Java Mapping for Structures

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Basic Java Mapping for Structures

A Slice structure maps to a Java class with the same name. For each Slice data member, the Java class contains a corresponding public data member. For example, here is our Employee structure once more:

struct Employee
    long number;
    string firstName;
    string lastName;

The Slice-to-Java compiler generates the following definition for this structure:

public final class Employee implements java.lang.Cloneable,
    public long number;
    public String firstName;
    public String lastName;

    public Employee() {}

    public Employee(long number, String firstName, String lastName)
        this.number = number;
        this.firstName = firstName;
        this.lastName = lastName;

    public boolean equals(java.lang.Object rhs)
        // ...
    public int hashCode()
        // ...

    public java.lang.Object clone()
        java.lang.Object o;
            o = super.clone();
        catch(java.lang.CloneNotSupportedException ex)
            assert false; // impossible
        return o;

For each data member in the Slice definition, the Java class contains a corresponding public data member of the same name. Note that you can optionally customize the mapping for data members to use getters and setters instead.

The equals member function compares two structures for equality. Note that the generated class also provides the usual hashCode and clone methods. (clone has the default behavior of making a shallow copy.)

Java Default Constructors for Structures

Structures have a default constructor that initializes data members as follows:

Data Member TypeDefault Value
stringEmpty string
enumFirst enumerator in enumeration
structDefault-constructed value

The constructor won't explicitly initialize a data member if the default Java behavior for that type produces the desired results.

If you wish to ensure that data members of primitive and enumerated types are initialized to specific values, you can declare default values in your Slice definition. The default constructor initializes each of these data members to its declared value instead.

Structures also have a second constructor that has one parameter for each data member. This allows you to construct and initialize an instance in a single statement (instead of first having to construct the instance and then assign to its members).

See Also