Comparing strings in Java

Many people who are new to Java have trouble with the meaning of the comparison operator
 ==. The confusion comes from the fact that Java has objects as well as primitive 
 data types. The meaning of == differs for primitives, where it compares values, and 
 for objects, where it compares references instead of values. Objects usually provide a method called
 equals that compares one object with another. Consider these examples 
 for primitive types and for objects.

int foo = 1;
    int hoo = 1;
    System.out.println(foo == hoo); //true - rovno

Integer foo = new Integer(1);
    Integer hoo = new Integer(1);
    System.out.println(foo == hoo); 
    //false - nerovné (porovnáváme dva různé objekty)
    System.out.println(foo.equals(hoo));
    //true - rovno(porovnáváme hodnoty)

The String type is a special case where the distinction above doesn’t quite hold.

String foo = "nazdarbazar";
    String hoo = "nazdarbazar";
    System.out.println(foo == hoo);//true!
    System.out.println(hoo == ("nazdar"+"bazar"));//true!

If that surprises you and you don’t feel like reading the Java Language Specification, where it’s explained nicely in
 3.10.5 String Literals, 
 I recommend the article (Not So) Stupid Questions:String Equality, which 
 explains the issue very well.