线程“main”中的异常java.lang.IndexOutOfBoundsException [英] Exception in thread "main" java.lang.IndexOutOfBoundsException

问题描述

我正在尝试获取特定像素兴趣点的rgb值

  （< span class =code-keyword> int  i =  0 ; i< = locations_original.size（）; i ++）
 {
 
 System.out.println（  x，y： + locations_original。 get（i）.x +  ， + 
 locations_original.get（i）。 Y）; 
 Double x = locations_original.get（i）.x; 
 Double y = locations_original.get（i）.y; 
  int  pixel = image.getRGB（x.intValue（），y.intValue（））; 
 printPixelARGB（pixel）; 
} 
 

  public   static   void  printPixelARGB（ int  pixel）{
  int  alpha =（pixel>>  24 ）& 0xFF的; 
  int  red =（pixel>>  16 ）& 0xFF的; 
  int  green =（pixel>>  8 ）& 0xFF的; 
  int  blue =（pixel）& 0xFF的; 
 System.out.println（  argb： + alpha +  ， + red +  ， + green +  ，
 + blue ）; 
} 
 

但此行中有错误

 System.out.println（  x，y： + locations_original.get （i）.x +  ， + locations_original.get（i）.y）; 

引用：

如下

线程中的异常  main java.lang.IndexOutOfBoundsException ：索引： 8 ，大小： 8  
 at java.util.ArrayList.rangeCheck（Unknown来源）
 at java.util.ArrayList.get（未知来源）
 at boofcv.ExampleInterestPoint.main（ExampleInterestPoint.java： 555 ）

我该如何解决这个问题？



问候！

解决方案

最有可能的是，

  （ int  i =  0 ; i< = locations_original.size（）; i ++）

应替换为

  for （ int  i =  0 ; i< locations_original.size（）; i ++）

我甚至要解释原因吗？这是小学数学;大多数开发人员从第一眼看到这个错误，在反应水平，因为正确的代码是一个非常常见的模式：N个元素的范围从0到N-1索引。

-SA

循环初始化出现问题....

它应该像....

  for （ int  i =  0 ; i< locations_original.size（）; i ++）{...} 

I am trying to get rgb values for specific pixels "interest points"

for (int i = 0; i <=locations_original.size();i++)
 {

     System.out.println("x,y: " + locations_original.get(i).x + ", " +
     locations_original.get(i).y);
     Double x=locations_original.get(i).x;
     Double y=locations_original.get(i).y;
     int pixel = image.getRGB(x.intValue(),y.intValue());
     printPixelARGB(pixel);
 }

 public static void printPixelARGB(int pixel) {
     int alpha = (pixel >> 24) & 0xff;
     int red = (pixel >> 16) & 0xff;
     int green = (pixel >> 8) & 0xff;
     int blue = (pixel) & 0xff;
     System.out.println("argb: " + alpha + ", " + red + ", " + green + ",
     " + blue);
}

but there is an error in this line

System.out.println("x,y: " + locations_original.get(i).x + ", " +locations_original.get(i).y);

Quote:

as following

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 8, Size: 8
	at java.util.ArrayList.rangeCheck(Unknown Source)
	at java.util.ArrayList.get(Unknown Source)
	at boofcv.ExampleInterestPoint.main(ExampleInterestPoint.java:555)

How can I fix this?

Regards!

解决方案

Most likely, the line

for (int i = 0; i <= locations_original.size(); i++)

should be replaced with

for (int i = 0; i < locations_original.size(); i++)

Do I even have to explain why? This is elementary mathematics; and most developers catch this bug from the first glance, at the level of reflexes, because right code is a very common pattern: a range of N elements is indexed from 0 to N−1.

—SA

there is a problem in your loop initialization ....
it should be like ....

for (int i = 0; i <locations_original.size();i++){...}

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