Queries are a key tool for extracting information from monetary amounts. They match the strategy design pattern, allowing different types of query to be easily captured. Examples might be a query that checks if the amount is positive, or one that extracts the currency as a symbol.
There are two equivalent ways of using a MonetaryQuery. The first is
to invoke the method on this interface. The second is to use
MonetaryAmount#query(MonetaryQuery):
// these two lines are equivalent, but the second approach is recommended
monetary = thisQuery.queryFrom(monetary);
// Recommended approach
monetary = monetary.query(thisQuery);
query(MonetaryQuery),
as it is a lot clearer to read in code.
| Modifier and Type | Method and Description |
|---|---|
| public R | Returns: the queried value, may return null to indicate not foundthe monetary amount to query, not null amount)Queries the specified monetary amount. |
| queryFrom | back to summary |
|---|---|
| public R queryFrom(MonetaryAmount amount) Queries the specified monetary amount. This queries the specified monetary amount to return an object using the logic encapsulated in the implementing class. Examples might be a query that checks if the amount is positive, or one that extracts the currency as a symbol.
There are two equivalent ways of using a // these two lines are equivalent, but the second approach is recommended monetary = thisQuery.queryFrom(monetary); monetary = monetary.query(thisQuery);It is recommended to use the second approach, query(MonetaryQuery), as it is a lot clearer to read in code.
Implementation specificationThe implementation must take the input object and query it. The implementation defines the logic of the query and is responsible for documenting that logic. It may use any method onMonetaryAmount
to determine the result. The input object must not be altered.
This method may be called from multiple threads in parallel. It must be thread-safe when invoked.
| |