Chapter 3- String Methods in Java

String Methods operate on Java Strings. They can be used to find the length of the string, convert to lowercase, etc.

Some of the commonly used String methods are:

String name = “Aryadeep”;

(Indexes of the above string are as follows: 0-A, 1-r, 2-y, 3-a, 4-d, 5-e, 6-e, 7-p )

1. length() – Returns the length of String name. (8 in this case)

2. toLowerCase() – Returns a new String which has all the lowercase characters from the String name.

3. toUpperCase() – Returns a new String which has all the uppercase characters from the String name.

4. trim() – Returns a new String after removing all the leading and trailing spaces from the original string.

5. substring(int start) – Returns a substring from start to the end. Substring(3) returns “adeep”. [Note that index starts from 0]

6. substring(int start, int end) – Returns a substring from the start index to the end index. The start index is included and the end is excluded.

7. replace(‘r’, ‘p’) – Returns a new string after replacing r with p. Apyadeep is returned in this case. (This method takes char as argument)

8. startsWith(“Ar”) – Returns true if name starts with string “Ar”. (True in this case)

9. endsWith(“ep”) – Returns true if name ends with string “ry”. (True in this case)

10. charAt(2) – Returns the character at a given index position. (y in this case)

11. indexOf(“s”) – Returns the index of the given string.

For e.g. name.indexOf(“r”) returns 1 which is the first occurrence of r in string “Aryadeep”, -1 otherwise.

12. indexOf(“s”, 3) – Returns the index of the given String starting from index 3(int). (-1 is returned in this case)

13. lastIndexOf(“e”) – Returns the last index of the given string. (3 in this case)

14. lastIndexOf(“n”,4) – Returns the last index of the given string before index 6.

15. equals(“Harry”) – Returns true if the given string is equal to “Harry” false otherwise [Case sensitive]

16. equalsIgnoreCase(“harry”) – Returns true if two strings are equal ignoring the case of characters.

Escape Sequence Characters

The sequence of characters after backslash ‘\’ = Escape Sequence Characters

Escape Sequence Characters consist of more than one character but represent one character when used within the strings.

Examples: \n (newline), \t (tab), \’ (single quote), \\ (backslash), etc.

Code as described in the video

package com.company;

public class cwh_14_string_methods {
    public static void main(String[] args) {
        String name = "Harry";
        // System.out.println(name);
        int value = name.length();
        //System.out.println(value);

        //String lstring = name.toLowerCase();
        //System.out.println(lstring);

        //String ustring = name.toUpperCase();
        //System.out.println(ustring);

        //String nonTrimmedString = "     Harry     ";
        //System.out.println(nonTrimmedString);

        //String trimmedString = nonTrimmedString.trim();
        //System.out.println(trimmedString);

        //System.out.println(name.substring(1));
        //System.out.println(name.substring(1,5));

        //System.out.println(name.replace('r', 'p'));
        //System.out.println(name.replace("r", "ier"));

        //System.out.println(name.startsWith("Har"));
        //System.out.println(name.endsWith("dd"));

        //System.out.println(name.charAt(4));

        //String modifiedName = "Harryrryrry";
        //System.out.println(modifiedName.indexOf("rry"));
        //System.out.println(modifiedName.indexOf("rry", 4));
        //System.out.println(modifiedName.lastIndexOf("rry", 7));

        //System.out.println(name.equals("Harry"));
        System.out.println(name.equalsIgnoreCase("HarRY"));

        System.out.println("I am escape sequence\tdouble quote");




    }
}