使用方法改变Java中Object的Static变量的值

Question

I am trying to create an ATM in Java using methods. I am trying to call methods that change the variable (total) of the object (balance). I have successfully created the object and set its starting value but I can't figure out how to create a method that alters that methods. I am not sure how setters and getters would apply because everything is static. Any suggestions?

enter image description here

Answer 1

Your setter and getter could look like in the following snippet. I set total to private as it should only be accessible by the setter and getter functions. You can then set your value by startVal.setTotal(100);

class balance {

    private int total;

    int getTotal() {
        return total;
    }

    void setTotal(int total) {
        this.total = total;
    } 

}

Answer 2

You can do like this:

import java.util.Scanner;
class Main {

private static Scanner in;
private static Balance balance;

public static void main (String[] args) {
  in = new Scanner(System.in);
  balance = new Balance();

  while(true) {
    System.out.println("Main menu:");
    System.out.println("1. Check Balance");
    System.out.println("2. Withdraw");
    System.out.println("3. Deposite");
    System.out.println("4. Exit");

    int n = in.nextInt();

    switch (n) {
      case 1 : displayBalance();
               break;
      case 2 : withdraw();
               break;
      case 3 : deposite();
               break;
      default : return;
    }
  }
}

private static void displayBalance() {
  System.out.println(balance.getBalance());
}

private static void withdraw() {
  double currentBalance = balance.getBalance();

  System.out.println("Enter amount to be withdrawn : ");
  double withdrawAmount = in.nextDouble();
  double balanceAfterWithdraw = currentBalance - withdrawAmount;

  if (balanceAfterWithdraw > 0) {
    balance.setBalance(balanceAfterWithdraw);
    System.out.println(withdrawAmount + " withdrawn.");
    System.out.println("Your new balance is : " + balance.getBalance());
  } else
    System.out.println("You don't have sufficient balance !!!");
}

private static void deposite() {
  double currentBalance = balance.getBalance();

  System.out.println("Enter amount to deposit : ");
  double depositeAmount = in.nextDouble();
  double balanceAfterDeposit = currentBalance + depositeAmount;

  balance.setBalance(balanceAfterDeposit);
  System.out.println(depositeAmount + " deposited.");
  System.out.println("Your new balance is : " + balance.getBalance());
  }
}


public class Balance {

  private double balance;

  public Balance() {
    this.balance = 100;
  }

  public double getBalance() {
    return balance;
  }

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

}