java中的Arrays.copyOfRange方法抛出不正确的异常

问题描述

如果你看下面的代码，我认为它必须抛出$ code> ArrayIndexOutOfBoundsException ，但令人惊讶的是它是抛出 IllegalArgumentException 而是：

  import java.util.Arrays; 
 public class RangeTest {
 public static void main（String [] args）{
 int [] a = new int [] {0,1,2,3,4,5,6 ，7,8,9-}; 
 int [] b = Arrays.copyOfRange（a，Integer.MIN_VALUE，10）; 
 //如果我们将使用Integer.MIN_VALUE + 100替代Integer.MIN_VALUE，
 // OutOfMemoryError将抛出
（int k = 0; k  System.out.print（b [k] +）; 
} 
} 
  

有人可以帮助我，让我知道，如果我是错误？

解决方案

嗯，Javadoc说：

看看实现，你可以看到你有一个 IllegalArgumentException exception而不是 ArrayIndexOutOfBoundsException 由于 int overflow：

  public static int [] copyOfRange（int [] original，int from，int to）{
 int newLength = to  -  from; 
 if（newLength< 0）
 throw new IllegalArgumentException（from +>+ to）; 
 int [] copy = new int [newLength]; 
 System.arraycopy（original，from，copy，0，
 Math.min（original.length  -  from，newLength））; 
返回副本; 
} 
  

此代码认为到导致int溢出（由于从为 Integer.MIN_VALUE ），导致消极的 newLength 。

I was working on arrays today and suddenly I came across a scenario throwing unexpected exceptions.

If you look at the code below , I think it must throw ArrayIndexOutOfBoundsException, but surprisingly it is throwing IllegalArgumentException instead:

import java.util.Arrays;
public class RangeTest {
public static void main(String[] args) {
    int[] a = new int[] {0,1,2,3,4,5,6,7,8,9};
    int[] b = Arrays.copyOfRange(a, Integer.MIN_VALUE, 10);
    // If we'll use Integer.MIN_VALUE+100 instead Integer.MIN_VALUE,
    // OutOfMemoryError will be thrown
    for (int k = 0; k < b.length; k++)
        System.out.print(b[k] + " ");
   }
}

Can anybody help me and let me know if I am mistaken?

解决方案

Well, the Javadoc says :

Looking at the implementation, you can see that you got an IllegalArgumentException exception instead of ArrayIndexOutOfBoundsException due to int overflow :

public static int[] copyOfRange(int[] original, int from, int to) {
    int newLength = to - from;
    if (newLength < 0)
        throw new IllegalArgumentException(from + " > " + to);
    int[] copy = new int[newLength];
    System.arraycopy(original, from, copy, 0,
                     Math.min(original.length - from, newLength));
    return copy;
}

This code thinks that from > to because to-from caused int overflow (due to from being Integer.MIN_VALUE), which resulted in a negative newLength.

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