The following chart summarizes the default values for the above data types.
| Data Type | Default Value (for fields) |
| byte | 0 |
| short | 0 |
| int | 0 |
| long | 0L |
| float | 0.0f |
| double | 0.0d |
| char | \'\u0000\' |
| String (or any object) | null |
| boolean | false |
转自：http://java.sun.com/docs/books/tutorial/java/nutsandbolts/datatypes.html