Java Technology

Write a program to find 9th higest salary.

SELECT empSal
FROM (
SELECT empSal,
DENSE_RANK() OVER (ORDER BY empSal DESC) AS rnk
FROM employee
)
WHERE rnk = 9;

package java8;

import java.util.Arrays;
import java.util.Comparator;

public class ArraysOfString {

public static void main(String[] args) {
String[] arr = {"aa", "a", "bb", "ccc"};
Arrays.stream(arr)
.sorted(Comparator.comparing(String::length))
.forEach(System.out::println);

}
}

o/p : a aa bb ccc

Wap to check string is anagram?
package java8;

import java.util.Arrays;
import java.util.Map;
import java.util.function.Function;
import java.util.stream.Collectors;

public class AnagramLambda {


public static void main(String[] args) {

String s1 = "geeks";
String s2 = "kseeg";

Map map1 = s1.chars()
.mapToObj(c -> (char) c)
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));

Map map2 = s2.chars()
.mapToObj(c -> (char) c)
.collect(Collectors.groupingBy(Function.identity(), Collectors.counting()));


System.out.println(map1.equals(map2) ? "Anagram" : "Not Anagram");



boolean isAnagram =
Arrays.equals(
s1.chars().sorted().toArray(),
s2.chars().sorted().toArray()
);

System.out.println(isAnagram ? "Anagram" : "Not Anagram");


}
}

Sql Query
========================================

1. Write a query to find the second highest salary in the employees table.
SELECT MAX(SALARY)
FROM HR.EMPLOYEES
WHERE SALARY NOT IN (SELECT MAX(SALARY) FROM HR.EMPLOYEES);
2. Write a query to find the second highest salary using a < condition.
SELECT MAX(SALARY)
FROM HR.EMPLOYEES
WHERE SALARY < (SELECT MAX(SALARY) FROM HR.EMPLOYEES);
________________________________________
Aggregate Functions by Department
3. Write a query to display the maximum salary in each department.
SELECT MAX(SALARY), DEPARTMENT_ID
FROM HR.EMPLOYEES
GROUP BY DEPARTMENT_ID;
4. Write a query to display the minimum salary in each department.
SELECT MIN(SALARY), DEPARTMENT_ID
FROM HR.EMPLOYEES
GROUP BY DEPARTMENT_ID;
5. Write a query to display the number of employees in each department.
SELECT COUNT(*), DEPARTMENT_ID
FROM HR.EMPLOYEES
GROUP BY DEPARTMENT_ID;
________________________________________
Odd and Even Rows
6. Write a query to display all employees with odd-numbered rows using ROWNUM.
SELECT *
FROM (
SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, ROWNUM RN
FROM HR.EMPLOYEES ORDER BY RN
)
WHERE MOD(RN,2) != 0;
7. Write a query to display all employees with even-numbered rows using ROWNUM.
SELECT *
FROM (
SELECT EMPLOYEE_ID, FIRST_NAME, LAST_NAME, EMAIL, ROWNUM RN
FROM HR.EMPLOYEES ORDER BY RN
)
WHERE MOD(RN,2) = 0;
________________________________________
Grouping by Names
8. Write a query to display the count of each first name, ordered by frequency.
SELECT FIRST_NAME, COUNT(*)
FROM HR.EMPLOYEES
GROUP BY FIRST_NAME
ORDER BY COUNT(*);
9. Write a query to display only those first names that occur more than once.
SELECT FIRST_NAME, COUNT(*)
FROM HR.EMPLOYEES
GROUP BY FIRST_NAME
HAVING COUNT(*) > 1;
________________________________________
Pattern Matching with LIKE
10. Display the first names that start with ‘D’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE 'D%';
11. Display the first names that end with ‘n’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE '%n';
12. Display the first names that contain the letter ‘r’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE '%r%';
13. Display the first names that do not contain the letter ‘r’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME NOT LIKE '%r%';
14. Display the first names that are exactly 4 characters long.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE '____';
15. Display the first names where the second character is ‘o’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE '_o%';
16. Display the first names where the fourth character is ‘m’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE '___m%';
17. Display the first names that contain the substring ‘ll’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE '%ll%';
18. Display the first names that start with ‘R’ and end with ‘l’.
SELECT FIRST_NAME FROM HR.EMPLOYEES WHERE FIRST_NAME LIKE 'R%l';
________________________________________
Filtering by Hire Date
19. Write a query to display employees hired on 17-June-2013, by formatting the hire date and using LIKE.
SELECT FIRST_NAME, HIRE_DATE
FROM HR.EMPLOYEES
WHERE TO_CHAR(HIRE_DATE, 'MM/DD/YYYY, HH:MI:SS AM') LIKE '06/17/2013%';
20. Write a query to display employees hired exactly on 17-June-2013 using TO_DATE.
SELECT FIRST_NAME, HIRE_DATE
FROM HR.EMPLOYEES
WHERE HIRE_DATE = TO_DATE('2013-06-17', 'YYYY-MM-DD');

open this link for practice.

Oracle Live SQL

try-catch-finally with return in Java

Case 1: return in try, but finally executes

public class Test {
public static int testMethod() {
try {
System.out.println("Inside try");
return 1;
} catch (Exception e) {
System.out.println("Inside catch");
return 2;
} finally {
System.out.println("Inside finally");
}
}

public static void main(String[] args) {
System.out.println("Result = " + testMethod());
}
}
//output
Inside try
Inside finally
Result = 1

Case 2: return in finally (overrides try/catch)

public class Test {
public static int testMethod() {
try {
System.out.println("Inside try");
return 1;
} catch (Exception e) {
System.out.println("Inside catch");
return 2;
} finally {
System.out.println("Inside finally");
return 3;
}
}

public static void main(String[] args) {
System.out.println("Result = " + testMethod());
}
}
//output
Inside try
Inside finally
Result = 3

Note : If you return inside finally, it overrides any previous return.

Case 3: Exception occurs in try

public class Test {
public static int testMethod() {
try {
int x = 10 / 0; // Exception
return 1;
} catch (Exception e) {
System.out.println("Inside catch");
return 2;
} finally {
System.out.println("Inside finally");
}
}

public static void main(String[] args) {
System.out.println("Result = " + testMethod());
}
}

//Output:
Inside catch
Inside finally
Result = 2

Catch handled the exception, finally executed, then return value from catch.

Golden Rules to remember (interview points):
1. finally always executes (except System.exit or JVM crash).
2. If finally has a return statement, it overrides try/catch returns.
3. Avoid return inside finally → makes debugging very confusing.

Case 4: Using System.exit() inside try

public class Test {
public static int testMethod() {
try {
System.out.println("Inside try");
System.exit(0); // Terminates JVM immediately
return 1;
} catch (Exception e) {
System.out.println("Inside catch");
return 2;
} finally {
System.out.println("Inside finally");
return 3;
}
}

public static void main(String[] args) {
System.out.println("Result = " + testMethod());
}
}
//output
Inside try
After printing "Inside try", the JVM shuts down.
• finally is NOT executed.
• The return statement is never reached.

Case 5: Using System.exit() inside catch
public class Test {
public static int testMethod() {
try {
int x = 10 / 0; // ArithmeticException
return 1;
} catch (Exception e) {
System.out.println("Inside catch");
System.exit(0); // JVM shuts down here
return 2;
} finally {
System.out.println("Inside finally");
return 3;
}
}

public static void main(String[] args) {
System.out.println("Result = " + testMethod());
}
}

//output
Inside catch

Again, finally is skipped because JVM exits immediately.

Key Interview Notes:
• Normally, finally always executes.
• But two exceptions:
1. If JVM terminates abnormally (e.g., crash, kill -9).
2. If you explicitly call System.exit() → JVM shuts down, so finally is skipped.

All important points about try-catch-finally with return in Java
• If return is inside try, the expression is evaluated, but finally always executes before returning.
• If return is inside catch, same rule — finally executes before returning.
• If finally contains no return, then the value from try/catch is returned after finally finishes.
• If finally itself has a return, that overrides and discards any previous return from try/catch.
• If finally modifies a variable (but does not return), the evaluated return value from try/catch remains unchanged.
• If System.exit(0) (or JVM crash) happens in try/catch, then finally does not execute.
• So rule of thumb: finally block always executes (except JVM termination), and its return (if present) takes highest priority.