为什么不显示我的照片？ [英] Why not show my picture ?

问题描述

我尝试在java算法中实现旋转图像，但它不显示我的图片。你能帮我吗，请检查图像轮换的代码是否正确。

这是我的代码：

谢谢



我尝试过：

I try to implement in java algorithm for rotate a image, but it's not show my picture. Can you help me, please check if the code for image rotation is right.
This is my code:
Thanks

What I have tried:

import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;

public class Rotation extends JPanel{
	
	public static void main(String []args){
		JFrame f = new JFrame();
		f.add(new Rotation());
		f.setSize(750, 600);
		f.setVisible(true);
		f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		BufferedImage img = null;
		try {
		    img = ImageIO.read(new File("img.jpg"));
		} catch (IOException e) {
			e.printStackTrace();
		}
		Rotation r = new Rotation();
		r.rotateCw(img, null);
	}
	
	public static void rotateCw( BufferedImage img, Graphics g )
	{
	    int         width  = img.getWidth();
	    int         height = img.getHeight();
	    BufferedImage   newImage = new BufferedImage( height, width, img.getType() );
	 
	    for( int i=0 ; i < width ; i++ ){
	        for( int j=0 ; j < height ; j++ ){
	            newImage.setRGB( height-1-j, i, img.getRGB(i,j) );;
	        }
	    }
		Graphics2D g2d = (Graphics2D) g;
		
		g2d.drawImage(newImage, 25, 25, null);
	}
}

推荐答案

通过使用调试器，您可以通过验证零件来缩小研究范围您的代码。



当您不理解您的代码正在做什么或为什么它做它的作用时，答案是调试器 。

使用调试器查看代码正在执行的操作。只需设置断点并查看代码执行情况，调试器允许您逐行执行第1行并在执行时检查变量，这是一个令人难以置信的学习工具。



调试器 - 维基百科，免费的百科全书 [ ^ ]

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https://www.jetbrains.com/idea/help/debugging-your-first-java -application.html [ ^ ]



调试器在这里向您展示您的代码正在做什么，您的任务是与它应该做什么进行比较。

调试器中没有魔法，它没有找到错误，它只是帮助你。当代码没有达到预期的效果时，你就会接近一个错误。

By using the debugger, you will be able to narrow the research by validating parts of your code.

When you don't understand what your code is doing or why it does what it does, the answer is debugger.
Use the debugger to see what your code is doing. Just set a breakpoint and see your code performing, the debugger allow you to execute lines 1 by 1 and to inspect variables as it execute, it is an incredible learning tool.

Debugger - Wikipedia, the free encyclopedia[^]
http://docs.oracle.com/javase/7/docs/technotes/tools/windows/jdb.html[^]
https://www.jetbrains.com/idea/help/debugging-your-first-java-application.html[^]

The debugger is here to show you what your code is doing and your task is to compare with what it should do.
There is no magic in the debugger, it don't find bugs, it just help you to. When the code don't do what is expected, you are close to a bug.

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