package examples;
/**
 * CS401 Example 3
 * This handout demonstrates some issues relating to reference variables and
 * using them correctly.
 * 
 * @author Dr. Ramirez, PJ Dillon
 */
public class ex3
{
	public static void main(String[] args)
	{
		// The StringBuffer class is related to the String class.  See
		// Section 3.2 in the text for details on the String class.  
		// StringBuffer objects can also store and access strings of
		// text.  However, unlike String class objects, StringBuffer class
		// objects can be modified after they are created.  We will look
		// more at the benefits of each later on.
		StringBuffer S1, S2;
		S1 = new StringBuffer("Hello");
		System.out.println("S1 is " + S1);
		// System.out.println("S2 is " + S2);  // This will give a compilation
		                                       // error
		S2 = S1;
		System.out.println("S2 is " + S2);

		S1.append(" there Java maestros!");
		System.out.println("S2 is " + S2);

		StringBuffer S3 = new StringBuffer("Hello there Java maestros!");
		if (S1 == S2)	// comparing references
			System.out.println(S1 + " == " + S2);
		if (S1 != S3)
			System.out.println(S1 + " != " + S3);
		if (S1.toString().equals(S3.toString()))  // comparing actual strings
			System.out.println(S1 + " equals " + S3);

		S1 = null;  // Now S1 cannot be accessed using the "dot" notation but
		            // S2 still refers to the same object
		// S1.append(" This is not allowed");
		S2.append(" This is ok");
		System.out.println("S1 is " + S1);
		System.out.println("S2 is " + S2);
	}

}