Can not insert data to instances of own class when declared as an array

I just started learning java and I’m trying to figure out the following requirement. I want to create a instances of my own class as an array. Then I want to refer each object using a loop and enter data. My class is "BankAccount". My instances are "acct[]". But when I try to insert data in to instances I get the following error. Can some one help me to identify the problem.

My code is as follows;

public class BankAccount {

  private String accNo;
  private String name;
  private String type;
  private double balance;

  //Constructor
  public void BankAccount(String accNo, String name, String type, double balance) {
    this.accNo = accNo;
    this.name = name;
    this.type = type;
    this.balance = balance;
  }

  //Diposit
  public void diposit(double amount) {
    balance += amount;
  }

  //Withdraw
  public void withdraw(double amount) {
    if (amount < balance)
      balance -= amount;
    else
      System.out.println("Balnce not enough for the withdrawal");
  }

  //Display data
  public void display() {
    System.out.println("Acc No" + this.accNo);
    System.out.println("Name : " + this.name);
    System.out.println("Type : " + this.balance);
    System.out.println("balance : " + this.balance);
    System.out.println("-------------------------------------------------------------------");
  }
}

public class testBankAccount {

  public static void main(String[] args) {
    //Declaring 10 BankAccount objects as an array
    BankAccount[] acct = new BankAccount[10];

    //inserting data to each object using a loop
    for (int i = 1; i < 11; i++) {
      acct[i].BankAccount("Acc", "name", "type", 0);
      acct[i].diposit(1000);
      acct[i].withdraw(500);
      acct[i].display();
    }
  }
}

>Solution :

You need to create the object, before you can work with it. BankAccount[] acct = new BankAccount[10]; creates the array, it does not create object in every position in the array. You need to create the object before you can invoke its’ methods.

acct[i] = new BankAccount();

Other things to note:

1. public void BankAccount is not a constructor, you have declared a method. Constructor looks like this

public BankAccount(String accNo, String name, String type, double balance) {
  //set fields
}

2. Arrays indexes are zero based, meaning for (int i=1; i<11; i++) will skip first element and throw exception on the last iteration. Correct would be

for (int i=0; i<10; i++) {
 //do stuff
}

3. You really should format your code properly(best to follow java conventions), you will make your own life easier when developing.