MasterJava.java

public class MasterJava{
    public static void main(String[] args){
        //Displaying text to console
        System.out.println("Hello World!");
        System.out.println("Hello student");


        //Escape sequence: use for breaking lines in text
        System.out.println("Oladipupo \nHassan");

        //Basic maths
        System.out.println(4+3);
        System.out.println(3-2);
        System.out.println(10/2);
        System.out.println(2*3);

        // Variable declaration and Assigning
        int myAge; //declaring variable
        myAge = 56; //Assigning Variable
        int myWeight = 800; // declaration and assigning
        System.out.println(myAge);
        System.out.println(myWeight);


        //Primitive Data types in Java

        //DataTypes For Whole Number: numbers with no decimal point

        //1. Byte: ranges -128 to 127
        byte newByte = 127;
        // 2.  Short : ranges -32,768 to 32,767
        short   newShort = 3287;
        // 3. Int: ranges -2, 147,483,648 to 2,147,483,647
        int newInt = 342455;
        //4. long
        long newLong = 300_00_00_000L;

        //DataTypes For Decimal Number: numbers with  decimal point

        //1. Float: store 32bits of floating point numbers
        float newFloat = 32.4f;

        // 2. Double: stores 64bits of double point number
        double newDouble = 3.14159665;

        //Data type Char: to store a single character
        char newChar = 'A';
        //Data type Boolean: to store value that are either true or false

        boolean isBoolean = true;
        boolean isPresent = false;
        System.out.println(isPresent);

        //String data type for storing string

        String greeting = "Hello Java";
        String cargo = "new ship";
        System.out.println(greeting);

        //Arithmetics with Variables
        int a = 10;
        int b = 5;
        int sum = a + b;
        System.out.println("The sum is : " + sum);
        int difference = a - b;
        System.out.println("The difference is : " + difference);



        //TypeCasting, it involves converting one data type to another
        // 1. Implicit typecasting: convert from smaller data type value to bigger data type  value and it happens automatically and no data lost
        int intNumber = 14;
        double doubleNumber = intNumber;
        System.out.println(doubleNumber);

        // 2. explicit typecasting: convert from bigger data type value to smaller data type  value and it happens manually and result to loss of data

        double doubleNumber2 = 45.6;
        int intNumber2 = (int) doubleNumber2;
        System.out.println(intNumber2);


        double shapeValue = 78.9;
        System.out.println("The current shape value is :"  + shapeValue);

        int intConvert = (int) shapeValue;

        System.out.println("The current shape value is :"  + intConvert);

        double doubleConvert = (double) intConvert;

        System.out.println("The current shape value is :"  + doubleConvert);

        float floatConvert = (float) doubleConvert;

        System.out.println("The current shape value is :"  + floatConvert);

        long longConvert = (long) floatConvert;

        System.out.println("The current shape value is :"  + longConvert);


        //Operators: special symbol use to perform operation on variables

        //Type
        //1.  Modulo operators: gives remainder value after division

        int num1 = 8;
        int num2 = 3;

        int resultModulo = num1 % num2;
        System.out.println("The result is: " + resultModulo);

        //2. Unary
        int num3 =+5;
        int num4 =-5;

        //3. Post Increment: Increase the value of the variable by one after re-assigning

        int num5 = 10;
        int num6 = num5++;
        System.out.println("Post Increment");
        System.out.println("num5 is : " + num5);
        System.out.println("num6 is : " + num6);

        //4. Pre Increment: Increase the value of the variable by one before re-assigning

        int num7 = 10;
        int num8 = ++num7;
        System.out.println("Pre Increment");
        System.out.println("num7 is : " + num7);
        System.out.println("num8 is : " + num8);


        //5. Post Decrement: decrease the value of the variable by one after re-assigning

        int num9 = 15;
        int num10 = num9++;
        System.out.println("Post Decrement");
        System.out.println("num9 is : " + num9);
        System.out.println("num10 is : " + num10);

        //6. Pre Decrement: Decrease the value of the variable by one before re-assigning

        int num11 = 17;
        int num12 = ++num11;
        System.out.println("Pre Decrement");
        System.out.println("num11 is : " + num11);
        System.out.println("num12 is : " + num12);

        //Relational Operators: use to perform comparison between two values

        //1 Equal to (==)
        int newNum1 = 10;
        int newNum2 = 5;
        boolean resultNum12 = (newNum1 == newNum2);
        System.out.println("is newNum1 equal newNum2 ? : " + resultNum12);


        //1 Not Equal to (!=)
        int newNum3 = 10;
        int newNum4 = 5;
        boolean resultNum34 = (newNum3  != newNum4);
        System.out.println("is newNum3 not equal newNum2 ? : " + resultNum34);




        //3 greater than (>)
        int newNum5 = 10;
        int newNum6 = 5;
        boolean resultNum56 = (newNum5 >  newNum6);
        System.out.println("is newNum5 greater than newNum6 ? : " + resultNum56);

        //4 greater than or equal to  (>=)
        int newNum7 = 10;
        int newNum8 = 5;
        boolean resultNum78 = (newNum7 >=  newNum8);
        System.out.println("is newNum7 greater or  equal newNum8 ? : " + resultNum78);


        //5 less  than (<)
        int newNum9 = 10;
        int newNum10 = 5;
        boolean resultNum109 = (newNum9 <  newNum10);
        System.out.println("is newNum9 less than newNum10 ? : " + resultNum109);

        //4 less than or equal to  (<=)
        int newNum11 = 10;
        int newNum12 = 5;
        boolean resultNum1112 = (newNum11 <=  newNum12);
        System.out.println("is newNum11 less or  equal newNum12 ? : " + resultNum1112);


        //Compound Operators

        //1. Additional assignment: use to add value at the left to the variable at the right

        int operaNum1 = 4;
        System.out.println("The result of operaNum1 before addition assignment is :" + operaNum1);
        operaNum1 +=  3;
        System.out.println("The result of operaNum1 after addition assignment is :" + operaNum1);

        //2. Subtraction assignment: use to subtract value at the left from the variable at the right

        int operaNum2 = 4;
        System.out.println("The result of operaNum2 before subtraction assignment is :" + operaNum2);
        operaNum2 -=  3;
        System.out.println("The result of operaNum2 after subtraction assignment is :" + operaNum2);

        //3. Multiplication assignment: use to multiply value at the left to the variable at the right

        int operaNum3 = 4;
        System.out.println("The result of operaNum2 before multiplication assignment is :" + operaNum3);
        operaNum3 *=  3;
        System.out.println("The result of operaNum2 after addition multiplication assignment is :" + operaNum3);

        //4. Division assignment: use to divide value at the left by the variable at the right

        int operaNum4 = 4;
        System.out.println("The result of operaNum2 before division assignment is :" + operaNum4);
        operaNum4 /=  2;
        System.out.println("The result of operaNum2 after division assignment :" + operaNum4);



        // String: represent a sequence of character.

        // Creating string using sting literal
        String morning = "Good morning";
        System.out.println(morning);

        // Creating string using the "new" keyword
        String night = new String("Good night");
        System.out.println(night);

        // Concatenation: Joining two or more string, string can also be concatenated with number nut the number will be converted to string automatically

        //  Concatenating string
        String firstName = "Hassan";
        String lastName = new String("Oladipupo");
        String fullName = firstName + " " + lastName;
        System.out.println(fullName);

        //  Concatenating string with numbers
        int age = 26;
        String bio = "My name is "  + fullName + "and i am "  + age + " years old" ;
        System.out.println(bio);

        // String method Length: use to get the length of a string
        String quote = "Determination is the Key";
        int quoteLength = quote.length();
        System.out.println(quoteLength);

        // String method charAt: use to get specific character  at specific index
        String newQuote = "Motivation is the Key";
        char firstChar = newQuote.charAt(0);
        System.out.println(firstChar);

        // Comparing string with (==): this compare every details of the strings , this is know as comparing with reference

        // Comparing Reference : memory Address
        String str1 = "javaScript";
        String str2 = "javaScript";
        String str3 = new String("javaScript");

        boolean compareStr12 = (str1 == str2);
        System.out.println("Comparing " + str1 + " with " + str2 + " using == " + " and the result is: " + compareStr12);

        boolean compareStr13 = (str1 == str3);
        System.out.println("Comparing " + str1 + " with " + str3 + " using == " + " and the result is: " + compareStr13);

        // Comparing string with (equals): this compare only values of variables

        // Comparing variables value

        String str4 = "Java";
        String str5 = "Java";
        String str6 = new String("Java");

        boolean compareStr45 = (str4.equals(str5));
        System.out.println("Comparing " + str4 + " with " + str5 + " using equals() " + " and the result is: " + compareStr45);

        boolean compareStr46 = (str4.equals(str6));
        System.out.println("Comparing " + str4 + " with " + str6 + " using equals() " + " and the result is: " + compareStr46);


        // Comparing string with (equalsIgnoreCase): this compare only values of variables without case sensitivity

        // Comparing variables value  without case sensitivity

        String str7 = "Php";
        String str8 = "php";
        String str9 = new String("phP");

        boolean compareStr78 = (str7.equalsIgnoreCase(str8));
        System.out.println("Comparing " + str7 + " with " + str8 + " using equalsIgnorecase() " + " and the result is: " + compareStr78);

        boolean compareStr79 = (str7.equalsIgnoreCase(str9));
        System.out.println("Comparing " + str7 + " with " + str9 + " using equalsIgnoreCase() " + " and the result is: " + compareStr79);

        // Cutting string : this involves breaking string in to different part using substring() method

        String phrase1 = "programming in java";
        String word1 = phrase1.substring(0,11);
        System.out.println(word1);

        String phrase2 = "programming in python";
        String word2 = phrase2.substring(15);
        System.out.println(word2);

        // replace method(): use to replace a character in a string with another one
        String phrase3 = "Tap level pragrammer";
        String replaceLetter = phrase3.replace('a', 'o');
        System.out.println(replaceLetter);

        // toUpperCase  method(): use to change lower letter to upper case
        String phrase4 = "Top level programmer";
        String upperLetter = phrase4.toUpperCase();
        System.out.println(upperLetter);

        // toLowerCase  method(): use to change upper letter to lower case
        String phrase5 = "TOP LEVEL PROGRAMMER";
        String lowerLetter = phrase5.toLowerCase();
        System.out.println(lowerLetter);

        

    }


}