Question

我真的不明白这一点。当我在Eclipse中运行我的程序时，它看起来非常好。它出现在下面：

（请注意，我拖了一些东西来掩盖我的全名，因为这个程序是为学校项目编写的。请忽略它）。请注意，一切都显示

然而，当我在eclipse之外运行程序时......

Chemistry program when run from outside of Eclipse

正如您所看到的，任何与PaintComponent相关的对象都不会显示，但JText和JButton的所有其他对象都会显示出来。 JOptionPane消息框也会显示出来。值得注意的是，一切看起来都不是全部来自一个JPanel，它不包含任何显示的内容。

以下是未出现的Panel代码：

package gui;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Image;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JPanel;

public class TopPane extends JPanel {
    public TopPane(){
        setLayout(new FlowLayout());
    }

    public void paintComponent(Graphics g){
        try{
        String filename = "logo.jpg";
        Image image = ImageIO.read(new File(filename));
        g.drawImage(image, 45, -10, null);

        String intro = "Program by XXXXXXX XXXX\n";
        String intro2 = "The purpose of this program is to make the process of creating a solution";
        String intro3 = "less painful by performing the calculations for how much solute needs to be\n";
        String intro4 = "added to the solvent.  Miscellanious additional information will also be provided.\n";
        String intro5 = "\n";
        String intro6 = "Please enter infromation in the following format:\n";
        String intro7 = "<volume> <molarity> <compound>\n";
        String intro8 = "For example:";
        String intro9 = "5mL 5M H2SO4";
        g.drawString(intro, 30, 70);
        g.drawString(intro2, 30, 95);
        g.drawString(intro3, 30, 110);
        g.drawString(intro4, 30, 125);
        g.drawString(intro5, 30, 140);
        g.drawString(intro6, 30, 155);
        g.drawString(intro7, 30, 170);
        g.drawString(intro8, 30, 195);
        g.drawString(intro9, 30, 210);
        }catch(Exception ex){System.out.println("Failed");}
    }
}

以下是运行该类的类的代码示例，该类在eclipse之外运行时不起作用：

package gui;
import java.awt.BorderLayout;
import javax.swing.JFrame;

public class MainFrame extends JFrame{
    public MainFrame(){
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setTitle("Chemistry Lab Assistant");
        setSize(550, 300);

        //Top Frame
        TopPane topPane = new TopPane();
        add(topPane);

        //Input Pane
        InputPane inputPane = new InputPane();
        add(inputPane, BorderLayout.SOUTH);
    }
}

Answer 1

请勿尝试使用paintComponent()方法读取图片！

更重要的是，到部署时，这些资源可能会成为embedded-resource。在这种情况下，必须由URL而不是File访问资源。有关标记的info page，请参阅URL。

进一步提示：

g.drawImage(image, 45, -10, null);最好是g.drawImage(image, 45, -10, this);
将表单catch (Exception e) { ..的代码更改为catch (Exception e) { e.printStackTrace(); // very informative! ..
不要设置顶级容器的大小。而是布局内容＆amp;致电pack()。

Paint组件在Eclipse外部不起作用

1 个答案:

进一步提示：