add lab3

src/Lab3.java

@@ -0,0 +1,26 @@
+public class Lab3 {
+    public static void main(String[] args) {
+        String s = "ASD";
+        String s2 = s;
+        System.out.println("s2 = " + s2);
+        System.out.println(s == s2); // true?
+        System.out.println(s.equals(s2)); // true?
+        s += "B";
+        System.out.println(s);
+        System.out.println("s2 = " + s2);
+
+        System.out.println(s == s2); // false?
+        System.out.println(s.equals(s2)); // false?
+
+        String s3 = new String("ASD");
+        System.out.println(s3 == s2); // true? (false)
+        System.out.println(s3.equals(s2)); // false? (true)
+
+//      String Pool
+        String s4 = "ASD";
+        System.out.println(s4 == s2); // true?
+        System.out.println(s4.equals(s2)); // (true)
+
+        System.out.println("Done!");
+    }
+}