Wrapper classes for ICSE Class 10, with every method run in Java.

char dg = '8';
System.out.println(dg - '0' + 1);
System.out.println(Integer.parseInt("" + dg) + 1);

// Output
9
9

parseInt needs a String, so "" + dg turns the char into one first. Subtracting '0' gives the same value with char arithmetic.

import java.util.Scanner;
class CharCensus {
    String text;   // the sentence entered
    int upper;     // uppercase letters
    int lower;     // lowercase letters
    int digits;    // digit characters
    int spaces;    // whitespace characters
    int others;    // everything else

    CharCensus() {                 // default constructor
        text = "";
        upper = 0;
        lower = 0;
        digits = 0;
        spaces = 0;
        others = 0;
    }

    void accept() {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter a sentence:");
        text = sc.nextLine();
    }

    void count() {
        for (int i = 0; i < text.length(); i++) {
            char ch = text.charAt(i);
            if (Character.isUpperCase(ch))
                upper++;
            else if (Character.isLowerCase(ch))
                lower++;
            else if (Character.isDigit(ch))
                digits++;
            else if (Character.isWhitespace(ch))
                spaces++;
            else
                others++;
        }
    }

    void display() {
        System.out.println("Uppercase letters : " + upper);
        System.out.println("Lowercase letters : " + lower);
        System.out.println("Digits            : " + digits);
        System.out.println("Spaces            : " + spaces);
        System.out.println("Other characters  : " + others);
    }

    public static void main(String args[]) {
        CharCensus ob = new CharCensus();
        ob.accept();
        ob.count();
        ob.display();
    }
}

One if-else-if chain means each character is counted exactly once. The final else catches commas, colons and every other symbol.

import java.util.Scanner;
class MarksLine {
    String line;    // the record, for example Riya,78,91,66
    String name;    // the part before the first comma
    int total;      // sum of the marks
    int count;      // number of marks found
    int high;       // highest mark

    MarksLine(String l) {          // parameterized constructor
        line = l.trim() + ",";      // a comma at the end closes the last part
        name = "";
        total = 0;
        count = 0;
        high = 0;
    }

    void extract() {
        String part = "";
        for (int i = 0; i < line.length(); i++) {
            char ch = line.charAt(i);
            if (ch != ',') {
                part = part + ch;
            } else {
                if (name.equals(""))
                    name = part;                       // first part is the name
                else {
                    int m = Integer.parseInt(part.trim()); // text to int
                    total = total + m;
                    count++;
                    if (m > high)
                        high = m;
                }
                part = "";
            }
        }
    }

    void display() {
        double avg = (double) total / count;
        System.out.println("Name    : " + name);
        System.out.println("Marks   : " + count);
        System.out.println("Total   : " + total);
        System.out.println("Highest : " + high);
        System.out.println("Average : " + Math.round(avg * 10) / 10.0);
    }

    public static void main(String args[]) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter name and marks separated by commas:");
        String s = sc.nextLine();
        MarksLine ob = new MarksLine(s);
        ob.extract();
        ob.display();
    }
}

part.trim() before parseInt is what lets the record contain a space after a comma; without it the program stops with a NumberFormatException.