Guava tips: Defaults and HttpHeaders

We’ll cover two tiny Guava classes today, which I’m sure will provoke a “ehm… nice to know, I guess?” from you! :-)

Defaults

The simple Defaults class has only one method: defaultValue, which returns the “default value” given a Class:

• for the primitives numeric data types (char, short, int, long, float, double) it will return 0;
• for boolean it will return false;
• for byte it will return (byte)0;
• and for objects it will return null.

For example:

assertEquals(Long.valueOf(0L), Defaults.defaultValue(long.class));
assertEquals(false, Defaults.defaultValue(boolean.class));
assertEquals(null, Defaults.defaultValue(String.class));

HttpHeaders

The tiny class HttpHeaders simply contains one constant for each of the standard HTTP headers. Nothing more, nothing less. It’s better than rolling the constant in your code, I suppose.