java - 使用图形的语法错误

Question

我使用下面的代码将两个 PNG 合并在一起，尽管在以 g.drawImage 开头的两行上都出现语法错误。这来自 Merging two images 的示例但我不能对此发表评论，因为我刚刚在这里注册。

package imageEditor;

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

public class ImageEditor15092703 {
    File path = new File("C:/Users/Colton/Desktop/JavaImageEditor/"); // base path of the images

    // load source images
    BufferedImage image = ImageIO.read(new File(path, "image.png"));
    BufferedImage overlay = ImageIO.read(new File(path, "overlay.png"));

    // create the new image, canvas size is the max. of both image sizes
    int w = Math.max(image.getWidth(), overlay.getWidth());
    int h = Math.max(image.getHeight(), overlay.getHeight());
    BufferedImage combined = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

    // paint both images, preserving the alpha channels
    Graphics g = combined.getGraphics();
    g.drawImage(image, 0, 0, null);
    g.drawImage(overlay, 0, 0, null);

    // Save as new image
    ImageIO.write(combined, "PNG", new File(path, "combined.png"));
}

谢谢

编辑

到目前为止，我通过制定方法和异常得到了进一步的帮助。它现在可以编译并运行，但不会创建新的 png 文件。我觉得抛出了异常，导致程序无法执行其应该执行的操作。

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

public class ImageEditor15092705{

    public void ImageEditor15092705() throws IOException{
        File path = new File("C:/Users/Colton/Desktop/JavaImageEditor/"); // base path of the images

        // load source images
        BufferedImage image = ImageIO.read(new File(path, "image.png"));
        BufferedImage overlay = ImageIO.read(new File(path, "overlay.png"));

        // create the new image, canvas size is the max. of both image sizes
        int w = Math.max(image.getWidth(), overlay.getWidth());
        int h = Math.max(image.getHeight(), overlay.getHeight());
        BufferedImage combined = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

        // paint both images, preserving the alpha channels
        Graphics g = combined.getGraphics();
        g.drawImage(image, 0, 0, null);
        g.drawImage(overlay, 0, 0, null);

        // Save as new image
        ImageIO.write(combined, "PNG", new File(path, "combined.png"));
    }

    public static void main (String[] args)
   {
   ImageEditor15092705 foo = new ImageEditor15092705();
   }//end main

} //end image editor class

Answer 1

出现此错误是因为您应该在方法中编写语句，而不是类。你看，你创建了一个类，并且你立即在类中编写语句。您应该在方法中编写语句，并且某些语句会抛出异常，因此您应该添加 throw IOException，如下所示；

public static void mergeImage (String p_basePath, String p_image, String p_overlay) throws IOException {
    File path = new File(p_basePath); // base path of the images

    // load source images
    BufferedImage image = ImageIO.read(new File(path, p_image));
    BufferedImage overlay = ImageIO.read(new File(path, p_overlay));

    // create the new image, canvas size is the max. of both image sizes
    int w = Math.max(image.getWidth(), overlay.getWidth());
    int h = Math.max(image.getHeight(), overlay.getHeight());
    BufferedImage combined = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

    // paint both images, preserving the alpha channels
    Graphics g = combined.getGraphics();
    g.drawImage(image, 0, 0, null);
    g.drawImage(overlay, 0, 0, null);

    // Save as new image
    ImageIO.write(combined, "PNG", new File(path, "combined.png"));
}

或者您可以添加参数:

public static void mergeImage () throws IOException {
    File path = new File("C:/Users/Colton/Desktop/JavaImageEditor/"); // base path of the images

    // load source images
    BufferedImage image = ImageIO.read(new File(path, "image.png"));
    BufferedImage overlay = ImageIO.read(new File(path, "overlay.png"));

    // create the new image, canvas size is the max. of both image sizes
    int w = Math.max(image.getWidth(), overlay.getWidth());
    int h = Math.max(image.getHeight(), overlay.getHeight());
    BufferedImage combined = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

    // paint both images, preserving the alpha channels
    Graphics g = combined.getGraphics();
    g.drawImage(image, 0, 0, null);
    g.drawImage(overlay, 0, 0, null);

    // Save as new image
    ImageIO.write(combined, "PNG", new File(path, "combined.png"));
}

下次，请记住，始终在方法或构造函数中编写语句，并注意某些方法可能抛出的异常。