Simple java help for if statements [duplicate]

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• How do I compare strings in Java? 23 answers

Can anybody see why this is not working? (answer is string)

System.out.print("Do you have any other costs (yes/no)? :");
answer=keyboard.next();
if (answer=="yes")
{
  System.out.print("How much for miscellaneouos costs? : $");
  costMiscellaneous=keyboard.nextDouble();
}
else
  costMiscellaneous=0;