Summary of Strings

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

Summary of Strings

The following table summarizes the methods found in the String and StringBuffer classes.

Summary of the String Class

Method or Constructor Purpose

String() String (byte[]) String (byte[], int, int) String (byte[], int, int, String) String (byte[], String) String (char[]) String (char[], int, int) String (String) String (StringBuffer) Creates a new string object. For all constructors that take arguments, the first argument provides the value for the string.

Other Interesting Features

String and StringBuffer provide several other useful ways to manipul ate string data, including concatenation, comparison, substitution, and conversion to upper and lower case. java.lang.String

and java.lang.StringBuffer

summarize and list all of the methods and variables supported by these two classes.

Here's a fun program, Palindrome, that determines whether a string is a palindrome. This program uses many methods from the String and the StringBuffer classes:

public class Palindrome {
    public static boolean isPalindrome(String stringToTest) {
        String workingCopy = removeJunk(stringToTest);
        String reversedCopy = reverse(workingCopy);

        return reversedCopy.equalsIgnoreCase(workingCopy);
    }

    protected static String removeJunk(String string) {
        int i, len = string.length();
        StringBuffer dest = new StringBuffer(len);
        char c;

        for (i = (len - 1); i >= 0; i--) {
            c = string.charAt(i);
            if (Character.isLetterOrDigit(c)) {
                dest.append(c);
            }
        }

        return dest.toString();
    }

    protected static String reverse(String string) {
        StringBuffer sb = new StringBuffer(string);

        return sb.reverse().toString();
    }

    public static void main(String[] args) {
        String string = "Madam, I'm Adam.";

        System.out.println();
        System.out.println("Testing whether the following "
                           + "string is a palindrome:");
        System.out.println("    " + string);
        System.out.println();

        if (isPalindrome(string)) {
            System.out.println("It IS a palindrome!");
        } else {
            System.out.println("It is NOT a palindrome!");
        }
        System.out.println();
    }
}

The output from this program is:

Testing whether the following string is a palindrome:
    Madam, I'm Adam.

It IS a palindrome!

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