Week 1: Types, condition clauses and loops/4. Match expressions and results AND DATATYPE

Java's basic types
Type	Saved information	Number range
byte	integer	1 byte
short	integer	2 bytes
char	character	One Unicode-system character
int	    integer	4 bytes
long	integer	8 bytes
float	floating point number (i.e decimal number)	4 bytes
double	floating point number	8 bytes


eg
public class Example {
    public static void main(String[] args) {
        String name = "Mike Madeup";
        int age = 23;
        double height = 171.25;
    }
}



eg
// boolean (IN LOWERCASE) - true, false
public class Example {
    public static void main(String[] args) {
        boolean True = true;
        boolean False = false;
        boolean first_larger = 10 > 3;

        System.out.println(first_larger);
    }
}
Output:
true




eg
public class Example {
    public static void main(String[] args) {
        int first = 23;
        int second = 10;

        int multiply = first * second;
        int sum = first + second;

        int largeNum = (first + second) * 100;

        System.out.println(multiply);
        System.out.println(sum);
        System.out.println(largeNum); 
    }
}
Output:
230
33
3300







eg
//If there are several different types involved in an expression, the type of the result is determined by the "largest" type, for example:

public class Example {
    public static void main(String[] args) {
        int integer = 10;
        double float = 5.0;

        System.out.println(integer * 2);
        System.out.println(float * 2);
        System.out.println(integer * 2.0);
        System.out.println(integer + integer);
        System.out.println(integer + float);
    }
}
Output:
20
10.0
20.0 // int * float -> float
20
15.0 //int + float -> float






eg
//division
public class Example {
    public static void main(String[] args) {
        System.out.println(5 / 2);
        System.out.println(5 / 2.0);
        System.out.println(5.0 / 2);
        System.out.println(5.0 / 2.0);
    }
}
Output:
2      // int/int -> int
2.5    // int/float -> float
2.5    // float/int -> float
2.5    // float/float -> float






eg
public class Example {
    public static void main(String[] args) {
        int divided = 10;
        int divisor = 4;

        // This returns and integer...
        System.out.println(divided / divisor);

        // Result is wrong here too...
        double divide = divided / divisor;
        System.out.println(divide);

        //...but this works:
        System.out.println(divided * 1.0 / divisor);
    }
}
Output:
2     // int/int -> int (rounded down)
2.0   // int/int -> int (rounded down) -> then convert to double
2.5   // 'new' double/int -> double





eg
2 * (3 - 1)     4 
6/4             1 
2 * 3.0 + 1     7.0
2.0 * (3.0 - 1.0)   4.0
2 * 3 + 1       7
2 * (3 + 1)     8
2 * (3.0 + 1)   8.0
6/(2*2.0)       1.5