Programming in Java assignment help

Write any FOUR questions (each question carries equal marks)
1. Write a Java program to calculate area of the circle using radius input by the user.
2. Write a Java program to generate prime numbers between 1 and a given number input by the user.
3. Write a program to convert given no. of days into months and days. (Assume that each month is of 30 days).
4. Write a program in JAVA to determine whether a calendar year is a leap year or not.
5. Write a program to check a string is palindrome or not.
6. Write a program to perform to the extend operation with class.