unit2_1_1.java

public class unit2_1_1 {
    public static void main(String[] args) {
        // Example 1
        String a = "bicycle";
        String b = a;

        System.out.println("a: " + a + ", b: " + b);

        // Example 2
        String c = new String("bicycle");
        String d = c;

        System.out.println("c: " + c + ", d: " + d);

        System.out.println("a ref: " + a.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(a)));
        System.out.println("b ref: " + b.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(b)));
        System.out.println("c ref: " + c.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(c)));
        System.out.println("d ref: " + d.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(d)));
    
        // Print null values
        String color = null;
        System.out.println("color: " + color);

        // Changing String (or object)
        String word1 = "Ball";
        System.out.println("word1: " + word1 + ", word1 ref: " + a.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(word1)));
        
        String word2 = word1 + "oon";
        System.out.println("word2: " + word2 + ", word2 ref: " + a.getClass().getName() + "@" + Integer.toHexString(System.identityHashCode(word2)));

        // Compare Strings
        System.out.println("a == b? : " + (a == b));
        System.out.println("a == c? : " + (a == c));
        System.out.println("c == d? : " + (c == d));

        System.out.println("a.equals(b)? : " + (a.equals(b)));
        System.out.println("a.equals(c)? : " + (a.equals(c)));
        System.out.println("c.equals(d)? : " + (c.equals(d)));

        // Substring
        // Examples:
        // "hamburger".substring(4, 8) returns "urge" =: 4 < index < 8
        // "smiles".substring(1, 5) returns "mile" =: 1 < index < 5
        //
        System.out.println("a.substring(0,3): " + a.substring(0, 3));
        System.out.println("a.substring(3): " + a.substring(3));
    }
}