2 KiB
Lecture for January 30
Random Number Generator
One of the ways you can do a random number generator is through this method:
Import a class called random
import java.util.Random;
Then you need to create a Random object
Random rand = new Random();
After this you can call the nextInt() method to get a random number between 0 and 2^{32}
int randInt = rand.nextInt();
If you don't want a random number between 0 and 2^{32} but instead to another maximum value, then you can call the nextInt method inserting the max integer as a parameter.
Random Integer from 0-10 (not including 10)
int randInt2 = rand.nextInt(10);
Output
We have already encountered System.out.println and System.out.print but let us go over the differences again.
System.out.println() prints the contents inside the parenthesis and appends a newline character afterwards so that the next output is on a new line
System.out.print() prints the contents inside the parenthesis and does not output a newline character
Formatting Output
If you want more control on how your output is displayed, it is recommended that you use System.out.printf to format your output
First, you need to specify your type using the % instruction
- d for integer
- f for decimal
Example:
int sum = 50;
System.out.printf("Total = %d", sum);
This outputs
Total = 50
Notice here that there is no concatenation required like the previous two methods, instead you insert the variables as parameters
Let us deconstruct the % instruction
% __ __ . __ __
The first underline is the + - 0 space (sometimes we want to pad the money with zeros)
The second underline is the width of the text
The third underline is the number of decimal places
The the final underline is the specifier f for decimal and d for integer
Example
double amount = 0.5;
System.out.printf("Total Due: %0.2f")
This outputs
Total Due: 0.50