Stream Helper Methods in Java
The stream classes provide all of the low-level methods necessary for encoding and decoding Ice types. However, it would be tedious and error-prone to manually encode complex Ice types such as classes, structs, and dictionaries using these low-level functions. For this reason, the Slice compiler optionally generates helper methods for streaming complex Ice types.
We will use the following Slice definitions to demonstrate the language mapping:
module M {
sequence<...> Seq;
dictionary<...> Dict;
struct S {
...
};
enum E { ... };
class C {
...
};
};
The Slice compiler generates the corresponding helper methods shown below:
package M;
public class SeqHelper {
public static T[] read(Ice.InputStream in);
public static void write(Ice.OutputStream out, T[] v);
public static void Ice.OptionalFormat optionalFormat();
}
public class DictHelper {
public static java.util.Map read(Ice.InputStream in);
public static void write(Ice.OutputStream out, java.util.Map<..., ...> v);
public static void Ice.OptionalFormat optionalFormat();
}
public class SHelper {
public static S read(Ice.InputStream in);
public static void write(Ice.OutputStream out, S v);
public static void Ice.OptionalFormat optionalFormat();
}
public class EHelper {
public static E read(Ice.InputStream in);
public static void write(Ice.OutputStream out, E v);
public static void Ice.OptionalFormat optionalFormat();
}
public class CHelper {
public static void read(Ice.InputStream in, CHolder h);
public static void write(Ice.OutputStream out, C v);
public static void Ice.OptionalFormat optionalFormat();
}
public class CPrxHelper {
public static CPrx read(Ice.InputStream in);
public static void write(Ice.OutputStream out, CPrx v);
public static void Ice.OptionalFormat optionalFormat();
}
The optionalFormat method simplifies the task of writing optional values.
The Slice compiler also generates the following methods for struct and enum types:
public class S ... {
...
public void ice_read(Ice.InputStream in);
public void ice_write(Ice.OutputStream out);
};
public class E... {
...
public void ice_read(Ice.InputStream in);
public void ice_write(Ice.OutputStream out);
}
Be aware that a call to CHelper.read does not result in the immediate extraction of an Ice object. The value member of the given CHolder object is updated when readPendingObjects is invoked on the input stream.