foreword
Let's try to write a piece of code today, write a simple text editor, let's take a look!
First of all, we need to use inheritance (extends) and interface (implements) in Java. We divide it into two files: one file is all the layout and logic; the other file is the most basic frame (JFrame) in the GUI.
In terms of layout, I chose NullLayout, which is convenient but requires more settings.
The components used are: label (JLabel), slider (JSlider), single-line text box (JTextField), multi-line text box (JTextArea), button (JButton), button group (JButtonGroup), radio button (JRadioButton), Font (Font) and prompt box (JDialog).
The event listeners used are: ItemListener, ChangeListener and ActionListener.
Next, let's look at the code together!
import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import javax.swing.*;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class NullLayout extends JFrame implements ItemListener, ChangeListener, ActionListener{
/**
* 设置serialVersionUID属性，防止编译器警告序列化NullLayout没有声明serialVersionUID
*/
private static final long serialVersionUID = 1L;
/**
* @param 这部分为成员变量设置
*/
private JLabel Topjlabel = new JLabel("字体大小");
private JLabel Bottomjlabel = new JLabel("字体颜色");
private JLabel Bottomjlabel2 = new JLabel("滑动标签");
//↓↓↓↓↓↓↓↓这两行顺序不可改变，slider对象应在初始化后调用
private JSlider slider = new JSlider(); //Slider默认最小值0，最大值100，初始值50
private JLabel Bottomcenterjlabel = new JLabel("滑块的值是"+slider.getValue());
//↑↑↑↑↑↑↑↑这两行顺序不可改变，slider对象应在初始化后调用
private JLabel transformtoRGB = new JLabel("十六进制:");
private JLabel useRGB_R = new JLabel("R");
private JLabel useRGB_G = new JLabel("G");
private JLabel useRGB_B = new JLabel("B");
private JLabel prompt = new JLabel(" 请输入7位16进制色彩代码");
private JLabel prompt2 = new JLabel("请输入正确的sRGB色彩(要求RGB在0~255)");
private JTextField R = new JTextField("255",3);
private JTextField G = new JTextField("255",3);
private JTextField B = new JTextField("255",3);
private JTextField jtextfield = new JTextField("#000000",7);
private JButton RGBbutton = new JButton("转换");
private JButton jbtn = new JButton("转换");
private ButtonGroup btngroup = new ButtonGroup();
private ButtonGroup btngroup2 = new ButtonGroup();
private JRadioButton rbt1 = new JRadioButton("小号");
private JRadioButton rbt2 = new JRadioButton("中号");
private JRadioButton rbt3 = new JRadioButton("大号");
private JRadioButton rbt4 = new JRadioButton("红色");
private JRadioButton rbt5 = new JRadioButton("黄色");
private JRadioButton rbt6 = new JRadioButton("蓝色");
private JTextArea textarea = new JTextArea("在此输入文本...",20,20);
private Font f1 = new Font("仿宋",Font.BOLD,25);
private Font f2 = new Font("仿宋",Font.PLAIN,25);
private JDialog jdialog = new JDialog(this,"提示",true);
private JDialog jdialog2 = new JDialog(this,"提示",true);
/**
* @param 成员变量设置完毕
*/
//构造器
public NullLayout(String title){
super(title); //调用父类一参构造器，并初始化JFrame的标题为"简单文本编辑器"。
init(); //为防止构造器内容过多，调用外部函数
}
//构造器内部分，为防止构造器内代码过长，通过调用函数实现
public void init(){
//设置布局为空布局
setLayout(null);
//设置窗口大小不可改变
setResizable(false);
//将字体大小文本加入JPanel
add(Topjlabel);
//设置字体大小组件位置
Topjlabel.setBounds(100, 20, 200, 50);
//设置字体大小组件字体样式
Topjlabel.setFont(f1);
//将字体大小单选按钮加入按钮组
btngroup.add(rbt1);
btngroup.add(rbt2);
btngroup.add(rbt3);
//将字体大小按钮加入JPanel
add(rbt1);
add(rbt2);
add(rbt3);
//设置字体大小按钮的位置
rbt1.setBounds(400, 20, 200, 50);
rbt2.setBounds(600, 20, 200, 50);
rbt3.setBounds(800, 20, 200, 50);
//设置字体大小单选按钮的字体
rbt1.setFont(f1);
rbt2.setFont(f1);
rbt3.setFont(f1);
//将字体大小按钮加入ItemListener监听器
rbt1.addItemListener(this);
rbt2.addItemListener(this);
rbt3.addItemListener(this);
//将多行文本区域加入JPanel
add(textarea);
//设置多行文本区域起始位置
textarea.setBounds(0, 90, 1000, 400);
//设置多行文本区域内的字体
textarea.setFont(f2);
//添加字体颜色组件到JPanel
add(Bottomjlabel);
//设置字体颜色组件位置
Bottomjlabel.setBounds(100, 510, 200, 50);
//设置字体颜色组件的字体
Bottomjlabel.setFont(f1);
//将字体颜色单选按钮加入按钮组
btngroup2.add(rbt4);
btngroup2.add(rbt5);
btngroup2.add(rbt6);
//将字体颜色单选按钮加入JPanel
add(rbt4);
add(rbt5);
add(rbt6);
//设置字体颜色按钮的位置
rbt4.setBounds(400, 510, 200, 50);
rbt5.setBounds(600, 510, 200, 50);
rbt6.setBounds(800, 510, 200, 50);
//设置字体颜色按钮组的字体
rbt4.setFont(f1);
rbt5.setFont(f1);
rbt6.setFont(f1);
//将字体颜色按钮加入ItemListener监听器
rbt4.addItemListener(this);
rbt5.addItemListener(this);
rbt6.addItemListener(this);
//将滑动标签文本加入JPanel
add(Bottomjlabel2);
//设置滑动标签文本位置
Bottomjlabel2.setBounds(100, 580, 150, 50);
//设置滑动标签文本的字体
Bottomjlabel2.setFont(f1);
//将‘滑块的值是’文本加入JPanel
add(Bottomcenterjlabel);
//设置‘滑块的值是’文本位置
Bottomcenterjlabel.setBounds(300, 580, 200, 50);
//设置‘滑块的值是’文本的字体
Bottomcenterjlabel.setFont(f1);
//将滑块加入JPanel
add(slider);
//设置滑块位置
slider.setBounds(550, 580, 300, 50);
//设置滑块主要刻度间距
slider.setMajorTickSpacing(10);
//设置滑块次要刻度间距
slider.setMinorTickSpacing(5);
//绘制滑块标签
slider.setPaintLabels(true);
//绘制滑块刻度标记
slider.setPaintTicks(true);
//绘制滑块滑道
slider.setPaintTrack(true);
//将滑块加入ChangeListener监听器
slider.addChangeListener(this);
//将‘十六进制’文本加入JPanel
add(transformtoRGB);
//设置‘十六进制’文本位置
transformtoRGB.setBounds(100, 650, 150, 50);
//设置‘十六进制’文本字体
transformtoRGB.setFont(f1);
//将十六进制单行文本框加入JPanel
add(jtextfield);
//设置十六进制单行文本框位置
jtextfield.setBounds(250, 650, 120, 50);
//设置十六进制单行文本框字体
jtextfield.setFont(f1);
//将转换按钮加入JPanel
add(jbtn);
//设置转换按钮位置
jbtn.setBounds(400, 650, 100, 50);
//设置转换按钮字体
jbtn.setFont(f1);
//设置转换按钮的事件监听为ActionListener
jbtn.addActionListener(this);
/**将‘R,G,B’加入JPanel
* 设置‘R,G,B’位置
* 设置‘R,G,B'字体
*/
add(useRGB_R);
useRGB_R.setBounds(105, 720, 20, 50);
useRGB_R.setFont(f1);
add(useRGB_G);
useRGB_G.setBounds(250, 720, 20, 50);
useRGB_G.setFont(f1);
add(useRGB_B);
useRGB_B.setBounds(400, 720, 20, 50);
useRGB_B.setFont(f1);
/**将‘R,G,B’文本框加入JPanel
* 设置‘R,G,B’文本框位置
* 设置‘R,G,B’文本框字体
*/
add(R);
R.setBounds(150, 720, 80, 50);
R.setFont(f1);
add(G);
G.setBounds(300, 720, 80, 50);
G.setFont(f1);
add(B);
B.setBounds(450, 720, 80, 50);
B.setFont(f1);
//将转换按钮加入JPanel
add(RGBbutton);
//设置转换按钮位置
RGBbutton.setBounds(550, 720, 100, 50);
//设置转换按钮字体
RGBbutton.setFont(f1);
//设置转换按钮的事件监听为ActionListener
RGBbutton.addActionListener(this);
jdialog.setSize(500,250);
Container con = jdialog.getContentPane();
prompt.setFont(f1);
con.add(prompt);
jdialog2.setSize(500,250);
Container con2 = jdialog2.getContentPane();
prompt2.setFont(f1);
con2.add(prompt2);
}
//事件监听函数，用于监听单选按钮的发生
public void itemStateChanged(ItemEvent e){
int size = 25;
if (rbt1.isSelected()){ //设置文字大小为10
size = 10;
}
if (rbt2.isSelected()){ //设置文字大小为30
size = 30;
}
if (rbt3.isSelected()){ //设置文字大小为50
size = 50;
}
if(rbt4.isSelected()){
textarea.setForeground(Color.RED); //设置文字前景色（文字颜色）为红色
}
if(rbt5.isSelected()){
textarea.setForeground(Color.YELLOW); //设置文字前景色（文字颜色）为黄色
}
if(rbt6.isSelected()){
textarea.setForeground(Color.BLUE); //设置文字前景色（文字颜色）为蓝色
}
//设置多行文本区域文字大小为size
Font font = new Font("仿宋", Font.PLAIN, size);
textarea.setFont(font);
}
//事件监听函数，用于监听滑块动作，并更改字体大小以及数字显示
public void stateChanged(ChangeEvent e){
if(e.getSource() == slider){
//更改数字显示
Bottomcenterjlabel.setText("滑块的值是"+slider.getValue());
//更改字体大小
Font font = new Font("仿宋",Font.PLAIN,slider.getValue());
textarea.setFont(font);
}
}
//动作事件
public void actionPerformed(ActionEvent e){
/**触发按钮jbtn时更改文字前景颜色
* (transform16To_R/G/B为十六进制转sRGB函数)
*/
if(e.getSource() == jbtn){
if(jtextfield.getText().length() == 7){
Color color = new Color(transform16To_R(jtextfield.getText()),transform16To_G(jtextfield.getText()),transform16To_B(jtextfield.getText()));
textarea.setForeground(color);
}else{
/**此处十六进制代码只需判断JTextField中得到的字符串长度为7。
* 满足：返回字体颜色；不满足：返回弹窗
*/
jdialog.setLocation(550,350); //设置弹窗位置
jdialog.setVisible(true); //设置弹窗是否可见
}
}
if(e.getSource() == RGBbutton){
/**此处sRGB值需要判断每个JTextField是否为0~255之间的值。
* 满足：返回字体颜色；不满足：返回弹窗
*/
if((Integer.parseInt(R.getText())>=0 && Integer.parseInt(R.getText())<=255)&&(Integer.parseInt(G.getText())>=0 && Integer.parseInt(G.getText())<=255)&&(Integer.parseInt(B.getText())>=0 && Integer.parseInt(B.getText())<=255)){
Color color = new Color(Integer.parseInt(R.getText()),Integer.parseInt(G.getText()),Integer.parseInt(B.getText()));
textarea.setForeground(color);
}else{
jdialog2.setLocation(550,350); //设置弹窗位置
jdialog2.setVisible(true); //设置弹窗是否可见
}
}
}
//十六进制转R
public int transform16To_R(String RGB){
if(RGB != null && !"".equals(RGB) && RGB.length() == 7){
//截取十六进制字符串第1,2位，并将其转换为sRGB中R型整数
int R = Integer.valueOf(RGB.substring( 1, 3 ), 16);
//返回R型整数
return R;
}
return 0;
}
//十六进制转G
public int transform16To_G(String RGB){
if(RGB != null && !"".equals(RGB) && RGB.length() == 7){
//截取十六进制字符串第3,4位，并将其转换为sRGB中G型整数
int G = Integer.valueOf(RGB.substring( 3, 5 ), 16);
//返回G型整数
return G;
}
return 0;
}
//十六进制转B
public int transform16To_B(String RGB){
if(RGB != null && !"".equals(RGB) && RGB.length() == 7){
//截取十六进制字符串第5，6位，并将其转换为sRGB中B型整数
int B = Integer.valueOf(RGB.substring( 5, 7 ), 16);
//返回B型整数
return B;
}
return 0;
}
}
The following is the main function part:
import javax.swing.*;
public class Main {
public static void main(String[] args) {
NullLayout frame = new NullLayout("简单文本编辑器");
frame.setLocation(300, 50); //设置JFrame窗体位置
frame.setSize(1000, 850); //设置JFrame窗体大小
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //设置JFrame窗体关闭时为直接结束程序进程
frame.setVisible(true); //设置JFrame窗体是否可见，默认false
}
}
Finally, show the results of the code operation!
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Good article recommendation
Understand the prospect of python: https://blog.csdn.net/SpringJavaMyBatis/article/details/127194835
Learn about python's part-time sideline: https://blog.csdn.net/SpringJavaMyBatis/article/details/127196603