如何计算给定参数中的空格？

Question

I find it strange why spaceCount doesn't add up when the expression is "12 + 1". I get an output 0 for spaceCount even though it should be 2. Any insight would be appreciated!

public int countSpaces(String expr) {
    String tok = expr;

    int spaceCount = 0;

    String delimiters = "+-*/#! ";
    StringTokenizer st = new StringTokenizer(expr, delimiters, true);

    while (st.hasMoreTokens()) {
        if ((tok = st.nextToken()).equals(" ")) {
            spaceCount++;
        }
    }
    return spaceCount; // the expression is: 12 + 1, so this should return 2, but it returns 0;
}

Answer 1

您的代码似乎没问题，但如果您想要计算空格，可以使用此代码：

int count = str.length() - str.replace(" ", "").length();

Answer 2

A tokenizer is overkill (and doesn't really help you) for this problem. Just loop through all the characters and count the spaces:

public int countSpaces( String expr )
{
    int count = 0;
    for( int i = 0; i < expr.length(); ++i )
    {
        if( expr.charAt(i) == ' ' )
            ++count;
    }
    return count;
}

Answer 3

另一个单行解决方案可能是以下，它也对字符串执行NULL检查。

int spacesCount = str == null ? 0 : str.length() - str.replace(" ", "").length();

Answer 4

Can also use:

String[] strArr = st.split(" ");

if (strArr.length > 1){
   int countSpaces = strArr.length - 1;
}

Answer 5

This will find white spaces, including special ones. You can keep the pattern so you don't need to compile it every time. If just need to search for " ", a loop should do it instead.

Matcher spaces = Pattern.compile("\\\\s").matcher(argumentString); int count = 0; while (spaces.find()) { count++; }