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public class DigitalWallet {

    private static double maxWithdrawalPct = .5;

    private long accountId;
    private long balance = 0;
    private TransactionHistory transactions = new TransactionHistory();

    public DigitalWallet(long accountId) {
        this.accountId = accountId;

rshepherd

public class Constructors {

    // Constructors initializes a class for use
    // They must have the same name as the name of the class
    public static class Cube {

        // You can provide initial values for your instance variables like so
        // (You don't necessarily need to do this in a constructor)
        private int length = 1;
        private int width = 1;

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public class Scoping {  // class scope begins

    // Because 'a' is declared just inside the *class curly braces* it is in 'class scope'
    // therefore its visible everywhere inside the class. This is the 'widest' scope in this file.
    private int a = 0;
    
    // Class variables have class scope!
    private static String classVariable = "I am a class variable!";

    public void methodOne() {  // methodOne scope begins

rshepherd

// Question 1
public static boolean isVowell(char letter) {
    switch (letter) {
        case 'a':
        case 'e':
        case 'i':
        case 'o':
        case 'u':
            return true;
        case 'y':

rshepherd

import java.util.Arrays;

public class Methods {

    public static void main(String[] args) {

        // Methods are just functions that belong to a particular class

        // Methods are sub-routines. Reusable code.
        // Method have parameters, are called with arguments

rshepherd

public class FizzBuzz {
    public static void main(String[] args) {
        for(int i = 0 ; i < 100 ; ++i) {
            boolean fizz = i % 3 == 0;
            boolean buzz = i % 5 == 0;
            if (fizz && buzz) {
                System.out.println("FizzBuzz");
            } else if (fizz) {
                System.out.println("Fizz");
            } else if (buzz) {

rshepherd

import java.util.ArrayList;
import java.util.List;

public class ForEach {

    public static void main(String[] args) {

        // Let's say we have a plain old array, like this one.
        char[] array = "This is a character array.".toCharArray();

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public class ListBasedQueue<T> implements Queue<T>
{
    private Node<T> first;      // beginning of queue
    private Node<T> last;       // For efficiency, maintain a reference to the least-recently added Node on the queue.

    public ListBasedQueue() {
        first = null;
        last = null;
    }

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import java.util.ArrayList;
import java.util.List;

public class ExpressionParser {

    public static void main(String[] arg) {
        // Assume the entered expression has only the expected characters otherwise they are ignored
        String input = "(400+8) * (6-5)/((311-2) *(2+2)) xxx";

        // Parse input

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public class ListBasedStack<T> implements Stack<T>
{
    private Node<T> top = null;

    public boolean isEmpty()
    {
        return top == null;
    }

    public void clear()