3、由多个类组成的Java程序的编写与运行； （1）在FirstProgram.java中添加以下代码； public class Another{ public void say(){ System.out.println("Another one."); } } （2）使用javac命令编译程序，并根据出现的提示信息修改程序直至程序编译正确为止； （3）使用java命令运行程序，并根据出现的提示信息修改程序直至程序运行正确为止。 （4）请修改程序，使用Another类，使得“Another one”能够正常输出。

修改后的程序如下：

public class FirstProgram {
    public static void main(String[] args) {
        Another another = new Another();
        another.say();
    }
}

class Another {
    public void say() {
        System.out.println("Another one.");
    }
}

编译程序的命令为：`javac FirstProgram.java`

运行程序的命令为：`java FirstProgram`

运行正确后，输出结果为：`Another one.`

相关问题

实验任务1、2、3、4、5的JAVA运行代码

由于引用内容较多，无法在此直接提供完整的JAVA运行代码，建议参考引用中提供的实验报告模板及示例代码进行编写。以下是对每个实验任务的简要描述和相关参考代码：

实验任务1：设计一个GUI应用程序，窗口标题为“First GUI Program”，窗口大小为（500，300），窗口背景色为红色，居中显示。参考代码如下：

import javax.swing.*;

public class FirstGUIProgram extends JFrame {
    public FirstGUIProgram() {
        setSize(500, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("First GUI Program");
        getContentPane().setBackground(Color.RED);
        setLocationRelativeTo(null);
    }

    public static void main(String[] args) {
        FirstGUIProgram frame = new FirstGUIProgram();
        frame.setVisible(true);
    }
}

实验任务2：在实验任务1的基础上，响应按钮事件。当用户点击“green”按钮时，修改背景色为绿色。参考代码如下：

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

public class FirstGUIProgram extends JFrame implements ActionListener {
    private JButton btnGreen;

    public FirstGUIProgram() {
        setSize(500, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("First GUI Program");
        getContentPane().setBackground(Color.RED);
        setLocationRelativeTo(null);

        JPanel panel = new JPanel();
        getContentPane().add(panel, BorderLayout.SOUTH);

        btnGreen = new JButton("green");
        btnGreen.addActionListener(this);
        panel.add(btnGreen);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnGreen) {
            getContentPane().setBackground(Color.GREEN);
        }
    }

    public static void main(String[] args) {
        FirstGUIProgram frame = new FirstGUIProgram();
        frame.setVisible(true);
    }
}

实验任务3：在实验任务2的基础上，添加一个按钮，当用户点击“reset”按钮时，将背景色还原为红色。参考代码如下：

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

public class FirstGUIProgram extends JFrame implements ActionListener {
    private JButton btnGreen;
    private JButton btnReset;

    public FirstGUIProgram() {
        setSize(500, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("First GUI Program");
        getContentPane().setBackground(Color.RED);
        setLocationRelativeTo(null);

        JPanel panel = new JPanel();
        getContentPane().add(panel, BorderLayout.SOUTH);

        btnGreen = new JButton("green");
        btnGreen.addActionListener(this);
        panel.add(btnGreen);

        btnReset = new JButton("reset");
        btnReset.addActionListener(this);
        panel.add(btnReset);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnGreen) {
            getContentPane().setBackground(Color.GREEN);
        } else if (e.getSource() == btnReset) {
            getContentPane().setBackground(Color.RED);
        }
    }

    public static void main(String[] args) {
        FirstGUIProgram frame = new FirstGUIProgram();
        frame.setVisible(true);
    }
}

实验任务4：在实验任务3的基础上，添加两个文本框和两个标签，分别用于输入长和宽，并显示面积和周长。参考代码如下：

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

public class FirstGUIProgram extends JFrame implements ActionListener {
    private JButton btnGreen;
    private JButton btnReset;
    private JLabel lblLength;
    private JLabel lblWidth;
    private JTextField txtLength;
    private JTextField txtWidth;
    private JLabel lblArea;
    private JLabel lblPerimeter;

    public FirstGUIProgram() {
        setSize(500, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("First GUI Program");
        getContentPane().setBackground(Color.RED);
        setLocationRelativeTo(null);

        JPanel panel = new JPanel();
        getContentPane().add(panel, BorderLayout.SOUTH);

        btnGreen = new JButton("green");
        btnGreen.addActionListener(this);
        panel.add(btnGreen);

        btnReset = new JButton("reset");
        btnReset.addActionListener(this);
        panel.add(btnReset);

        JPanel centerPanel = new JPanel(new GridLayout(3, 2));
        getContentPane().add(centerPanel, BorderLayout.CENTER);

        lblLength = new JLabel("Length:");
        centerPanel.add(lblLength);

        txtLength = new JTextField();
        centerPanel.add(txtLength);

        lblWidth = new JLabel("Width:");
        centerPanel.add(lblWidth);

        txtWidth = new JTextField();
        centerPanel.add(txtWidth);

        JLabel lblAreaTitle = new JLabel("Area:");
        centerPanel.add(lblAreaTitle);

        lblArea = new JLabel();
        centerPanel.add(lblArea);

        JLabel lblPerimeterTitle = new JLabel("Perimeter:");
        centerPanel.add(lblPerimeterTitle);

        lblPerimeter = new JLabel();
        centerPanel.add(lblPerimeter);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnGreen) {
            getContentPane().setBackground(Color.GREEN);
        } else if (e.getSource() == btnReset) {
            getContentPane().setBackground(Color.RED);
        }

        if (txtLength.getText().isEmpty() || txtWidth.getText().isEmpty()) {
            lblArea.setText("");
            lblPerimeter.setText("");
            return;
        }

        double length = Double.parseDouble(txtLength.getText());
        double width = Double.parseDouble(txtWidth.getText());

        Rectangle rectangle = new Rectangle(length, width);

        lblArea.setText(Double.toString(rectangle.getArea()));
        lblPerimeter.setText(Double.toString(rectangle.getPerimeter()));
    }

    public static void main(String[] args) {
        FirstGUIProgram frame = new FirstGUIProgram();
        frame.setVisible(true);
    }
}

class Rectangle {
    private double length;
    private double width;

    public Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }

    public double getLength() {
        return length;
    }

    public double getWidth() {
        return width;
    }

    public double getArea() {
        return length * width;
    }

    public double getPerimeter() {
        return 2 * (length + width);
    }
}

实验任务5：在实验任务4的基础上，添加一个按钮，当用户点击“red”按钮时，将背景色变为红色，并清空所有文本框和标签。参考代码如下：

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

public class FirstGUIProgram extends JFrame implements ActionListener {
    private JButton btnGreen;
    private JButton btnReset;
    private JButton btnRed;
    private JLabel lblLength;
    private JLabel lblWidth;
    private JTextField txtLength;
    private JTextField txtWidth;
    private JLabel lblArea;
    private JLabel lblPerimeter;

    public FirstGUIProgram() {
        setSize(500, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("First GUI Program");
        getContentPane().setBackground(Color.RED);
        setLocationRelativeTo(null);

        JPanel panel = new JPanel();
        getContentPane().add(panel, BorderLayout.SOUTH);

        btnGreen = new JButton("green");
        btnGreen.addActionListener(this);
        panel.add(btnGreen);

        btnReset = new JButton("reset");
        btnReset.addActionListener(this);
        panel.add(btnReset);

        btnRed = new JButton("red");
        btnRed.addActionListener(this);
        panel.add(btnRed);

        JPanel centerPanel = new JPanel(new GridLayout(3, 2));
        getContentPane().add(centerPanel, BorderLayout.CENTER);

        lblLength = new JLabel("Length:");
        centerPanel.add(lblLength);

        txtLength = new JTextField();
        centerPanel.add(txtLength);

        lblWidth = new JLabel("Width:");
        centerPanel.add(lblWidth);

        txtWidth = new JTextField();
        centerPanel.add(txtWidth);

        JLabel lblAreaTitle = new JLabel("Area:");
        centerPanel.add(lblAreaTitle);

        lblArea = new JLabel();
        centerPanel.add(lblArea);

        JLabel lblPerimeterTitle = new JLabel("Perimeter:");
        centerPanel.add(lblPerimeterTitle);

        lblPerimeter = new JLabel();
        centerPanel.add(lblPerimeter);
    }

    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == btnGreen) {
            getContentPane().setBackground(Color.GREEN);
        } else if (e.getSource() == btnReset) {
            getContentPane().setBackground(Color.RED);
            txtLength.setText("");
            txtWidth.setText("");
            lblArea.setText("");
            lblPerimeter.setText("");
        } else if (e.getSource() == btnRed) {
            getContentPane().setBackground(Color.RED);
            txtLength.setText("");
            txtWidth.setText("");
            lblArea.setText("");
            lblPerimeter.setText("");
        }

        if (txtLength.getText().isEmpty() || txtWidth.getText().isEmpty()) {
            lblArea.setText("");
            lblPerimeter.setText("");
            return;
        }

        double length = Double.parseDouble(txtLength.getText());
        double width = Double.parseDouble(txtWidth.getText());

        Rectangle rectangle = new Rectangle(length, width);

        lblArea.setText(Double.toString(rectangle.getArea()));
        lblPerimeter.setText(Double.toString(rectangle.getPerimeter()));
    }

    public static void main(String[] args) {
        FirstGUIProgram frame = new FirstGUIProgram();
        frame.setVisible(true);
    }
}

class Rectangle {
    private double length;
    private double width;

    public Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }

    public double getLength() {
        return length;
    }

    public double getWidth() {
        return width;
    }

    public double getArea() {
        return length * width;
    }

    public double getPerimeter() {
        return 2 * (length + width);
    }
}