我必须过滤Ipv4（32位）的IP地址，但是当我使用最多32位{array [32 bit]}的数组索引时，它会给出错误。所以我将ip分为三部分; 1-one部分包含25位{array [25 bit]}的索引值 2-秒部分包含5比特的值，并且该值使用5到32解码器解码。 3-两位的第三部分表示4个不同的阵列，其中5位解码值存储在25位地址位置。 它给出了第四个短阵列的错误。 当我将地址减少到24位并解码5位存储在8个不同的短阵列中时，这里3位选择8个阵列中的数据，那么它也会在第8个短阵列上产生错误， “线程中的异常”主“java.lang.OutOfMemoryError：Java堆空间”
如何解决此问题？ 是否有其他数据结构，如linkedlist，tree等可以解决这个问题？
import java.util.Scanner; class IPAddress3 {
public static void main(String[] args) {
Scanner input=new Scanner(System.in);
System.out.println("Enter IP address to search from list:");
String ipAddress=input.nextLine();
//String ipAddress="171.255.100.23";
String[] octets = ipAddress.split("\\.");
StringBuilder sb = new StringBuilder();
for (String octet : octets) {
int number = Integer.parseInt(octet);
if(number>255)
{
System.out.println("Error:Invalid Ip address,\n" +
"Each octet should be less or equal to 255\n");
System.exit(0);
}
else{
String binaryPart = Integer.toBinaryString(number);
if (binaryPart.length() < 8) {
for (int i = binaryPart.length(); i < 8; i++) {
binaryPart = "0" + binaryPart;
}
}
sb.append(binaryPart);
}
}
String binaryForm = sb.toString();
System.out.println(binaryForm);
System.out.println("2 MSB: " + binaryForm.substring(0, 2));
System.out.println("5 bits: " + binaryForm.substring(2, 7));
System.out.println("25 LSB: " + binaryForm.substring(7));
String MSB2Bit=binaryForm.substring(0, 2);
String fivebits= binaryForm.substring(2, 7);
String twenty5bits=binaryForm.substring(8);
byte msb2Bit=Byte.parseByte(MSB2Bit);
byte data=Byte.parseByte(fivebits,2);
int address=Integer.parseInt(twenty5bits,2);
System.out.println("Data:\t"+data);
System.out.println("Address: "+address);
short[] Array0=new short[33554432];
short[] Array1=new short[33554432];
short[] Array2=new short[33554432];
short[] Array3=new short[33554432];//error in this line
/*
short[] Array0=new short[16777216];
short[] Array1=new short[16777216];
short[] Array2=new short[16777216];
short[] Array3=new short[16777216];
short[] Array4=new short[16777216];
short[] Array5=new short[16777216];
short[] Array6=new short[16777216];
short[] Array7=new short[16777210];// error here
/*
Array0[1677721]=127;
Array1[1677721]=127;
Array2[1677721]=127;
int thirty2BitWord = 0 ;// Array0[ad]=Array0[ad] | Arra0[ad];
int filterWord = 8;
switch(data)
{
case 0:
thirty2BitWord=1;
break;
case 1:
thirty2BitWord=2;
break;
case 2:
thirty2BitWord=4;
break;
case 3:
thirty2BitWord=8;
break;
case 4:
thirty2BitWord=16;
break;
case 5:
thirty2BitWord=32;
break;
case 6:
thirty2BitWord=64;
break;
case 7:
thirty2BitWord=128;
break;
case 8:
thirty2BitWord=256;
break;
case 9:
thirty2BitWord=512;
break;
case 10:
thirty2BitWord=1024;
break;
case 11:
thirty2BitWord=2048;
break;
case 12:
thirty2BitWord=4096;
break;
case 13:
thirty2BitWord=8192;
break;
case 14:
thirty2BitWord=16384;
break;
case 15:
thirty2BitWord=32768;
break;
case 16:
thirty2BitWord=65536;
break;
case 17:
thirty2BitWord=131072;
break;
case 18:
thirty2BitWord=262144;
break;
case 19:
thirty2BitWord=524288;
break;
case 20:
thirty2BitWord=1048576;
break;
case 21:
thirty2BitWord=2097152;
break;
case 22:
thirty2BitWord=4194304;
break;
case 23:
thirty2BitWord=8388608;
break;
case 24:
thirty2BitWord=16777216;
break;
case 25:
thirty2BitWord=33554432;
break;
case 26:
thirty2BitWord=67108864;
break;
case 27:
thirty2BitWord=134217728;
break;
case 28:
thirty2BitWord=268435456;
break;
case 29:
thirty2BitWord=536870912;
break;
case 30:
thirty2BitWord=1073741824;
break;
case 31:
thirty2BitWord=2147483647;
break;
}
if(msb2Bit==0)
{
filterWord=thirty2BitWord & Array0[address];
}
else if(msb2Bit==1)
{
filterWord=thirty2BitWord & Array1[address];
}
else if(msb2Bit==2)
{
filterWord=thirty2BitWord & Array2[address];
}
/* else
{
filterWord=thirty2BitWord & Array3[address];
}*/
byte filterbit;
if(filterWord==0)
{
filterbit=0;
System.out.println("No such address is found in blacklist, So Allow\n");
}
else
{
filterbit=1;
System.out.println("IP match, So block this address\n");
}
}
}
答案 0 :(得分：-1)
对于短期运行，您可以通过增加内存来修复堆大小错误：
How to increase application heap size in Eclipse?
我没有检查过你的代码太多，因为这个错误就是虚拟机内存不足。可能有一种更好的方法可以做到这一点，但如果程序只需要更多的RAM，这应该可以解决问题！