JPA 1 - Module 2: Java Core - Classes, Objects, Variables and Methods

Notes: 

https://javajee.com/book/java-core-classes-objects-variables-and-methods

Module 2.1: Data Types and Variables

Exercises

  1. Write a program with static, instance and local variables.

    1. Write a class that has 2 variables of type int: myStaticVar, myInstanceVar and myLocalVar as a static instance and local variable respectively.

    2. Assign values to static and instance variables through appropriate initialization blocks, and local variable within the method where it is defined.

    3. Print their values from main method in most appropriate way.

  2. Write a program to demonstrate static import.

    1. Create class Abc in package com.javajee.examples.First with a static variable myStaticVar.

    2. Assign it a value of 10. 

    3. Create another class Def in the package com.javajee.examples.second.

    4. Import myStaticVar of class Abc through static import and print its value from a main method.

Question sets:

With answers: set-4set-6

Without answers: set-5

Module 2.1: methods and constructors

Exercises

  1. Create a Calculator class.

    1. Create a class Calculator with two static methods add and subtract, that accept two integers and does addition/subtraction and return an integer result.  

    2. Pass values, get the result and print them all from main method.

Question sets:

With answers: set-7set-9

Without answers: set-8

Module 2.3: Overloading methods and constructors

Exercises

  1. Create a class with overloaded constructors.

    1. Create a class with two overloaded constructors: one that accept an int and other that accept two int.

    2. Invoke the one that accept only one int from the main method for creating an object.

    3. The constructor should then call the other constructor passing in the passed in argument as the first argument and some default value for the second argument.

    4. Constructor 1 should print "I am constructor that accept an int: value" where value is the value passed in and constructor 2 should print "I am a constructor that accept two int: value1, value2" where value1 and value2 are the values passed in as parameters.

Question sets:

With answers: set-10

Without answers: set-11

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