Difference between the static initializer block and regular static initialization

Question

As the title says, what exactly is the difference between

public static String myString = \"Hello World!\";

and

public stat         


        

Answer 1

To continue with what Scott Stanchfield wrote, you can use the Collections.unmodifiableXXX() methods for safety, though libraries like Google Guava may make that less necessary. Consider:

public static final Map CAPITALS;
static {
    Map map = new HashMap<>(); //Java 7.
    map.put("NY", "Albany");
    map.put("MD", "Annapolis");
    map.put("VA", "Richmond");
    map.put("CT", "Hartford");
    // 46 more states
    CAPITALS = Collections.unmodifiableMap(map);
}

Of course, having a 52-line static block may be disorienting, and so you might instead take the static block and turn it into a static method.

public static final Map CAPITALS = capitals();
private static Map capitals() {
    Map map = new HashMap<>(); //Java 7.
    map.put("NY", "Albany");
    map.put("MD", "Annapolis");
    map.put("VA", "Richmond");
    map.put("CT", "Hartford");
    // 46 more states
    return Collections.unmodifiableMap(map);
}

The difference is a matter of style. You might instead just work with a database table.