Introduction to AWT

AWT Definition

AWT: A GUI class library, the Abstract Window Toolkit
GUI applications created with AWT share the same interface style as the platform on which they run

Inheritance System of AWT

Componet:

Represents an object that can be displayed pictorially and interact with the user, such as Button for a button, TextField for a text box, etc.

MenuComponent:

Menu components that represent the graphical interface, including subclasses such as MenuBar (menu bar), MenuItem (menu item)

Container:

Is a special kind of Componet that represents a container that can hold ordinary COMponents

Container's Inheritance System

AWT usage

Use of Window,Panel,ScrollPane

• Window is a stand-alone top-level window that manages its internal component layout by default using BorderLayout
• Panel can accommodate other components but cannot exist independently. It must be used inside other containers, and FlowLayout is used by default to manage its internal component layout
• ScrollPane is a container with scrollbars and cannot exist independently. BorderLayout is used by default to manage its internal component layout

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Window:

public class WindowDemo {
    public static void main(String[] args) {
        Frame frame = new Frame("window");

        frame.setLocation(100, 100); //Set Location
        frame.setSize(500, 300); //Set window size
        frame.setVisible(true); // Set Visibility
    }
}

Panel:

public class PanelDemo {
    public static void main(String[] args) {
        //Panel object must be dependent on Window
        
        //Create a window object
        Frame frame = new Frame("panel");

        //Create Panel Object
        Panel panel = new Panel();
        panel.add(new TextField("textField"));  // Add Text Box
        panel.add(new Button("button"));  // add button

        //panel added to window
        frame.add(panel);

        //Set window position and size
        frame.setBounds(100, 100, 500, 300);

        //Set window s visibility
        frame.setVisible(true);
    }
}

ScrollPane:

public class ScrollPanelDemo {
    public static void main(String[] args) {
        //Create a window object
        Frame frame = new Frame("ScrollPane");

        //Create Panel Object
        ScrollPane scrollPane = new ScrollPane(ScrollPane.SCROLLBARS_ALWAYS);  //Setting the scrollbar to always display
        scrollPane.add(new TextField("textField"));
        scrollPane.add(new Button("button"));

        //panel added to window
        frame.add(scrollPane);

        //Set window position and size
        frame.setBounds(100, 100, 500, 300);

        //Set window s visibility
        frame.setVisible(true);
    }
}

Layout Manager

• LayoutMananger Layout Manager can automatically resize components based on the running platform

FlowLayout

• Arrange all components from left to right, and when boundaries are encountered, fold back to the next line to start over

public class FlowLayoutDemo {
    public static void main(String[] args) {
        Frame frame = new Frame("FlowLayout");

        // Set up Layout Manager with left alignment, horizontal and vertical spacing of 20
        frame.setLayout(new FlowLayout(FlowLayout.LEFT, 20, 20));

        for (int i = 0; i < 100; i++) {
            frame.add(new Button("button" + i));
        }

        //Set optimal size
        frame.pack();
        frame.setVisible(true);
    }
}

BorderLayout

• Containers are divided into five zones: EAST,SOUTH,WEST,NORTH,CENTER. Common components can be placed in any of these five zones
• When changing the container size using BorderLayout, the NORTH,SOUTH, and CENTER regions are adjusted horizontally, while the EAST,WEST, and CENTER regions are adjusted vertically
• When adding components, you need to specify which zone to add, and if you don't specify which zone to add, add them by default to the middle zone
• If more than one component is added to the same zone, the component that is put later overwrites the component that was put first

public class BorderLayoutDemo {
    public static void main(String[] args) {
        Frame frame = new Frame("BorderLayout");

        // Horizontal spacing 30, Vertical spacing 10
        frame.setLayout(new BorderLayout(30, 10));

        frame.add(new Button("North"), BorderLayout.NORTH);
        frame.add(new Button("South"), BorderLayout.SOUTH);
        frame.add(new Button("East"), BorderLayout.EAST);
        frame.add(new Button("West"), BorderLayout.WEST);
        frame.add(new Button("Center"), BorderLayout.CENTER);

        frame.pack();
        frame.setVisible(true);
    }
}

GridLayout

• Split containers into grids with vertical and horizontal lines, each of which occupies the same size of area
• When adding components, add them to each grid by default from left to right, top to bottom

public class GridLayoutDemo {

    public static void main(String[] args) {
        Frame frame = new Frame("GridLayout");

        // Add Input Text Box
        Panel p_text = new Panel();
        p_text.add(new TextField(30));
        frame.add(p_text, BorderLayout.NORTH);

        //Add Array
        Panel p_num = new Panel();
        // 3 rows 5 columns
        p_num.setLayout(new GridLayout(3, 5, 4, 4));
        for (int i = 0; i < 10; i++) {
            p_num.add(new Button(String.valueOf(i)));
        }
        p_num.add(new Button("+"));
        p_num.add(new Button("-"));
        p_num.add(new Button("*"));
        p_num.add(new Button("/"));
        p_num.add(new Button("."));
        frame.add(p_num);

        frame.pack();
        frame.setVisible(true);
    }
}

GridBagLayout

• Similar to GridLayout, but the layout can occupy multiple grids

CardLayout

• Consider all components added to the container as a stack of cards, with only the top component visible at a time.

public class CardLayoutDemo {
    public static void main(String[] args) {
        Frame frame = new Frame("CardLayout");

        CardLayout cardLayout = new CardLayout();

        //Middle area panel
        Panel p1 = new Panel();
        p1.setLayout(cardLayout);
        String[] names = {"First","Second","Third","Fourth","Fifth"};
        for (int i = 0; i < names.length; i++) {
            p1.add(names[i], new Button(names[i]));
        }
        frame.add(p1);

        //Five button areas
        Panel p2 = new Panel();
        Button b1 = new Button("Previous");
        Button b2 = new Button("Next");
        Button b3 = new Button("First");
        Button b4 = new Button("Last");
        Button b5 = new Button("Third");

        //Create an event listener to listen for button clicks
        ActionListener listener = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent actionEvent) {
                // Get the text on the button
                String actionCommend = actionEvent.getActionCommand();
                switch (actionCommend) {
                    case "Previous":
                        cardLayout.previous(p1);
                        break;
                    case "Next":
                        cardLayout.next(p1);
                        break;
                    case "First":
                        cardLayout.first(p1);
                        break;
                    case "Last":
                        cardLayout.last(p1);
                        break;
                    case "Third":
                        cardLayout.show(p1, "Third");
                        break;
                }
            }
        };

        //Bind event listeners and buttons together
        b1.addActionListener(listener);
        b2.addActionListener(listener);
        b3.addActionListener(listener);
        b4.addActionListener(listener);
        b5.addActionListener(listener);

        p2.add(b1);
        p2.add(b2);
        p2.add(b3);
        p2.add(b4);
        p2.add(b5);
        frame.add(p2, BorderLayout.SOUTH);

        frame.pack();
        frame.setVisible(true);
    }
}

BoxLayout

• GUI components can be accessed vertically and horizontally

public class BoxLayoutDemo {
    public static void main(String[] args) {
        Frame frame = new Frame("BoxLayout");

        //Create a BoxLayout object that holds components vertically
        BoxLayout boxLayout = new BoxLayout(frame, BoxLayout.Y_AXIS);

        frame.setLayout(boxLayout);
        frame.add(new Button("button1"));
        frame.add(new Button("button2"));

        frame.pack();
        frame.setVisible(true);
    }
}

Box Container

• The container's default layout manager is BoxLayout. In most cases, use the Box container to hold multiple GUI components, then add the Box container as a component to other containers to form the overall window layout.

public class BoxDemo {
    public static void main(String[] args) {
        Frame frame = new Frame("Box");

        //Create Box Containers for Horizontally Arranged Components
        Box hBox = Box.createHorizontalBox();
        hBox.add(new Button("h_button1"));
        hBox.add(Box.createHorizontalGlue()); // Stretch in both directions
        hBox.add(new Button("h_button2"));
        hBox.add(Box.createHorizontalStrut(30)); //Fixed split length
        hBox.add(new Button("h_button3"));

        //Create Box Containers for Vertically Arranged Components
        Box vBox = Box.createVerticalBox();
        vBox.add(new Button("v_button1"));
        vBox.add(Box.createVerticalGlue());
        vBox.add(new Button("v_button2"));
        vBox.add(Box.createVerticalStrut(30));
        vBox.add(new Button("v_button3"));

        //Add to frame
        frame.add(hBox, BorderLayout.NORTH);
        frame.add(vBox);

        frame.pack();
        frame.setVisible(true);
    }
}

Basic components in AWT

Component Name	function
Button	Button
Canvas	Canvas for Drawing
Checkbox	Checkbox components (also used when cell box components)
CheckboxGroup	Used to group multiple Checkbox components into a group, where only one Checkbox component is selected, that is, all become radio box components
Choice	Select
Frame	Window, through which windows are created in GUI programs
Label	Label class for placing prompt text
List	List box component that adds multiple entries
Panel	Basic container classes cannot exist separately and must be placed in other containers
Scrollbar	Slider bar component. If you need the user to enter a value that is within a range, you can use the slider component, such as the slider used to set the three values of RGB in the color palette. When you create a slider bar, you must specify its direction, initial value, size of the slider, minimum value, and maximum value.
ScrollPane	Container assembly with horizontal and vertical sliders
TextArea	Multiline Text Fields
TextField	JTextField

public class BasicComponentDemo {
    Frame frame = new Frame("Basic Components");

    //Multiline Text Area
    TextArea ta = new TextArea(5, 20);

    //Select
    Choice colorChooser = new Choice();

    //Selection box
    CheckboxGroup cbg = new CheckboxGroup();
    Checkbox male = new Checkbox("male", cbg, true);
    Checkbox female = new Checkbox("female", cbg, false);

    //Selection box
    Checkbox isMarried = new Checkbox("Were you married?");

    //Single Line Text Area
    TextField tf = new TextField(50);
    Button ok = new Button("confirm");

    //list box
    List colorList = new List(6, true);

    public void init(){
        //Assembly Bottom
        Box bBox = Box.createHorizontalBox();
        bBox.add(tf);
        bBox.add(ok);
        frame.add(bBox, BorderLayout.SOUTH);

        //Assembly selection section
        colorChooser.add("gules");
        colorChooser.add("blue");
        colorChooser.add("green");
        Box cBox = Box.createHorizontalBox();
        cBox.add(colorChooser);
        cBox.add(male);
        cBox.add(female);
        cBox.add(isMarried);
        frame.add(cBox);

        //Assembling text fields and selection sections
        Box topLeft = Box.createVerticalBox();
        topLeft.add(ta);
        topLeft.add(cBox);
        frame.add(topLeft);

        //Assemble top left and list box
        Box top = Box.createHorizontalBox();
        colorList.add("gules");
        colorList.add("green");
        colorList.add("blue");
        top.add(topLeft);
        top.add(colorList);
        frame.add(top);

        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        BasicComponentDemo bc = new BasicComponentDemo();
        bc.init();
    }
}