Copy these into test classes to see if your code works.

/**
* Test the superclass BankAcct
*
**/
public class TestBankAcct
{
		// test driver program
       // Be sure BankAcct is not abstract for this test
	public static void main(String[] args) {
		BankAcct x;
		x = new BankAcct("A1234", 300.00);
		x.deposit(50.00);
		x.withdraw(20.00);
		System.out.println(x.getAcctNo() + " has $" +x.getBalance());
		// the balance should be A1234 has $330.00
	}
}



/**
 * test the checking account class
 */
public class TestCheckAcct
{
			// test driver program
	public static void main(String[] args) {
		CheckAcct x;
		x = new CheckAcct("B2234", 300.00);
		x.deposit(50.00);
		x.withdraw(20.00);
		System.out.println(x.getAcctNo() + " has $" +x.getBalance());
		// the balance should be B2234 has $329.50
	}
}



/**
 * test a savings account
 */
public class TestSavAcct
{
			// test driver program
	public static void main(String[] args) {
		SavAcct x;
		x = new SavAcct("C3334", 400.00, 0.05);// acct no, balance, rate
		x.deposit(100.00);
		x.withdraw(70.00);
		x.addInt();
		System.out.println(x.getAcctNo() + " has $" +x.getBalance());
		// lowbal=400
		// the balance should be C3334 has $400+100-70+20=$450.00
		SavAcct y;
		y = new SavAcct("C4131", 100.00, 0.025);
		y.withdraw(50.0); 
		y.deposit(50.0);
		y.addInt();
		System.out.println(y.getAcctNo() + " has $" +y.getBalance());
		//lowbal=50, bal=100, add interest 2.5%*50=$1.25
		// C4143 has $101.25
		//try to withdraw $150, balance goes down to 0, lowbal = 0
		y.withdraw(150.00);
		y.deposit(20.00);
		y.addInt();
		System.out.println(y.getAcctNo() + " has $" +y.getBalance());
		//since lowbal went down to 0, no interest
		// C4131 has $20.00
	}
}