public class StringsDemo1 
{
	public static void main(String[] args)
	{
		String firstName = new String("John");	// Strings are rarely instantiated this way
		String lastName = "Doe";                // since Java allows you to shorten it to this way
		String middleName;                      // middleName is null since it was not initialized
		
		System.out.println("The length of " + firstName + " is " + firstName.length());
		// System.out.println("The length of " + middleName + " is " + middleName.length());	// error since middleName is null
		
		middleName = "";
		System.out.println("The length of " + middleName + " is " + middleName.length());	// okay since middleName is the null string
		
		// null is different from a null string similar to how zero is different from the empty set in math
		
		int zip = 19610;
		zip = zip + 1;
		System.out.println("zip is " + zip);             // zip is 19611
		
		String zipCode = zip + "";                       // you can turn an int into a String by concatenating the null string to it
		System.out.println("zipCode is " + zipCode);     // zipCode is 19611
		
		zipCode = zipCode + -1234;                       // concatenation occurs here since at least one of the two arguments, zipCode, is a String
		System.out.println("zipCode is now " + zipCode); // zipCode is now 19611-1234
		
		String wholeName = firstName;
		wholeName += " ";                                // concatenation
		wholeName += lastName;
		System.out.println("wholeName is " + wholeName); // wholeName is John Doe
		
		System.out.println("first name is " + wholeName.substring(0, 4));                  // firstName is John
		System.out.println("last name is " + wholeName.substring(5, 8));                   // lastName is Doe
		System.out.println("last name is " + wholeName.substring(5, wholeName.length()));  // lastName is Doe
		System.out.println("last name is " + wholeName.substring(5));                      // lastName is Doe
		System.out.println("The last letter of " + wholeName + " is " + wholeName.substring(wholeName.length() - 1)); // e
		System.out.println("The letter in the 3rd position of " + wholeName + " is " + wholeName.charAt(3));          // n
		System.out.println("The letter o is first found in position " + wholeName.indexOf("o") + " of " + wholeName); // 1
		System.out.println("The letter z is first found in position " + wholeName.indexOf("z") + " of " + wholeName); // -1
	
		int posBlankSpace = -1;	            // position of blank space
		posBlankSpace = wholeName.indexOf(" ");
		System.out.println("The first name is " + wholeName.substring(0, posBlankSpace)); // The first name is John
		System.out.println("The last name is " + wholeName.substring(posBlankSpace + 1)); // The last name is Doe
		
		String name1 = "Jane";
		String name2 = name1;
		name1 = "Joan";
		System.out.println("name1 is " + name1 + " and name2 is " + name2);                // name1 is Joan and name2 is Jane
		// no aliasing occurs because Strings are immutable and are not aliased like other objects
	}
}