我有幾個java文件。Main.java使用文件中的Picture類Picture.java。我想知道如何從命令行編譯和運行 Main ？這是Main.java：package com.company;import javax.imageio.ImageIO;import java.awt.*;import java.awt.image.BufferedImage;import java.io.File;import java.io.IOException;public class Main {    static Picture pic = null; // Picture class ???    public static void main(String[] args) {        long t1, t2;        String name = "bears.jpg";        pic = new Picture(name);        t1 = System.nanoTime();        pic.new_img = meanFilter(pic.img);        t2 = System.nanoTime();        pic.writeImage();        calculateTime(t1, t2);    }和Picture.java：...public class Picture {    public BufferedImage img;    public BufferedImage new_img;    ...