Basket Case - Java

Get to grips with Java Server Pages with this introductorytutorial and find out how to use one of the more powerful server-sidelanguages around. This first part explains the history and basics of JSPdocuments, and also illustrates variables, includes and the String object.

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By: Vikram Vaswani and Harish Kamath, (c) Melonfire

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February 07, 2001

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The String object comes with a bunch of useful methods, which can come in handy when performing string manipulation.

The first of these is the length() method, used to obtain the (you guessed it!) length of a specific string. Let's modify the example you just saw to demonstrate how this works:

<html>
<head>
</head>
<body>
<%!
// define the variables
String apples = "Purple pigs ";
String oranges = "riding orange pumpkins";
String fruitBasket;
%>
<%
// print the first two strings
out.println("<b>The first string is</b>: " + apples + "<br>");
out.println("<b>The second string is</b>: " + oranges + "<br>");
// concatentate the strings
fruitBasket = apples + oranges;
// display
out.println("<b>And the combination is</b>: "  + fruitBasket + "(" +
fruitBasket.length() + " characters)<br>Who says you can't add apples and
oranges?!");
%>
</body>
</html>

And the output is:


The first string is: Purple pigs
The second string is: riding orange pumpkins
And the combination is: Purple pigs riding orange pumpkins(34 characters)
Who says you can't add apples and oranges?!

You can extract a specific character from the string with the charAt() method, which accepts an offset as parameter. For example, the following code snippet would return the character "o":

<%
String name = "Bozo The Clown";
out.println(name.charAt(3));
%>

Note that the offset 0 indicates the first character, since Java, like many of its counterparts, uses zero-based indexing.

You can also extract a segment of a string with the substring() method, which allows you to specify the start and end points of the string segment to be extracted. Take a look at this sentence and see if you can spot the hidden message within it:

<%!
String me = "I am a highly-skilled and hardworking developer!";
%>

No? How about now?

<%!
String me = "I am a highly-skilled and hardworking developer!";
String message;
%>
<%
message = me.substring(0,2) + me.substring(15,22) + me.substring(26,27) +
me.substring(45,48);
out.println(message);
%>

And here's the output: