8: Adding Forms in Java

Maker Code-39 in Java 8: Adding Forms

Of course, a typical form uses several of the same INPUT types over and over again You ll need to give each element a particular name in order to distinguish it from similar elements Otherwise it would be impossible to tell the difference between (for example) the three text boxes asking for a visitor s first name, middle initial, and last name You do this via the name attribute, as you might expect The example just mentioned would be coded like this: <FORM> <INPUT type= text name= firstname > <INPUT type= text name= middleinitial > <INPUT type= text name= lastname > </FORM>

Text boxes are simple, one-line rectangles that typically contain information such as names and addresses, and you ve got a bunch of options you can specify when it comes to using them The most obvious of these is setting the length of the text box This capability enables you to create a more pleasing layout and (incidentally) save space To expand on the example in the preceding section, you might set the length of the user name text boxes like this: <FORM> First Name: <INPUT type= text name= firstname size= 15 > Middle Initial: <INPUT type= text name= middleinitial size= 1 > Last Name: <INPUT type= text name= lastname size= 20 > </FORM> Figure 8-3 shows the results (note that, despite the size limit on the middle initial, both Firefox and Internet Explorer expand it to three characters) The size attribute specifies the number of typed characters, not the number of pixels, and the width of characters depends on the font being used Of course, when it comes to setting the length, you have to just take your best shot at what will work best Some last names are five letters long whereas others may be more than 20 Fortunately, the size of the text box doesn t actually limit the size of the data entered into it If someone types a 100-character entry into a size 20 text box, all 100 characters will still be entered, and the text will simply scroll as it s typed

But what if the program you re using to process the data has a limit on the size of the data it will accept This is a pretty common situation, and you ll be happy to know that there s a simple way to handle this problem: You use the maxlength attribute The following code shows how to adapt our example to accept no more than a particular number of characters: <FORM> <INPUT type= text name= firstname size= 15 maxlength= 50 > <INPUT type= text name= middleinitial size= 1 maxlength= 1 > <INPUT type= text name= lastname size= 20 maxlength= 50 > </FORM> In this case, the first and last names are limited to 50 characters in length; the middle initial, of course, is set to a single character If you re using a form that requires a user to enter a password, it s customary to use, in the place of a regular text box, a specialized password text box that you guessed it you enter by typing this line: <INPUT type= password >

With password text boxes, when a user enters his or her password, a series of asterisks is shown instead of the typed letters, thus protecting the user s security if someone else is peeking at the screen That s the only difference; You use the same options as with regular text boxes The following code sets up the example shown in Figure 8-4: <FORM> User Name: <INPUT type= text name= username size= 25 maxlength= 50 > <BR> <BR> Password: <INPUT type= password name= middleinitial size= 25 maxlength= 50 > </FORM>