1. Example: Finding the Mode
Given: A sequence of integers
Goal: Determine the mod of the set
The number which appears the most number of times

2. Example: Finding the Mode
Algorithm:
Generate an array of 100 random numbers from 1 to 10
Use a length 10 array to count how many times each number appears in the array
Report the one that appears the most, or multiple if there are ties

3. exceptions
Motivation: it would be nice to “monitor” the flow of a program for certain bugs
Invalid input
Invalid array access
Type mismatches
Recall the example of trying to validate a user input, ensuring that they enter a positive integer
Requires slightly confusing loop logic to manage each case
Use Scanner.hasNextInt(), etc.

4. Exceptions Example: int x;
x = “1”; // “throws” a NumberFormatException
int[] myArray = new int[5];
myArray[5] = 1; // “throws” a ArrayIndexOutOfBoundsException

5. exceptions If a program raises an exception, it crashes!
… unless we “catch” it!
Syntax: the “try…catch” block

6. Try ... Catch Syntax: try { <statements-1>
} catch ( <exception-class-name> <variable-name> ) {
<statements-2> }
We can also chain more “catch” blocks for different types of exceptions

7. Try…catch
Behavior: if the code inside the “try” block raises an exception that matches an exception in the “catch” block, it will immediately stop executing the “try” and start executing the “catch” block
int[] myArray = new int[100];
try {
myArray[100] = 1;
} catch ( ArrayIndexOutOfBoundsException e ){
System.out.println(“You accessed an invalid element!”); }

8. Example: Input Validation
Ask the user for an array of integers, validate each
Print the average of the array