如何仅使用对象的属性获取ArrayList中对象的索引？

Question

This is the ArrayList class, I am trying to get the index of the Account object by using only an Account Number. My Account Object consists of ((object)Customer, (double) Balance) and my Customer Object consists of ((object) Name, (String) actNum, (object) Address) .

import java.util.ArrayList;

public class Database {

    //Instance Veriables
    private ArrayList<Account> list;  
    private Account account;
    private int index;
    private Boolean found;


    public Database()
    {
        list = new ArrayList<Account>();
    }

    public void addAccount(Account a)
    {
        list.add(a);
    }

    public void deleteAccount(int i)
    {
        list.remove(i);
    }

    public void searchAccount(String actNum)
    {

        this.found = list.contains(actNum);
        this.index = list.indexOf(actNum);
        this.account = list.get(0);
    }

    public int getIndex()
    {
        return index;
    }

    public Account getAccount()
    {
        return account;
    }

    public Boolean isInList()
    {
        return found;
    }

}

Answer 1

private int indexForAccountWithNum(String searchActNum) {
    for (int i = 0; i < list.size(); i++)
        if (list.get(i).getCustomer().getAccountNum() == searchActNum)
            return i;
    return -1;
}

Or in Java 8

IntStream.range(0, list.size())
    .filter(i -> list.get(i).getCustomer().getAccountNum() == searchActNum)
    .findFirst().orElse(-1);