("hi");
        int index = original.indexOf('a');

/*1*/   result.setCharAt(0, original.charAt(0));
/*2*/   result.setCharAt(1, original.charAt(original.length()-1));
/*3*/   result.insert(1, original.charAt(4));
/*4*/   result.append(original.substring(1,4));
/*5*/   result.insert(3, (original.substring(index, index+2) + " ")); 

        System.out.println(result);
    }
}

Exercises

  • Show two ways to concatenate the following two strings together to get the string "Hi, mom." :
String hi = "Hi, ";
String mom = "mom.";
  • Write a program that computes your initials from your full name and displays them.

  • An anagram is a word or a phrase made by transposing the letters of another word or phrase; for example, "parliament" is an anagram of "partial men," and "software" is an anagram of "swear oft." Write a program that figures out whether one string is an anagram of another string. The program should ignore white space and punctuation.

Check your answers.