Well... It is always a nice to have if you place and organize constants at one place. It makes your code maintainable. I guess having a class in a java application holding constants for all the classes is better.
public class MyAppConstants
{
public static final class ModuleOne
{
public static final
String ABC = "some text";
public static final String XYZ = "some other text";
.....................................
.....................................
}
public static final class ModuleTwo
{
public static final String OOO = "XXXXXXXX";
public static final String PPP = "xxxxxxxx";
.........................
.........................
}
............................
............................
}