I'm trying to learn java by myself and I came across the two programs attached below, but I can't figure out how to do them.
4a. Write a program in which the main method calls a method with the heading public static char changeCase(char ch) that if ch is a lowercase letter, the method will return the corresponding uppercase letter, and if ch is a uppercase letter, the method will return the corresponding lowercase letter. If ch is not a letter, the method returns the same value of ch. Thus, for instance, changeCase('a') returns A, changeCase('B') returns b, and changeCase('3') returns 3. Note that the uppercase letters have a unicode (ascii code) value that is 32 lower than the corresponding lowercase ones.
Your main method should contain three calls to changeCase() for each case mentioned above.
4b. Write a method public static char toUpperCase(char ch) that if ch is a lowercase letter, the method will return the corresponding uppercase letter, and if ch is any other character, it will return that character. Read a string consisting of "My country tis of thee, Sweet land of liberty, Of thee I sing" and using toUpperCase() in a loop, convert the entire string to uppercase letters, where the string is assigned to the variable s.