Thread: Compiler refuses to "accept" my string variable - need help

package input;

import java.util.Scanner;

public class Input {

/**
* Created by Björn Johansson 2012
*/

public static void main(String[] args)
{

Scanner user_input = new Scanner(System.in);

String first_name;
System.out.print("Vad heter du i förnamn? ");
first_name = user_input.next();

if (first_name = "Ola")
{
System.out.print("Hej Ola!");
}

else if (first_name = "Eva")
{
System.out.print("Hej Eva!");
}

else
{
System.out.print("Du har angett ett ogiltigt namn!");
}


}

}


Exception in thread "main" java.lang.Error: Unresolved compilation problems:
Type mismatch: cannot convert from String to boolean
Type mismatch: cannot convert from String to boolean

at input.Input.main(Input.java:20)

I replaced

first_name =

with

first_name ==

now the program compiles and runs without problems! But when I enter the name Eva as a name, I get as a result ogiltigt namn! (that is disqualified name in english) but it should return the text: Hej Eva!

So how do I fix that?

I was reading over at java-samples.com for some examples of how to do this, but I must admit that since I'm a total newbie on java, I'm not sure what I'm doing at times, so can you give me a hint on how I should do that in source code?