Java 编程练习：UML 图和源代码

4. 查找最大值

UML 图

源代码

import java.util.Scanner;

public class MaxNumber {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter a sequence of numbers (end with 0): ");
        int max = max(input);
        System.out.println("The maximum number is " + max);
    }

    public static int max(Scanner input) {
        int max = input.nextInt();
        while (input.hasNext()) {
            int number = input.nextInt();
            if (number == 0) {
                break;
            }
            if (number > max) {
                max = number;
            }
        }
        return max;
    }
}

11.5 课程管理

UML 图

源代码

import java.util.ArrayList;

public class Course {
    private String courseName;
    private ArrayList<String> students;
    private int numberOfStudents;

    public Course(String courseName) {
        this.courseName = courseName;
        students = new ArrayList<>();
    }

    public void addStudent(String student) {
        students.add(student);
        numberOfStudents++;
    }

    public String[] getStudents() {
        return (String[]) students.toArray(new String[students.size()]);
    }

    public int getNumberOfStudents() {
        return numberOfStudents;
    }

    public String getCourseName() {
        return courseName;
    }

    public void dropStudent(String student) {
        students.remove(student);
        numberOfStudents--;
    }
}

5. 银行账户管理

UML 图

源代码

import java.util.ArrayList;
import java.util.Date;

public class Account {
    private int id;
    private double balance;
    private double annualInterestRate;
    private Date dateCreated;
    private String name;
    private ArrayList<Transaction> transactions;

    public Account(int id, double balance, String name) {
        this.id = id;
        this.balance = balance;
        this.name = name;
        annualInterestRate = 0;
        dateCreated = new Date();
        transactions = new ArrayList<>();
    }

    public int getId() {
        return id;
    }

    public double getBalance() {
        return balance;
    }

    public double getAnnualInterestRate() {
        return annualInterestRate;
    }

    public Date getDateCreated() {
        return dateCreated;
    }

    public String getName() {
        return name;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setBalance(double balance) {
        this.balance = balance;
    }

    public void setAnnualInterestRate(double annualInterestRate) {
        this.annualInterestRate = annualInterestRate;
    }

    public double getMonthlyInterestRate() {
        return annualInterestRate / 12;
    }

    public double getMonthlyInterest() {
        return balance * getMonthlyInterestRate();
    }

    public void withdraw(double amount) {
        balance -= amount;
        transactions.add(new Transaction('W', amount, balance, "Withdrawal"));
    }

    public void deposit(double amount) {
        balance += amount;
        transactions.add(new Transaction('D', amount, balance, "Deposit"));
    }

    public ArrayList<Transaction> getTransactions() {
        return transactions;
    }
}

import java.util.ArrayList;

public class Transaction {
    private java.util.Date date;
    private char type;
    private double amount;
    private double balance;
    private String description;

    public Transaction(char type, double amount, double balance, String description) {
        date = new java.util.Date();
        this.type = type;
        this.amount = amount;
        this.balance = balance;
        this.description = description;
    }

    public java.util.Date getDate() {
        return date;
    }

    public char getType() {
        return type;
    }

    public double getAmount() {
        return amount;
    }

    public double getBalance() {
        return balance;
    }

    public String getDescription() {
        return description;
    }
}

public class TestAccount {
    public static void main(String[] args) {
        Account account = new Account(1122, 1000, "George");
        account.setAnnualInterestRate(1.5);
        account.deposit(30);
        account.deposit(40);
        account.deposit(50);
        account.withdraw(5);
        account.withdraw(4);
        account.withdraw(2);
        System.out.println("Account holder name: " + account.getName());
        System.out.println("Interest rate: " + account.getAnnualInterestRate() + "%");
        System.out.println("Balance: $" + account.getBalance());
        ArrayList<Transaction> transactions = account.getTransactions();
        System.out.printf("%-35s%-10s%-10s%-10s\n", "Date", "Type", "Amount", "Balance");
        for (Transaction transaction : transactions) {
            System.out.printf("%-35s%-10s%-10s%-10s\n", transaction.getDate(), transaction.getType(), transaction.getAmount(), transaction.getBalance());
        }
    }
}

6. 栈的实现

UML 图

源代码

import java.util.ArrayList;

public class MyStack extends ArrayList<Character> {
    public boolean isEmpty() {
        return super.isEmpty();
    }

    public int getSize() {
        return super.size();
    }

    public char peek() {
        return super.get(getSize() - 1);
    }

    public char pop() {
        char ch = super.get(getSize() - 1);
        super.remove(getSize() - 1);
        return ch;
    }

    public void push(char ch) {
        super.add(ch);
    }
}

import java.util.Scanner;

public class TestMyStack {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter five characters: ");
        String str = input.nextLine();
        MyStack stack = new MyStack();
        for (int i = 0; i < str.length(); i++) {
            stack.push(str.charAt(i));
        }
        System.out.print("The reversed string is ");
        while (!stack.isEmpty()) {
            System.out.print(stack.pop());
        }
    }
}