java--第11章图形用户界面编程

本是古典何须时尚 2023-01-04 10:29 221阅读 0赞

# **实验内容：** #

![f03cff38b5ad7766814c0998bc7c8f3c.png][]

1.计算圆面积。

2.四则运算器。

# **实验步骤：** #

## 1.计算圆面积。在第一个文本框中输入圆的半径，然后计算此圆面积的值，并将此值放入到第二个文本框中。 ##

源代码：

package homework.实验11_图形用户界面;
    
    import java.awt.Button;
    import java.awt.Frame;
    import java.awt.Label;
    import java.awt.TextField;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.awt.event.WindowAdapter;
    import java.awt.event.WindowEvent;
    
    
    public class Circle extends Frame implements ActionListener {
        private static final long serialVersionUID = 1L;
        static TextField tf1 = new TextField();
        static TextField tf2 = new TextField();
        static Label lab1 = new Label("radius");
        static Button bt = new Button("area");
    
        public static void main(String[] args){
            Circle c = new Circle();
            c.setTitle("求面积");
            c.setLayout(null);
            c.setVisible(true);
            c.setSize(400,400);
            c.add(lab1);
            c.add(bt);
            c.add(tf1);
            c.add(tf2);
            lab1.setBounds(40, 90, 110, 35);
            tf1.setBounds(170, 90, 110, 35);
            bt.setBounds(40, 180, 110, 35);
            tf2.setBounds(170, 180, 110, 35);
            bt.addActionListener(c); //注册事件监听器
            c.addWindowListener(new WindowAdapter(){
                public void windowClosing(WindowEvent e){
                    System.exit(0);
                }
            });  //添加一个监听器，重写windowClosing方法，才能关闭窗口
    
        }
        public void actionPerformed(ActionEvent e){
            int r = Integer.parseInt(tf1.getText());
            float s = (float) ((float)r*r*Math.PI);
            String str = String.valueOf(s);
            tf2.setText(str);
    
        }
    
    }

运行结果截图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4_size_16_color_FFFFFF_t_70][]

## 2.在窗体上创建3个文本框，两个用于输入运算对象，另一个用于存放计算结果，下拉列表框选择四则运算符号。 ##

源代码：

package homework.实验11_图形用户界面;
    
    import java.awt.Button;
    import java.awt.Choice;
    import java.awt.Color;
    import java.awt.FlowLayout;
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.awt.event.ItemEvent;
    import java.awt.event.ItemListener;
    
    import javax.swing.*;
    
    
    public class calculated extends JFrame {
        private static final long serialVersionUID = 1L;
        JTextField num1 = new JTextField();
        JTextField num2 = new JTextField();
        JTextField total = new JTextField();
        static Choice ch = new Choice();
    
        public static void main(String[] args){
            calculated c = new calculated();
            c.setTitle("计算器");
            c.operation();
            c.setBackground(Color.cyan);
            c.setSize(400,300);
            c.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);  //关闭窗口
        }
    
        public void operation(){
            ch.add("+");
            ch.add("-");
            ch.add("*");
            ch.add("/");
            num1.setColumns(5);  //设置此文本框的列数
            num2.setColumns(5);
            total.setColumns(5);
            setLayout(new FlowLayout());  //采用流式布局管理器
            Button bt = new Button("=");
            bt.setBackground(Color.cyan);
            bt.addActionListener(new MyListener(this));  //bt注册事件监听器
            ch.addItemListener(new ChoiceHandler());   //ch注册事件监听器
            add(num1);  //将文本框加入到窗体
            add(ch);
            add(num2);
            add(bt);
            add(total);
            setVisible(true); //设置窗体可见
        }
    
    }
        class MyListener implements ActionListener {
        private calculated mulp;
        public MyListener(calculated mulp){
            this.mulp = mulp;
        }
            @Override
            public void actionPerformed(ActionEvent e) {
                try {
                    String s1 = mulp.num1.getText();
                    String s2 = mulp.num1.getText();
                    int i1 = Integer.parseInt(s1);
                    int i2 = Integer.parseInt(s2);
                    String itm;
                    itm = ChoiceHandler.itml;
                    if(itm.equals("+")){
                        mulp.total.setText(String.valueOf(i1+i2));
                    }else if(itm.equals("-")){
                        mulp.total.setText(String.valueOf(i1-i2));
                    }else if(itm.equals("*")){
                        mulp.total.setText(String.valueOf(i1*i2));
                    }else if(itm.equals("/")){
                        mulp.total.setText(String.valueOf(i1/i2));
                    }
                }catch(Exception e2){
                    JOptionPane.showMessageDialog(null,"除数不能为0");
                }
    
            }
        }
    
    
    class ChoiceHandler implements ItemListener {
        static String itml;
        @Override
        public void itemStateChanged(ItemEvent e) {
            itml = calculated.ch.getSelectedItem();
        }
    }

运行结果截图：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4_size_16_color_FFFFFF_t_70 1][]

# **实验小结** #

swing：在awt的基础上建立的一套图形界面系统，属于Javax扩展包下。其中提供了更多的组件。而且完全由Java实现增强了移植性，属轻量级控件。

GUI API包含的类可以分为三个组:组件类(component class),容器类(container class),辅助类(helper class).它们的体系结构如下:

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4_size_16_color_FFFFFF_t_70 2][]

[f03cff38b5ad7766814c0998bc7c8f3c.png]: /images/20221119/0c3ee7ff0fc74219a150a05cbafeea3a.png
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[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4_size_16_color_FFFFFF_t_70 1]: https://img-blog.csdnimg.cn/20210109162003701.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4,size_16,color_FFFFFF,t_70
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4_size_16_color_FFFFFF_t_70 2]: https://img-blog.csdnimg.cn/20210109162003964.png?x-oss-process=image/watermark,type_ZmFuZ3poZW5naGVpdGk,shadow_10,text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxXzQ1MTc2NTQ4,size_16,color_FFFFFF,t_70