Java字符串中的特殊字符

Question

I am trying to write a code to find the special characters in a java string.

Special characters are a-zA-Z.?@;'#~!£$%^&*()_+-=¬`,./<>

Please help me to understand and write how can I implement this.

Thank you

Answer 1

You can create a char array from a String.

String string = "test";
char[] charArray = string.toCharArray();

Then you can loop through all the characters:

for(char character: charArray){
    //check if the character is special and do something with it, like adding it to an List.
}

Answer 2

You can use a Scanner to find the invalid characters in your String:

/* Regex with all character considered non-special */
public static final String REGULAR_CHARACTERS = "0-9a-z";

public static String specialCharacters(String string) {
    Scanner scanner = new Scanner(string);
    String specialCharacters= scanner.findInLine("[^" + REGULAR_CHARACTERS  + "]+");
    scanner.close();
    return specialCharacters;
}

The findInLine returns a String with all characters not included in the constant (all special characters). You need to setup the constant with all the characters that you consider non-special.

Alternatively, if you want to setup only the characters you want to find, you can modify the example above with:

public static final String SPECIAL_CHARACTERS = "a-zA-Z.?@;'#~!£$%^&*()_+-=¬`,./<>";
....
String specialCharacters= scanner.findInLine("[" + SPECIAL_CHARACTERS + "]+");
....

The characters used in the constants need to be scaped as usual for regular expressions.

For example, to add the ] character, you need to use \\\\]