public static String[] removeCharacters(String[] arr){


    String[] str = new String[arr.length];

    for (int i = 0; i <arr.length; i  ) {
        if(Character.isLetter(arr[i].charAt(i)))
            str[i]  = arr[i].charAt(i);
        else
            str[i] = "";
    }
    return str;
}

I'm trying to write a method that returns to String array and takes an String array argument. I need remove special characters from the element and return the element without specials.

• For example; ["Hel123&$$o", "#$%World", "###"] will return to
• ["Hello", "World", "",] as a output.
• I also converted back to String, remove those special characters and split back again to an Array but when i convert to String it all comes together and there is no split point and I don't want to do it with Regex so i'm trying to do without it. With my solution I'm getting null so i couldn't fix.

CodePudding user response：

Here's a changed version. You have to use a nested for loop - the first iterates over the input String[] and the nested one over the char[] in each string.

I have also used some variables in place of repeated array references for easy reading.

public class StrArray{
    public static void main( String[] args ){
        String[] input = new String[]{ "Hel123&$$o", "#$%World", "###" };
        String[] strArr = removeCharacters( input );
        Arrays.stream( strArr ).forEach( s -> System.out.println( "'"   s   "'" ) );
    }

    public static String[] removeCharacters( String[] arr ){
        String[] str = new String[ arr.length ];

        for( int i = 0; i < arr.length; i   ){
            String input = arr[ i ];
            
            /* If the input string in empty, skip.*/
            int k = 0;
            if( input == null || input.length() == 0 )
                str[ i ] = "";
            else{
                /* Construct a char[] containing all the relevant chars. */
                char[] chars = new char[ input.length() ];
                for( int j = 0; j < input.length(); j   ){
                    char c = input.charAt( j );
                    if( Character.isLetter( c ) ) chars[ k   ] = c;
                }

                /* Now, convert the char[] into a string. */
                str[ i ] = String.valueOf( chars, 0, k );
            }
        }

        return str;
    }
}

I have quoted each string while printing. Hence, running this gives the following output.

'Helo'
'World'
''

CodePudding user response：

The problem is that you are iterating over the array of strings but not over the array of characters of each string. You can use a loop to iterate over the array of Strings and a nested loop to iterate over the characters of each String.

Here I'm using StringBuilder to concatenate the Strings since it is more efficient than using . This is because the String object is immutable, so each call for concatenation will create a new String object. On the other hand, StringBuilder is a mutable array of characters.

import java.util.Arrays;

public class MyClass {
    public static void main(String args[]) {

        String[] stringArray = 
        new String[]{ "Hell123&$$o", "#$%World", "###" };
        System.out.println(
        Arrays.toString(removeCharacters(stringArray)));
    }

    public static String[] removeCharacters(String[] arr) {
        String[] str = new String[arr.length];

        for (int i = 0; i < arr.length; i  ) {
            StringBuilder strBuilder = new StringBuilder();
            for (int j = 0; j < arr[i].length(); j  ) {
                if (Character.isLetter(arr[i].charAt(j)))
                    strBuilder.append(arr[i].charAt(j));
            }
            str[i] = strBuilder.toString();
        }
        return str;
    }
}