Exception in thread "main" java.lang.Error: Unresolved compilation problems(String)

Question

The final code looks like this. Fixed the errors and understood the concepts of inheritance. Thanks to you guys who responded to my post. Your replies were helpful.

Account Class

public class Account {
String name;
String number;
public double balance;


public class Account 
{
public String acctnum;
public String accttitle;
public Double acctbal;
public String accttitle2;
public Account()
{
}
public void withdraw(Double amount)
{
 acctbal=acctbal-amount;
}
public void deposit(Double amount)
{
  acctbal=acctbal+amount;    
}
public double zakat() /*In Islam Zakat is deducted every year from saving 
                        accounts in holy month of Ramadan  */
{
 Double z=acctbal*0.025;
 return z;
}
 public void showdetail()
{
 System.out.println("The Account Number  ="+acctnum);
 System.out.println("The Account Title   ="+accttitle);
 System.out.println("The Account Balance ="+acctbal);  
}
}

Current Account Class

public class CurrentAccount extends Account
{   
  public CurrentAccount(String Num,String Title,double Bal)
{
 acctnum = Num;
 accttitle = Title;
 acctbal = Bal;
}
public double tax()
{
double t= acctbal*0.05;
return t;        
}
}

Joint Account Class

public class JointAccount extends Account
{
public String accttitle2;
public JointAccount(String Num,String Title,String accttitle_1,double Bal)
{
  acctnum = Num;
  accttitle=Title;
  accttitle2=accttitle_1;
  acctbal  =Bal;
}
 public void showdetail()  //Overrding
{
System.out.println("The Account Number  = " + acctnum);
System.out.println("The Account Title   = " + accttitle + " and " + accttitle2);
System.out.println("The Account Balance = " + acctbal);
}
public double calculatetax()
{
 double t= acctbal*0.09;
 return t;
}
}

SavingAccount Class

public class savingAccount extends Account 
{
  public savingAccount(String Num,String Title,Double Bal)
{
  super.acctnum  =Num;
  super.accttitle=Title;
  super.acctbal  =Bal;
}
public double tax()
{
double t= acctbal*0.07;
return t;
}
public void withdraw(double amount)
{
   super.withdraw(amount);
     if(acctbal<1000){
     acctbal=acctbal-150;
 }
}

}

Following is testApp class

public class testApp 
{
public static void main(String args[])
{
savingAccount obj=new savingAccount("01-102-33","Ali",30000.0); 

System.out.println("My Balance is="+obj.acctbal);
obj.withdraw(5000.0);
System.out.println("After Withdraw The Balanc is="+obj.acctbal); 

obj.deposit(10000.0);
System.out.println("After deposit balance is  ="+obj.acctbal); 

double z= obj.zakat();
System.out.println("zakat is="+z); 

obj.withdraw(z);
System.out.println("after draw balance is="+obj.acctbal);

double t=obj.tax();
System.out.println("Tax is="+t);

obj.withdraw(t);
System.out.println("Remaining balance is ="+obj.acctbal);
obj.withdraw(25000.0);
obj.showdetail();

CurrentAccount obj1=new CurrentAccount("01-102-33","Ali",10000.0);
System.out.println("My Balance is="+obj1.acctbal);
t=obj1.tax();
System.out.println("Tax is ="+t);

obj1.withdraw(t);
System.out.println("Remaining bal is="+obj1.acctbal);

obj1.showdetail();

JointAccount obj2=  new JointAccount("11-101-23","Amjad","Usman",20000.0);

System.out.println("My Balance is="+obj2.acctbal);
t=obj2.calculatetax();
System.out.println("Tax is ="+t);
obj2.showdetail();
}
}

Answer 1

Several suggestions:

• Account, in its present form, should not be Abstract (you have not defined any method that has only a signature (name and parameters) and no code implementing the method
• You want to have each class protect its internal variables by using only methods to access those values
• You want to use correct syntax for Java (review variable types, syntax, et cetera)
• Follow Java conventions (Class names begin with a capital letter; method names begin with a lowercase letter, ...)

Consider the following replacements

TestApp

public class TestApp {

public static void main(String[] args) {
    SavingAccount sa = new SavingAccount();

    sa.open("Amjad", "5440442378", 1000.00d);

    System.out.println("Account name: " + sa.getName() + ", number: " + sa.getNumber());

    System.out.println("Account balance: " + sa.getBalance());
    System.out.println("Account tax: " + sa.calculate(.05d));
}
}

Account

public class Account {
String name;
String number;
public double balance;

public Account() {
};
public void open(String accountName, String accountNumber, double openingDeposit) {
    name = accountName;
    number = accountNumber;
    balance =  openingDeposit;
}

public void withdraw(double amount) {
    if (balance > amount) {
        balance -= amount;
    }
}
public void deposit(double amount) {
    balance = balance + amount;
}
public String getName() {return name;}
public String getNumber() {return number;}
public double getBalance() {return balance;}
}

SavingAccount (I suspect you wanted "tax" to be "rate", and that you may want to establish the rate of return when you "open" the SavingAccount (i.e. use a variable that is part of the Class)

public class SavingAccount extends Account {

    public double calculate(double rate) {
        return balance * rate;

    }
}

Answer 2

1. string should be String
2. the constructor should be public Account() not public account()

3. accoutTitle(String) is undefined for the type saving_Account : because there is no such this method , you need to define it , and also accountNumber(String)

   class saving_Account extends Account {
    public double calculate(double tax) {
       tax = balance * 0.05;
       return tax;
    }
   
    void accoutTitle(String accountTitle) {
     this.accountTitle=accountTitle;
    }
   
   void accountNumber(String accountNumber) {
     this.accountNumber=accountNumber;
    }
   }
   

Answer 3

You have many problems in your code:

• First, Java is case sensitive, so string should be String, similar for your constructor. Name of the constructor should match exactly with name of your class.

  String accountTitle;
  String accountNumber; //Notice string has been changed to String
  

• Second, you don't have method named accoutTitle, accountNumber

Answer 4

string should have uppercase S. change string to String. String class name starts with 'S'

String accountTitle;
String accountNumber;