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