如何在Java中计算@，＃，+等符号的数量

Question

I'm trying to write a code to count number of letters,characters,space and symbols in a String . But I don't know how to count Symbols.

Is there any such function available in java?

Answer 1

That very much depends on your definition of the term symbol .

A straight forward solution could be something like

Set<Character> SYMBOLS = Set.of('@', ' ', ....
for (int i=0; i < someString.length(); i++} {
  if (SYMBOLS.contains(someString.charAt(i)) { 

That iterates the chars someString , and checks each char whether it can be found within that predefined SYMBOLS set.

Alternatively, you could use a regular expression to define "symbols", or, you can rely on a variety of existing definitions. When you check the regex Pattern language for java, you can find

\w  A word character: [a-zA-Z_0-9]
\W  A non-word character: [^\w]

for example. And various other shortcuts that denote this or that set of characters already.

Answer 2

Please post what you have tried so far

If you need the count of individual characters - you better iterate the string and use a map to track the character with its count

Or

You can use a regex if just the overall count would enough like below

while (matcher.find() ) {count++} 

Answer 3

One way of doing it would be to just iterate over the String and compare each character to their ASCII value

String str = "abcd!@#";
        for(int i=0;i<str.length();i++)
        {
            if(33==str.charAt(i))
                System.out.println("Found !");
        }

lookup here for ASCII values https://www.cs.cmu.edu/~pattis/15-1XX/common/handouts/ascii.html