add Variant0.java for lab3

src/lab3/Lab3.java

@@ -0,0 +1,75 @@
+package lab3;
+
+public class Lab3 {
+    private static final int REPETITION_NUMBER = 10;
+    public static void main(String[] args) {
+        StringBuilder result = new StringBuilder();
+        for (int i = 0; i < REPETITION_NUMBER; i++) {
+//            result += Integer.toString(i);
+//            result += String.valueOf(i);
+            result.append(i);
+        }
+
+
+
+        /*float f = 1.1f;
+        double d = 2.2;
+//        f = (float) (f + d);
+        f += d;*/
+
+        String s = "ASD";
+
+        StringBuilder stringBuilder = new StringBuilder("ASD");
+        StringBuffer stringBuffer = new StringBuffer("ASD");
+
+        stringBuilder.append("A");
+        System.out.println(s.length());
+        System.out.println(stringBuilder.length());
+        System.out.println(stringBuffer.length());
+
+        System.out.println(s.endsWith("D"));
+//        System.out.println(stringBuilder.substring(stringBuilder.length() - 1).equals("A"));
+        System.out.println("A".equals(stringBuilder.substring(stringBuilder.length() - 1)));
+        System.out.println("A".equals(stringBuffer.substring(stringBuffer.length() - 1)));
+
+        String sNull = null;
+        System.out.println("A".equals(sNull));
+        System.out.println(sNull.equals("A"));
+
+        System.out.println(s.substring(2));
+        System.out.println(s.contains("AS"));
+
+        System.out.println(s.indexOf('a'));
+
+//        System.out.println(s.charAt(-1));
+
+        System.out.println("s.equalsIgnoreCase(\"AsD\") = " + s.equalsIgnoreCase("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";
+//        String s5 = new String("ASD");
+        String s5 = "AS";
+        s5 += "D";
+        System.out.println(s4 == s5); // true? (SP)
+        System.out.println(s4.equals(s5)); // (true)
+
+
+
+        System.out.println("Done!");
+    }
+}