Reading characters and checking if they're a number

问题

I am trying to get a method that checks if character after the symbol & is a number or a letter; if a number, it is translated into binary; and if it is a letter, it is set to 16 and is incremented by 1 if a different word is being used. The trouble is, this doesn't work for me, for some reason. Any suggestions?

try {
       ReadFile files = new ReadFile(file.getPath());
       String[] anyLines = files.OpenFile();

       int i;

       for (i=0; i<anyLines.length; i++) {
           String input = anyLines[i];
           String[] lines = input.split("\n");

           int wordValue = 16;

           Map<String, Integer> wordValueMap = new HashMap<String, Integer>();

           for (String line : lines) {
               // if line doesn't begin with &, then ignore it
               if (!line.startsWith("&")) {
                   continue;
               }

               // remove &
               line = line.substring(1);

               Integer binaryValue = null;

               if (line.matches("\\d+")) {
                   binaryValue = Integer.toBinaryString(131072 +
                              Integer.parseInt(anyLines[i])).substring(2,18);
               }
               else if (line.matches("\\w+")) {
                   binaryValue = wordValueMap.get(line);

                   if (binaryValue == null) {
                       binaryValue = wordValue;
                       wordValueMap.put(line, binaryValue);
                       wordValue++;
                   }
               }
           }
       }

INPUT:

&4
...
&hello
...
&ok

OUTPUT:

(5 translated into binary) : 0000000000000100
...
(16 translated into binary)
...
(17 translated into binary, or 16+1)

Here's the output of your method:

101
1001100
1001100
1001100
1001100
1001100
1001100
1001100
&5
1110110000010000 
&hello
1110001100001000 
&goodbye
1110101010001000 
(NEXT)
&goodbye
1111000010001000 
&hello
1110001110001000 
&BILL
1110001100000110 
&NEXT
1110101010000111 
(BILL)
&BILL
1110101010000111

And here's the original text that i'm reading and looping through (anyLines[i] without any modifications):

&5
var1 
&hello
var2 
&goodbye
var2 
(NEXT)
&goodbye
var3 
&hello
var4 
&BILL
var5 
&NEXT
var6 
(BILL)
&BILL
var5

var is just a variable that has a value. I already took care of those.

Here's my attempt:

String input = "This is a test line\n"
           + "&hello\n"
           + "&4\n"
           + "&32";

String[] lines = input.split("\n");
int wordValue = 26;

Map<String, Integer> wordValueMap = new HashMap<String, Integer>();

for (String currentLine : lines)
{
if (!currentLine.startsWith("&"))
{
    continue;
}

currentLine = currentLine.substring(1);
Integer value;

if (currentLine.matches("\\d+"))
{
    value = Integer.parseInt(currentLine);
}
else if (currentLine.matches("\\w+"))
{
    value = wordValueMap.get(currentLine);

    if(value == null)
    {
        int binaryValue = wordValue++;
        wordValueMap.replace(currentLine, binaryValue);
        /*
         * This is just there to ensure that the print statement below doesn't have a 
         * null value.
         */
        value = binaryValue;
    }
}
else
{
    System.out.println("Invalid input");
    break;
}

System.out.println(Integer.toBinaryString(value));
}

回答1:

There are numerous problems with your code. To begin with, you'll have to parse the value you get after the toBinaryString() call.

binaryValue = Integer.parseInt(Integer.toBinaryString(131072 +
                          Integer.parseInt(anyLines[i])).substring(2,18));

The usage of anyLines[i] as an argument to the parseInt() function in that code is also incorrect. From what I see of your code, anyLines[i] is a string with newLines and other things in it, which obviously cannot be parsed into an integer.

The code below seems to work. I've changed the storage of the HashMap so that it stores regular integers, instead of attempting to store a binary representation as an integer value.

String input = "This is a test line\n"
               + "&hello\n"
               + "&4\n"
               + "&32";

String[] lines = input.split("\n");
int wordValue = 26;

Map<String, Integer> wordValueMap = new HashMap<String, Integer>();

for (String currentLine : lines)
{
    if (!currentLine.startsWith("&"))
    {
        continue;
    }

    currentLine = currentLine.substring(1);
    Integer value;

    if (currentLine.matches("\\d+"))
    {
        value = Integer.parseInt(currentLine);
    }
    else if (currentLine.matches("\\w+"))
    {
        value = wordValueMap.get(currentLine);

        if(value == null)
        {
            int binaryValue = wordValue++;
            wordValueMap.put(currentLine, binaryValue);
            /*
             * This is just there to ensure that the print statement below doesn't have a 
             * null value.
             */
            value = binaryValue;
        }
    }
    else
    {
        System.out.println("Invalid input");
        break;
    }

    System.out.println(Integer.toBinaryString(value));
}

As a side note, I hope you know that this will fail in the event of a number followed by a words, like sentences. But if your input will never have any of that, it's a non-issue.

来源：https://stackoverflow.com/questions/6133106/reading-characters-and-checking-if-theyre-a-number

标签

java

file

integer

character

letter