Special Effects and Game Development in Java(TM) -Other examples with showStatus()


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Special Effects and Game Development in Java(TM) - Other examples with showStatus()

by Anibal Wainstein

3.1 Other examples with showStatus()

Status window effects are often used among web designers today. Thanks to our new knowledge in threads, we can begin making some status window animations.

3.1.1 Your first scroller (statusscroller)

I remember that the first applet I programmed was an applet called URLScroll. It was one of the most common effects at that time, and they usually were a text message that moved from right to left or upwards. We reviewed in section 1.4.1 how to get a substring from a larger string. Start by opening the old threadtest.java file and save a copy under another name ("statusscroller" for instance). Now we add an init() method where the message will be initialized:



public String message;
public void init()
{
    message="                              ";
    message+="                              ";
    message+="                              ";
    message+="                              ";
    message+="Anibal Wainstein's Basic Course ";
    message+="in Special Effects and Game development in Java(TM)";}

First we declare a global variable called "message". This will contain the actual message that we will write. We start by initializing the variable with a blankspace line and then by adding more subsequent blankspace lines. The message is added at the end of these lines. If you are confused by the way I am creating the message then you should know that:

message="message 1 ";
message+="message 2";

is the same thing as

message="message 1 " + "message 2";

The idea with our scroller is that we crop the string and show shorter and shorter bits on the status window until there is nothing left to show. Rewrite the run() method in the old applet:

public void run()
{
    while (true)
    {
        int L=message.length();
        for (int i=0; i<L; i++)
        {
            showStatus(message.substring(i,L));
            try {Thread.sleep(100);}
            catch(InterruptedException e) {}
        }
    }
}

Here, we start by first finding out the length of our string, with the help of the String class' length() method, the result is stored in the variable "L". The for-loop will count up from position 0 in the string, to the end of the message. Substring() can then take the part of the string that begins on this position and ends at the end of the string, that is the "L" position. We add a pause of one tenth of a second (100 milliseconds) after displaying the string. When the string has been cropped to the end, then the whole process start again, thanks to us having contained the code within the infinite while loop.
Take a look at the finished statusscroller by clicking here .

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