为什么我的索引越界异常? [英] Why am I getting index out of bounds exception?

问题描述

我已经制作了这段代码来将整个以 10 为基数的数字转换为二进制.我相信代码是它需要的一切，但我无法让 ArrayList 工作.

我在这个网站上花了几个小时，其他人尝试了无数次更改，但无济于事.

我已经编译了没有错误的代码，但是一旦我运行它并输入int，程序就会崩溃.

代码如下:

import java.util.Scanner;导入 java.util.ArrayList;公共类 BinaryConverter {公共静态无效主(字符串 [] args){扫描仪输入 = new Scanner(System.in);ArrayList<整数>binary = new ArrayList();int a = in.nextInt();二进制 = binaryConverter(a);for (int i = binary.size(); i > -1; i = i - 1){System.out.print(binary.get(i));}}公共静态 ArrayListbinaryConverter(整数n){ArrayList<整数>余数 = 新的 ArrayList();而 (n/2 != 0) {余数.add(n%2);n = n/2；}余数.add(n%2);返回余数；}}

这些是当我输入一个数字时 java 向我抛出的异常.

Jons-iMac:java jon$ java BinaryConverter142线程main"中的异常java.lang.IndexOutOfBoundsException:长度为 8 的索引 8 越界在 java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)在 java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)在 java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:248)在 java.base/java.util.Objects.checkIndex(Objects.java:372)在 java.base/java.util.ArrayList.get(ArrayList.java:440)在 BinaryConverter.main(BinaryConverter.java:16)

我希望这是足够的信息.

解决方案

在你的代码中，你get通过被错误评估的索引值.

<块引用>

 for (int i = binary.size(); i > -1; i = i - 1){System.out.print(binary.get(i));}

binary.size() 的赋值确实越界了，因为索引从 binary.size() 开始计数到零，但是超出了被绑定的范围从零到 binary.size()-1.

I've made this code to convert whole base 10 numbers into binary. The code I believe is everything that it needs to be but I can't get ArrayList to work.

I've spent a few hours on this site and other trying countless changes to no avail.

I've gotten the code to compile without errors but as soon as I run it and enter an int the program crashes.

Here is the code:

import java.util.Scanner;
import java.util.ArrayList;

public class BinaryConverter {
   public static void main(String[] args) {
      Scanner in = new Scanner(System.in);
      ArrayList<Integer> binary = new ArrayList<Integer>();
      int a = in.nextInt();
      binary = binaryConverter(a);
      for (int i = binary.size(); i > -1; i = i - 1){
         System.out.print(binary.get(i));
      }
  }
  public static ArrayList<Integer> binaryConverter(Integer n) {
   ArrayList<Integer> remainder = new ArrayList<Integer>();
   while (n/2 != 0) {
      remainder.add(n%2);
      n = n/2;
   }
   remainder.add(n%2);
   return remainder;
  }
}

These are the exceptions java throws at me when I input a number.

Jons-iMac:java jon$ java BinaryConverter
142

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 8 out-of-bounds for length 8
    at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
    at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
    at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:248)
    at java.base/java.util.Objects.checkIndex(Objects.java:372)
    at java.base/java.util.ArrayList.get(ArrayList.java:440)
    at BinaryConverter.main(BinaryConverter.java:16)

I hope this is enough information.

解决方案

In your code you get the value by index which is evaluated incorrectly.

  for (int i = binary.size(); i > -1; i = i - 1){
     System.out.print(binary.get(i));
  }

Assignment of binary.size() indeed out of bounds, because indexes counted from binary.size() to zero, but it is out of range which is bound from zero to binary.size()-1.

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