我已经编写了一个代码来从ip地址输入中查找子网掩码、广播id等。然而,我得到了以下错误,并且代码只是部分运行,没有语法错误:
linux@ubuntu:~/Desktop$ javac Subnet.java
linux@ubuntu:~/Desktop$ java Subnet
Enter the ip address:138.101.114.250
IP in Binary is10001010011001010111001011111010
Enter the number of addresses:26
Number of bits reqd for address=5
the subnet mask is=27
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3
at Subnet.main(Subnet.java:31)
linux@ubuntu:~/Desktop$ ^C
这是代码
import java.util.Scanner;
class Subnet{
public static void main(String args[])
{
Scanner sc=new Scanner(System.in);
System.out.print("Enter the ip address:");
String ip=sc.nextLine();
String split_ip[]=ip.split("\\.");
String split_bip[]=new String[4];
String bip="";
for(int i=0;i<4;i++)
{
split_bip[i]=appendZeros(Integer.toBinaryString(Integer.parseInt(split_ip[i])));
bip+=split_bip[i];
}
System.out.println("IP in Binary is"+bip);
System.out.print("Enter the number of addresses:");
int n = sc.nextInt();
int bits=(int)Math.ceil(Math.log(n)/Math.log(2));
System.out.println("Number of bits reqd for address="+bits);
int mask=32-bits;
System.out.println("the subnet mask is="+mask);
int fbip[]=new int[32];
for (int i=0;i<32;i++)fbip[i]=(int)bip.charAt(i)-48;
for(int i=31;i>31-bits;i--)
fbip[i]&=0;
String fip[]={"","",""};
for(int i=0;i<32;i++)
fip[i/8]=new String(fip[i/8]+fbip[i]);
System.out.print("Subnet address is=");
for(int i=0;i<4;i++){
System.out.print(Integer.parseInt(fip[i],2));
if(i!=3)System.out.print(".");
}
System.out.println();
int lbip[]=new int[32];
for(int i=0;i<32;i++)lbip[i]=(int)bip.charAt(i)-48;
for(int i=31;i>31-bits;i--)
lbip[i]|=1;
String lip[]={"","",""};
for(int i=0;i<32;i++)
lip[i/8]=new String(lip[i/8]+lbip[i]);
System.out.print("Broadcast address is=");
for(int i=0;i<4;i++){
System.out.print(Integer.parseInt(lip[i],2));
if(i!=3)System.out.print(".");
}
System.out.println();
}
static String appendZeros(String s)
{
String temp=new String("00000000");
return temp.substring(s.length())+s;
}
}
这只是一个非常小的错误,但我不知道在哪里。
发布于 2018-10-26 18:00:47
ArrayIndexOutOfBoundsException
意味着您正在尝试访问一个不存在于数组中的元素,即一个索引大于最后一个元素的索引的元素。
String[] someArray = new String[]{"a - index 0", "b - index 1", "c - index 2"}; String inexistent = someArray[3]; //This will throw an ArrayIndexOutOfBoundsException since there are only three elements in the array, the last having index 2 (it always starts at 0 = zero-based)
您的错误是Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 3 at Subnet.main(Subnet.java:31)
,您应该查看Subnet.java
文件的第31行,看看您是如何计算数组索引的
在该行添加断点并检查数组和计算出的索引肯定会有所帮助
发布于 2018-10-26 20:11:21
我终于发现了一个小错误:
String fip[]={"","",""};
它位于完整代码的中间。问题是我提交了4个字符串,但在上面的错误代码行中,我只使用了3个,答案是我应该再添加一个括号,所以总共4个,如下所示:
String fip[]={"","","",""};
https://stackoverflow.com/questions/53005370
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