我无法弄清楚此错误消息（ArrayList BankAccount代码）

Question

I'm trying to practice for my test in Java tomorrow, but I can't figure out what is going on.

import java.util.ArrayList;
public class BankAccount
{
    public static void BankAccount(double x)
    {
        ArrayList<BankAccount> accounts = new ArrayList<BankAccount>();
        BankAccount ted = new BankAccount(400);
        BankAcconut bob = new BankAccount(300);
        BackAccount carol = new BankAccount(500);
        accounts.add(new BankAccount(300));
    }
}

I keep getting an error message that says "constructor BankAccount in class BankAccount cannot be applied to given terms; required: no arguments; found:int;

I know this is small cheese compared to what you guys are doing, but I'm new to this. Thanks in advance.

Answer 1

You haven't supplied any constructors, so Java creates a default constructor , with no arguments, that does nothing.

Supply a one-argument constructor that takes an int that you are supplying.

Answer 2

You don't have any explicit constructor for BankAccount . You appear to be confusing your static method called BankAccount (don't do that; it's asking to get confused) with a constructor. You probably mean to do something like this:

public class BankAccount {
    private double balance;

    public BankAccount(double balance) {
        this.balance = balance;
    }
}

Then put that other code that's constructing BankAccount objects somewhere else, like main . (It's okay to put main on this same class, but it's essentially irrelevant where it goes. What matters is that you need a constructor for the class you're trying to construct.)

Answer 3

Your class BankAccount needs a constructor that looks like this.

public BankAccount(int funds){
    this.funds = funds;
}

This assumes that class BankAccount has an attribute called funds , which could represent, for example, the available funds.

Answer 4

public static void BankAccount(double x)

There are no static constructors in Java. Thats why it doesn't get regocnized as a constructor. Just delete the static and the void as pointed out below.

Because there is no constructor defined automatically a constructor is added on compile time that has no arguments and because "your" constructor does not match the constructor you want to call you get this error.

Answer 5

This happens because you have not defined BankAccount constructor that accepts an int . Modify your code as follows:

import java.util.ArrayList;
public class BankAccount
{
    // public constructor of BankAccount class
    public BankAccount(int value){
        // do something here with value
    }
    public static void BankAccount(double x)
    {
        ArrayList<BankAccount> accounts = new ArrayList<BankAccount>();
        BankAccount ted = new BankAccount(400);
        BankAcconut bob = new BankAccount(300);
        BackAccount carol = new BankAccount(500);
        accounts.add(new BankAccount(300));
    }
}

Answer 6

import java.util.ArrayList;


public class BankAccount {

private double balance = 0.0;

public BankAccount() {
    // TODO Auto-generated constructor stub

}

public BankAccount(double d) {
    // TODO Auto-generated constructor stub
    balance = d;
}

public static void main(String[] args) //BankAccount(double x)
{
    ArrayList<BankAccount> accounts = new ArrayList<BankAccount>();
    BankAccount ted = new BankAccount(400.0);
    BankAccount bob = new BankAccount(300.0);
    BankAccount carol = new BankAccount(500);
    accounts.add(new BankAccount(300));
}

}

Answer 7

Add "D" after the numbers; This will make make it a double.

So this

BankAccount ted = new BankAccount(400);

becomes

BankAccount ted = new BankAccount(400D);