Should I set the initial java String values from null to ""?

Often I have a class as such:

public class Foo
{
private String field1;
private String field2;

// etc etc etc
}

This makes the initial values of field1 and field2 equal to null. Would it be better to have all my String class fields as follows?

public class Foo
{
private String field1 = "";
private String field2 = "";

// etc etc etc
}

Then, if I'm consistent with class definition I'd avoid a lot of null pointer problems. What are the problems with this approach?