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Trail: Learning the Java Language
Lesson: Object Basics and Simple Data Objects

Questions and Exercises: Strings

Questions

  1. What is the initial capacity of the following string buffer?
    StringBuffer sb = new StringBuffer("Able was I ere I saw Elba.");
    

  2. Consider the following string:
    String hannah = "Did Hannah see bees? Hannah did.";
    
    1. What is the value displayed by the expression hannah.length()?
    2. What is the value returned by the method call hannah.charAt(12)?
    3. Write an expression that refers to the letter b in the string referred to by hannah.

  3. 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)
    

  4. In the following program, called ComputeResult(in a .java source file), what is the value of result after each numbered line executes?
    public class ComputeResult {
        public static void main(String[] args) {
            String original = "software";
            StringBuffer result = new StringBuffer("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

  1. Show two ways to concatenate the following two strings together to get the string "Hi, mom.":
    String hi = "Hi, ";
    String mom = "mom.";
    
  2. Write a program that computes your initials from your full name and displays them.
  3. 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.(in the Learning the Java Language trail)

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