Thread: Help for write Bank application in Java

Hi.
I'm a student and I need write a programe bank application in java .
I must write a program that the customer could withdraw and deposit from his account.I wrote this program.
but I need to use several classes for this program (object oriented). for exemple:
BankAccount which has an instance variable amount
and has methods:
withDraw which takes a parameter -> amountToWithDraw
deposit -> amountToAdd
checkBalance -> which takes no parameters, but which returns the value in the instance variable amount.
but i dont know how use of several classes.
you can help me?

import java.util.Scanner;
 
public class BankAccount {
public static void main(String[] args) {
 
Scanner clapton=new Scanner(System.in);
int x;
float balance = 0;
boolean quit=false;
do {
System.out.println("1. Deposit money");
 
System.out.println("2. Withdraw money");
 
System.out.println("3. Check balance");
 
System.out.print(" 0 to quit: ");
 
System.out.println("enter your choice :");
 
x=clapton.nextInt();
if (x==1) {
 
float amount;
System.out.println(" Amount to deposit :");
amount=clapton.nextFloat();
if (amount>=0) {
balance += amount;
}
else {
System.out.println("system can't reply your request");
}
 
}
else if (x==2) {
float amount;
System.out.println(" Amount to withdraw :");
amount =clapton.nextFloat();
if (amount<=0 || amount > balance) {
System.out.println("system can't reply your request ");
 
}
else {
balance -= amount;
}
}
else if (x==3) {
System.out.println("your balance :" + balance );
}
else if (x==0) {
quit=true;
}
else {
System.out.println("wrong choice");
}
}
while (!quit);
System.out.println("bye");
}
}

but i dont know how use of several classes.
you can help me?

Don't worry, hang on... To use a class from another class, create a new instance of the class using new keyword, then use dot operator on the instance to invoke methods of the class. For example:

class A {
    void foo() {}
}
 
class B {
    // invoke foo() method of class A:
    public void useA() {
        A a = new A();
        a.foo();
    }
}