字符之间的正则表达式空格（Java 开头除外）

Question

I've been struggling my mind for the past couple of hours in order to get the following behaviour in a sentence of characters:

John is $@^&%$#@&$^12(random chars...) - match
John is $@^&%$#@&$^12(random chars...) - match (some spaces at the end)
John is $@^&%$#@&$^12(random chars...) - unmatch (some spaces at the beginning)

I could not find any answer to get the right regex to be used in Java for a filter in edit text. Must specify that I am not allowed to change project setting therefore some errors pop-up such as:

'\s' and '\' escape sequences are not supported at language level '8'
Illegal escape character in string literal

Here are a few variants that I tried:

"^[^ ]+.+"
"^[a-zA-Z!@#$%^&*()_+-={};',.<>?/:][ ]*.*"
"^[a-zA-Z0-9_ ]*$"
"^[^ ]+( .+)*$"
"^\\w+( \\w+)*$"
"^- (\\w+( \\w+)*)$"
"^[a-zA-Z0-9_][a-zA-Z0-9_ ]*[a-zA-Z0-9_]$"
"^[^ ]+[\\s]*"
"^[^-\\s][\w\s-]+$"

None of them works

EDIT

Here is all the code:

        final EditText nameInput = line2.findViewById(R.id.input_value);
        nameInput.setFilters(new InputFilter[] {new NoSpaceStartInputFilter()});

private static class NoSpaceStartInputFilter implements InputFilter {
        
        private Pattern mPattern;
        
        public NoSpaceStartInputFilter() {
            mPattern = Pattern.compile("^[^ ]+.+");
            mPattern = Pattern.compile("^[a-zA-Z!@#$%^&*()_+-={};',.<>?/:][ ]*.*");
            mPattern = Pattern.compile("^[a-zA-Z0-9_ ]*$");
            mPattern = Pattern.compile("^[^ ]+( .+)*$");
            mPattern = Pattern.compile("^\\w+( \\w+)*$");
            mPattern = Pattern.compile("^- (\\w+( \\w+)*)$");
            mPattern = Pattern.compile("^[a-zA-Z0-9_][a-zA-Z0-9_ ]*[a-zA-Z0-9_]$");
            mPattern = Pattern.compile("^[^ ]+[\\s]*");
            mPattern = Pattern.compile("^[^-\\s][\w\s-]+$");
            mPattern = Pattern.compile("^(?!\\s+\\S)\\S*\\s.*");
        }

        @Override
        public CharSequence filter(CharSequence charSequence, int i, int i1, Spanned spanned, int i2, int i3) {
            Matcher matcher = mPattern.matcher(charSequence);
            if (!matcher.matches())
                return "";
            return null;
        }
    }

Answer 1

You can use

text.matches("\\S.*")

The String#matches requires a full string match and the pattern matches a string that matches

• \S - a non-whitespace as the first char and then
• .* - any zero or more chars other than line break chars as many as possible.

To allow line break chars, use

text.matches("(?s)\\S.*")
text.matches("\\S[\\w\\W]*")