Question

I got this code:

    System.out.println("Enter the brand and cash value");

    String brand = keyboard.nextLine();

    long cash = keyboard.nextDouble();
    String buffer = keyboard.nextLine();

but even though I enter the exact String value I am trying to compare to, it fails to recognize they are the same. Strangely when I enter this:

compare[0] = new Car ("BMW", 12.00);

instead of this:

compare[0] = new Car (brand, 12.00);

it works

I also use equals:

public boolean equals(Car other)
{
    if (other == null)
    {
        return false;
    }

    if(this.brand == other.brand && this.cash == other.cash)
    {
        return true;
    }
    else
    {
        return false;
    }
}

Answer 1

You are using == to test String equality, and "BMW" is a String literal, which is interned in a pool whereas brand isn’t. In other words, if you have:

String s1 = "BMW";
String s2 = "BMW";
String s3 = getString(); //receives "BMW" from the scanner

s1 == s2 is true
s1 == s3 is false
s2 == s3 is false
s1.equals(s2) is true
s1.equals(s3) is true
s2.equals(s3) is true

Bottom line: you should use equals to compare strings.

You can read more about it in this post.

EDIT

In the code of your equals method you need to change

if(this.brand == other.brand && this.cash == other.cash)

to this:

if(this.brand.equals(other.brand) && this.cash == other.cash)

Also note there are a few other issues with your equals – in particular, it does not override equals: it should be public boolean equals(Object o)

EDIT 2

You could implement your equals method like this for example (it assumes that brand can’t be null – if it is not the case you need to handle that specific case too)

@Override
public boolean equals(Object obj) {
    if (obj == null || getClass() != obj.getClass()) {
        return false;
    }

    final Car other = (Car) obj;
    return (this.cash == other.cash && this.brand.equals(other.brand));
}

Note that you should also override the hashcode method.