AWT common components, FileDialog file selection box

Recommended reading ：Java Detailed explanation of graphical interface (AWT、Swing) special column

Common components

Component name	function
Button	Button
Canvas	A canvas for drawing
Checkbox	Check box components （ It can also be used as a radio box component ）
CheckboxGroup	Used to transfer multiple Checkbox Components are assembled into a group , A group of Checkbox There will be only one component that can To be selected , That is to say, they all become radio box components
Choice	Drop down the selection box
Frame	window , stay GUI Program through this class to create a window
Label	The tag class , Used to place suggestive text
List	JU Frame components , You can add multiple entries
Panel	Basic container classes cannot exist alone , It has to be put in another container
Scrollbar	Slide bar component . If the user is required to enter a value in a range , You can use the slider component , For example, tune Set... In the palette RGB The slider used for the three values of . When you create a slider , You have to specify its direction 、 Initial value 、 The size of the slider 、 Min and Max .
ScrollPane	Container components with horizontal and vertical scrollbars
TextArea	Multiline text field
TextField	Single line text box

these AWT The usage of component is relatively simple , You can refer to API Documents to get their respective construction methods 、 Details such as member methods .

Code example

import javax.swing.*;
import java.awt.*;

public class BasicComponentDemo {
    
    Frame frame = new Frame(" Here we test the basic components ");

    // Define a button 
    Button ok = new Button(" confirm ");

    // Define a check box group 
    CheckboxGroup cbg = new CheckboxGroup();
    // Define a radio box , Initially in the selected state , To add to cbg In the group 
    Checkbox male = new Checkbox(" male ", cbg, true);

    // Define a radio box , Initially in the unselected state , To add to cbg In the group 
    Checkbox female = new Checkbox(" Woman ", cbg, false);

    // Define a check box , Initially in the unselected state 
    Checkbox married = new Checkbox(" Married or not ？", false);

    // Define a drop-down selection box 
    Choice colorChooser = new Choice();

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

    // Define a 5 That's ok ,20 The multiline text field of the column 
    TextArea ta = new TextArea(5, 20);

    // Define a 50 The single line text field of the column 
    TextField tf = new TextField(50);

    public void init() {
    
        // Pull down the selection box to add content 
        colorChooser.add(" Red ");
        colorChooser.add(" green ");
        colorChooser.add(" Blue ");

        // Add content to the list selection box 
        colorList.add(" Red ");
        colorList.add(" green ");
        colorList.add(" Blue ");

        // Create a load button and text box Panel Containers 
        Panel bottom = new Panel();
        bottom.add(tf);
        bottom.add(ok);

        // hold bottom Add to Frame The bottom of 
        frame.add(bottom,BorderLayout.SOUTH);

        // Create a Panel Containers , Load drop-down selection box , Radio and check boxes 
        Panel checkPanel = new Panel();
        checkPanel.add(colorChooser);
        checkPanel.add(male);
        checkPanel.add(female);
        checkPanel.add(married);

        // Create a vertically arranged Box Containers , load   Multiline text fields and checkPanel
        Box topLeft = Box.createVerticalBox();
        topLeft.add(ta);
        topLeft.add(checkPanel);

        // Create a horizontally arranged Box Containers , load topLeft And list selection box 
        Box top = Box.createHorizontalBox();
        top.add(topLeft);
        top.add(colorList);

        // take top Add to frame In the middle of 
        frame.add(top);


        // Set up frame Best size and visible 
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
    

        new BasicComponentDemo().init();

    }
}

Dialog Dialog box

Concept 、 Method

Dialog yes Window Subclasses of classes , yes A container class , It belongs to a special component . Dialog box is a top-level window that can exist independently , Therefore, the usage is almost the same as that of ordinary windows , However, you need to pay attention to the following two points when using the dialog box ：

1. Dialog boxes usually depend on other windows , It is usually necessary to have a parent window ;
2. Dialog box has non mode (non-modal) And pattern (modal) Two kinds of , When a mode dialog is opened , The modal dialog is always above its parent window , Before the Mode dialog is closed , The parent window cannot get focus ;

Method name	Method function
Dialog(Frame owner, String title, boolean modal)	Create a dialog object ： owner: The parent window of the current dialog title: The title of the current dialog modal： Whether the current dialog is a modal dialog ,true/false

Code example

adopt Frame、Button、Dialog Achieve the following effect :

import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class DialogDemo1 {
    

    public static void main(String[] args) {
    

        Frame frame = new Frame(" Test here Dialog");

        Dialog d1 = new Dialog(frame, " Mode dialog ", true);
        Dialog d2 = new Dialog(frame, " Non modal dialog ", false);

        Button b1 = new Button(" Open the Mode dialog ");
        Button b2 = new Button(" Open the modeless dialog box ");

        // Set the size and location of the dialog box 
        d1.setBounds(20,30,300,400);
        d2.setBounds(20,30,300,400);

        // to b1 and b2 Bind listening event 
        b1.addActionListener(new ActionListener() {
    
            @Override
            public void actionPerformed(ActionEvent e) {
    
                d1.setVisible(true);
            }
        });
        b2.addActionListener(new ActionListener() {
    
            @Override
            public void actionPerformed(ActionEvent e) {
    
                d2.setVisible(true);
            }
        });

        // Add a button to frame in 
        frame.add(b1);
        frame.add(b2,BorderLayout.SOUTH);

        // Set up frame Best size and visible 
        frame.pack();
        frame.setVisible(true);

    }
}

FileDialog Dialog box

summary 、 Method

Dialog Class and A subclass : FileDialog , It represents a file dialog , Used to open or save file , It should be noted that FileDialog Cannot specify modal or modeless , This is because FileDialog Depending on the implementation of the running platform , If the running platform's file dialog is modal , that FileDialog It's also modal ; Otherwise, it's non modal .

Method name	Method function
FileDialog(Frame parent, String title, int mode)	Create a file dialog ： parent: Specify the parent window title: Dialog title mode: File dialog type , If specified as FileDialog.load, Used to open a file , If specified as FileDialog.SAVE, Used to save files
String getDirectory()	Get the absolute path of the opened or saved file
String getFile()	Get the file name of the opened or saved file

Code example

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

public class FileDialogTest {
    

    public static void main(String[] args) {
    

        Frame frame = new Frame(" Test here FileDialog");

        FileDialog d1 = new FileDialog(frame, " Select the file to load ", FileDialog.LOAD);
        FileDialog d2 = new FileDialog(frame, " Select the file to save ", FileDialog.SAVE);

        Button b1 = new Button(" Open file ");
        Button b2 = new Button(" Save the file ");

        // Add events to the button 
        b1.addActionListener(new ActionListener() {
    
            @Override
            public void actionPerformed(ActionEvent e) {
    
                d1.setVisible(true);
                // Print the file path and name selected by the user 
                System.out.println(" User selected file path :"+d1.getDirectory());
                System.out.println(" File name selected by the user :"+d1.getFile());
            }
        });

        System.out.println("-------------------------------");
        b2.addActionListener(new ActionListener() {
    
            @Override
            public void actionPerformed(ActionEvent e) {
    
                d2.setVisible(true);
                // Print the file path and name selected by the user 
                System.out.println(" User selected file path :"+d2.getDirectory());
                System.out.println(" File name selected by the user :"+d2.getFile());
            }
        });

        // Add button to frame in 

        frame.add(b1);
        frame.add(b2,BorderLayout.SOUTH);

        // Set up frame Best size and visible 
        frame.pack();
        frame.setVisible(true);
    }
}

Recommended reading ：Java Detailed explanation of graphical interface (AWT、Swing) special column