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CommentBox Help

Help is available for each task, or you can go straight to the CommentBox source code to see a solution.

Task 1

Create an Applet to hold one instance of CommentBox so that you can test the component.

You need to create a class separate from your CommentBox class. You can call it CommentBoxTest. In this class, create an instance of CommentBox and add it to the container. 

import java.awt.*;

public class CommentBoxTest extends java.applet.Applet {
    public void init() {
        CommentBox test = new CommentBox();
        add(test);
    }
}

Task 2

 Create a class called CommentBox as a subclass of FormElement. 

public class CommentBox extends FormElement {
    ...
}

Task 3

 In the class CommentBox, create a centered Label and a TextArea below it. Make the TextArea display three lines of 55 characters.

You have to create a constructor to initialize the components needed by the compound component, and add them to the current Container. In this case, the Container is a Panel since FormElement subclasses Panel: 

class CommentBox extends FormElement {
    protected TextArea text;
    protected String   label = "Comments";
    public CommentBox() {
        setLayout(new BorderLayout());
        text = new TextArea(3, 55);
        add("North",  new Label(label, Label.CENTER));
        add("Center", text);
    }
    ...
}

text and label are instance variables so that other methods in this class will have access to them.

Task 4

Implement the method isEmpty of FormElement to return true if the TextArea is empty. 

public boolean isEmpty() {
    return text.getText().equals("");
}

Task 5

 Implement the method getContents of FormElement. It should return the Label and the contents of the CommentBox. 

public String getContents() {
    return label + "    " + text.getText();
}