com.google.gwt.core.ext.typeinfo

## Class TypeOracle

- java.lang.Object
- - com.google.gwt.core.ext.typeinfo.TypeOracle

    public abstract class TypeOracle
    extends java.lang.Object

Provides type-related information about a set of source files.

All type objects exposed, such as `JClassType` and others, have a stable identity relative to this type oracle instance. Consequently, you can reliably compare object identity of any objects this type oracle produces. For example, the following code relies on this stable identity guarantee:

     JClassType o = typeOracle.getJavaLangObject();
     JClassType s1 = typeOracle.getType("java.lang.String");
     JClassType s2 = typeOracle.getType("java.lang.String");
     assert (s1 == s2);
     assert (o == s1.getSuperclass());
     JParameterizedType ls = typeOracle.parse("java.util.List<java.lang.String>");
     assert (ls.getTypeArgs()[0] == s1);

### Constructor Summary

Constructors
Constructor and Description
`TypeOracle()`

### Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
`abstract JPackage` `findPackage(java.lang.String pkgName)` Attempts to find a package by name.
`abstract JClassType` `findType(java.lang.String name)` Finds a class or interface given its fully-qualified name.
`abstract JClassType` `findType(java.lang.String pkgName, java.lang.String typeName)` Finds a type given its package-relative name.
`abstract JArrayType` `getArrayType(JType componentType)` Gets the type object that represents an array of the specified type.
`abstract JClassType` `getJavaLangObject()` Gets a reference to the type object representing `java.lang.Object`.
`abstract JPackage` `getOrCreatePackage(java.lang.String name)` Ensure that a package with the specified name exists as well as its parent packages.
`abstract JPackage` `getPackage(java.lang.String pkgName)` Gets a package by name.
`abstract JPackage[]` `getPackages()` Gets an array of all packages known to this type oracle.
`abstract JParameterizedType` `getParameterizedType(JGenericType genericType, JClassType[] typeArgs)` Gets the parameterized type object that represents the combination of a specified raw type and a set of type arguments.
`abstract JParameterizedType` `getParameterizedType(JGenericType genericType, JClassType enclosingType, JClassType[] typeArgs)` Gets the parameterized type object that represents the combination of a specified raw type and a set of type arguments.
`abstract JClassType` `getSingleJsoImpl(JClassType intf)` Returns the single implementation type for an interface returned via `getSingleJsoImplInterfaces()` or `null` if no JSO implementation is defined.
`abstract java.util.Set<? extends JClassType>` `getSingleJsoImplInterfaces()` Returns an unmodifiable, live view of all interface types that are implemented by exactly one JSO subtype.
`abstract JClassType` `getType(java.lang.String name)` Finds a type given its fully qualified name.
`abstract JClassType` `getType(java.lang.String pkgName, java.lang.String topLevelTypeSimpleName)` Finds a type given its package-relative name.
`abstract JClassType[]` `getTypes()` Gets all types, both top-level and nested.
`abstract JWildcardType` `getWildcardType(JWildcardType.BoundType boundType, JClassType typeBound)`
`abstract JType` `parse(java.lang.String type)` Parses the string form of a type to produce the corresponding type object.
`static void` `sort(JClassType[] types)` Convenience method to sort class types in a consistent way.
`static void` `sort(JConstructor[] ctors)` Convenience method to sort constructors in a consistent way.
`static void` `sort(JField[] fields)` Convenience method to sort fields in a consistent way.
`static void` `sort(JMethod[] methods)` Convenience method to sort methods in a consistent way.

### Methods inherited from class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

### Constructor Detail

#### TypeOracle

    public TypeOracle()

### Method Detail

#### sort

    public static void sort(JClassType[] types)

Convenience method to sort class types in a consistent way. Note that the order is subject to change and is intended to generate an "aesthetically pleasing" order rather than a computationally reliable order.

#### sort

    public static void sort(JConstructor[] ctors)

Convenience method to sort constructors in a consistent way. Note that the order is subject to change and is intended to generate an "aesthetically pleasing" order rather than a computationally reliable order.

#### sort

    public static void sort(JField[] fields)

Convenience method to sort fields in a consistent way. Note that the order is subject to change and is intended to generate an "aesthetically pleasing" order rather than a computationally reliable order.

#### sort

    public static void sort(JMethod[] methods)

Convenience method to sort methods in a consistent way. Note that the order is subject to change and is intended to generate an "aesthetically pleasing" order rather than a computationally reliable order.

#### findPackage

    public abstract JPackage findPackage(java.lang.String pkgName)

Attempts to find a package by name. All requests for the same package return the same package object.

Returns:
  `null` if the package could not be found

#### findType

    public abstract JClassType findType(java.lang.String name)

Finds a class or interface given its fully-qualified name.

Parameters:
  `name` - fully-qualified class/interface name - for nested classes, use its source name rather than its binary name (that is, use a "." rather than a "$")
Returns:
  `null` if the type is not found

#### findType

    public abstract JClassType findType(java.lang.String pkgName,
                                        java.lang.String typeName)

Finds a type given its package-relative name. For nested classes, use its source name rather than its binary name (that is, use a "." rather than a "$").

Returns:
  `null` if the type is not found

#### getArrayType

    public abstract JArrayType getArrayType(JType componentType)

Gets the type object that represents an array of the specified type. The returned type always has a stable identity so as to guarantee that all calls to this method with the same argument return the same object.

Parameters:
  `componentType` - the component type of the array, which can itself be an array type
Returns:
  a type object representing an array of the component type

#### getJavaLangObject

    public abstract JClassType getJavaLangObject()

Gets a reference to the type object representing `java.lang.Object`.

#### getOrCreatePackage

    public abstract JPackage getOrCreatePackage(java.lang.String name)

Ensure that a package with the specified name exists as well as its parent packages.

#### getPackage

    public abstract JPackage getPackage(java.lang.String pkgName)
                                 throws NotFoundException

Gets a package by name. All requests for the same package return the same package object.

Returns:
  the package object associated with the specified name
Throws:
  `NotFoundException` - if `getOrCreatePackage` hasn't been called for this package or any child packages

#### getPackages

    public abstract JPackage[] getPackages()

Gets an array of all packages known to this type oracle.

Returns:
  an array of packages, possibly of zero-length

#### getParameterizedType

    public abstract JParameterizedType getParameterizedType(JGenericType genericType,
                                                            JClassType enclosingType,
                                                            JClassType[] typeArgs)

Gets the parameterized type object that represents the combination of a specified raw type and a set of type arguments. The returned type always has a stable identity so as to guarantee that all calls to this method with the same arguments return the same object.

Parameters:
  `genericType` - a generic base class
  `enclosingType` -
  `typeArgs` - the type arguments bound to the specified generic type
Returns:
  a type object representing this particular binding of type arguments to the specified generic
Throws:
  `java.lang.IllegalArgumentException` - if the parameterization of a non-static member type does not specify an enclosing type or if not enough arguments were specified to parameterize the generic type
  `java.lang.NullPointerException` - if genericType is `null`

#### getParameterizedType

    public abstract JParameterizedType getParameterizedType(JGenericType genericType,
                                                            JClassType[] typeArgs)

Gets the parameterized type object that represents the combination of a specified raw type and a set of type arguments. The returned type always has a stable identity so as to guarantee that all calls to this method with the same arguments return the same object.

Parameters:
  `genericType` - a generic base class
  `typeArgs` - the type arguments bound to the specified generic type
Returns:
  a type object representing this particular binding of type arguments to the specified generic
Throws:
  `java.lang.IllegalArgumentException` - if the generic type is a non-static member type or if not enough arguments were specified to parameterize the generic type
  `java.lang.NullPointerException` - if genericType is `null`

#### getSingleJsoImpl

    public abstract JClassType getSingleJsoImpl(JClassType intf)

Returns the single implementation type for an interface returned via `getSingleJsoImplInterfaces()` or `null` if no JSO implementation is defined.

#### getSingleJsoImplInterfaces

    public abstract java.util.Set<? extends JClassType> getSingleJsoImplInterfaces()

Returns an unmodifiable, live view of all interface types that are implemented by exactly one JSO subtype.

#### getType

    public abstract JClassType getType(java.lang.String name)
                                throws NotFoundException

Finds a type given its fully qualified name. For nested classes, use its source name rather than its binary name (that is, use a "." rather than a "$").

Returns:
  the specified type
Throws:
  `NotFoundException`

#### getType

    public abstract JClassType getType(java.lang.String pkgName,
                                       java.lang.String topLevelTypeSimpleName)
                                throws NotFoundException

Finds a type given its package-relative name. For nested classes, use its source name rather than its binary name (that is, use a "." rather than a "$").

Returns:
  the specified type
Throws:
  `NotFoundException`

#### getTypes

    public abstract JClassType[] getTypes()

Gets all types, both top-level and nested.

Returns:
  an array of types, possibly of zero length

#### getWildcardType

    public abstract JWildcardType getWildcardType(JWildcardType.BoundType boundType,
                                                  JClassType typeBound)

#### parse

    public abstract JType parse(java.lang.String type)
                         throws TypeOracleException

Parses the string form of a type to produce the corresponding type object. The types that can be parsed include primitives, class and interface names, simple parameterized types (those without wildcards or bounds), and arrays of the preceding.

Examples of types that can be parsed by this method.

- `int`
- `java.lang.Object`
- `java.lang.String[]`
- `char[][]`
- `void`
- `List<Shape>`
- `List<List<Shape>>`

Parameters:
  `type` - a type signature to be parsed
Returns:
  the type object corresponding to the parse type
Throws:
  `TypeOracleException`