feat: add solutions for sl_5, sl_6, sl_7 and fix scanner in sl_3, sl_4

sl_3/AddNumbers.java

@@ -8,5 +8,6 @@ public static void main(String[] args) {
         System.out.print("Enter second number: ");
         int b = sc.nextInt();
         System.out.println("Sum: " + (a + b));
+        sc.close();
     }
 }

sl_4/LeapYear.java

@@ -11,5 +11,6 @@ public static void main(String[] args) {
         } else {
             System.out.println(year + " is not a leap year.");
         }
+        sc.close();
     }
 }

sl_5/ShiftOperation.java

@@ -0,0 +1,14 @@
+import java.util.Scanner;
+
+public class ShiftOperation {
+    public static void main(String[] args) {
+        Scanner sc = new Scanner(System.in);
+
+        System.out.print("Enter a number: ");
+        int n = sc.nextInt();
+
+        System.out.println("Multiply by 4: " + (n << 2));
+        System.out.println("Divide by 4: " + (n >> 2));
+        sc.close();
+    }
+}

sl_6/Swap.java

@@ -0,0 +1,12 @@
+public class Swap {
+    public static void main(String[] args) {
+        int a = 10, b = 20;
+
+        a = a ^ b;
+        b = a ^ b;
+        a = a ^ b;
+
+        System.out.println("a = " + a);
+        System.out.println("b = " + b);
+    }
+}

sl_7/Convert.java

@@ -0,0 +1,9 @@
+public class Convert {
+    public static void main(String[] args) {
+        long l = 1000L;
+        int i = (int) l;
+
+        System.out.println("Long: " + l);
+        System.out.println("Int: " + i);
+    }
+}