類別建立 - 戶頭

AccountObject.java

/*

s4.(戶頭)
   實作一戶頭類別Account,內含私有餘額balance,型別實數,
   對外提供如下公開方法:
   	public Account(double initialBalance) //建構子,含初始餘額
   	public void credit(double amount) // 存款,含存款金額
   	public double getBalance() // 讀出餘額,回傳餘額
   測試時,可用建構子建立一個戶頭,初始餘額為50,先印餘額看對不對,
   再存入25,印餘額看對不對.

   註: 建構子若遇初始餘額<0,可一律設定為0.

s5.(承上)
   為戶頭類別新增如下提款方法:
   	public double debit(double amount)
   	// 自戶頭餘額扣掉amount金額,回傳實際扣掉金額
   	// 若戶頭餘額不足,不作扣款,印出"餘額不足"訊息,回傳金額為0
      
      
      Account account = new Account(100);
      // 印出初始金額
      // 存入 300 元
      // 印出當前餘額
      // 試圖提 600 元 印出餘額不足
      // 試圖提 200 元 印出提款 200 元
      // 印出餘額
*/

Homework

• 把 System.out.println 移出 Account

`/**

• Created by Jason.Yao on 2017/5/5.
• 初始金額: 100.0
  餘額: 100.0
  存款:300.0 餘額等於:400.0
  存款餘額:400.0 餘額不足:600.0
  提款: 200.0
  餘額: 200.0
  */

public class BackAccunt {

public static void main(String[] args) {
    int tocash = 0;
    System.out.print("初始金額: ");
    Account account = new Account(100);
    System.out.print("餘額:");
    System.out.println(account.getBalance());

    tocash = 300;
    System.out.println("存款:" + tocash);
    account.credit(tocash);
    System.out.println("餘額等於" + account.getBalance());

    tocash = 600;
    double balance = account.getBalance();
    if (tocash > balance) {
        System.out.print("存款餘額:" + balance + "   " + "餘額不足:");
        System.out.println(account.debit(tocash));

    } else {
        balance = balance - tocash;
        System.out.print("提款: ");
        System.out.println(account.debit(tocash));
        System.out.println(account.getBalance());
    }
    tocash = 200;
    double balance1 = account.getBalance();
    if (tocash > balance1) {
        System.out.print("存款餘額:" + balance + "   " + "餘額不足:");
        System.out.println(account.debit(tocash));

    } else {
        balance1 = balance1 - tocash;
        System.out.print("提款: ");
        System.out.println(account.debit(tocash));
        System.out.print("餘額:");
        System.out.println(account.getBalance());
    }
}

static class Account {
private double balance;

public Account(double initialBalnce){
    if (initialBalnce <= 0) {
        this.balance = 0;
        System.out.println(this.balance);
    }else{
        this.balance = initialBalnce;
        System.out.println(this.balance);
    }
}

public void credit(double amount){
    this.balance = this.balance + amount;
}

public  double getBalance(){
    return this.balance;
}

public double debit(double amount) {
        return amount;
    }
}

}`