Package org.robolectric.util

Class ReflectionHelpers

java.lang.Object
org.robolectric.util.ReflectionHelpers
public class ReflectionHelpers extends Object
Collection of helper methods for calling methods and accessing fields reflectively.

  • Constructor Details

    • ReflectionHelpers

      public ReflectionHelpers()

  • Method Details

    • createNullProxy

      public static <T> T createNullProxy(Class<T> clazz)
      Create a proxy for the given class which returns default values for every method call.

      0 will be returned for any primitive return types, otherwise null will be returned.

      Parameters:
      clazz - the class to provide a proxy instance of.
      Returns:
      a new "Null Proxy" instance of the given class.

    • createDeepProxy

      public static <T> T createDeepProxy(Class<T> clazz)
      Create a proxy for the given class which returns other deep proxies from all it's methods.

      The returned object will be an instance of the given class, but all methods will return either the "default" value for primitives, or another deep proxy for non-primitive types.

      This should be used rarely, for cases where we need to create deep proxies in order not to crash. The inner proxies are impossible to configure, so there is no way to create meaningful behavior from a deep proxy. It serves mainly to prevent Null Pointer Exceptions.

      Parameters:
      clazz - the class to provide a proxy instance of.
      Returns:
      a new "Deep Proxy" instance of the given class.

    • createDelegatingProxy

      public static <T> T createDelegatingProxy(Class<T> clazz, Object delegate)
      Create a proxy for the given class which can delegate method calls to another object.

      If the delegate has no methods whose signature matches, a null (or 0 for primitive types) return value will be returned.

      Parameters:
      clazz - the class to provide a proxy instance of.
      delegate - the object to delegate matching method calls to. A 'matching method' must have exactlu the same method name and parameter class names as the desired method. The @ClassName annotation can be applied to provide a custom class name.
      Returns:
      a new "Delegating Proxy" instance of the given class.

    • defaultsFor

      public static <A extends Annotation> A defaultsFor(Class<A> annotation)

    • getField

      public static <R> R getField(Object object, String fieldName)
      Reflectively get the value of a field.
      Type Parameters:
      R - The return type.
      Parameters:
      object - Target object.
      fieldName - The field name.
      Returns:
      Value of the field on the object.

    • setField

      public static void setField(Object object, String fieldName, Object fieldNewValue)
      Reflectively set the value of a field.
      Parameters:
      object - Target object.
      fieldName - The field name.
      fieldNewValue - New value.

    • setField

      public static void setField(Class<?> type, Object object, String fieldName, Object fieldNewValue)
      Reflectively set the value of a field.
      Parameters:
      type - Target type.
      object - Target object.
      fieldName - The field name.
      fieldNewValue - New value.

    • hasField

      public static boolean hasField(Class<?> clazz, String fieldName)
      Reflectively check if a class has a given field (static or non static).
      Parameters:
      clazz - Target class.
      fieldName - The field name.
      Returns:
      boolean to indicate whether the field exists or not in clazz.

    • getStaticField

      public static <R> R getStaticField(Field field)
      Reflectively get the value of a static field.
      Type Parameters:
      R - The return type.
      Parameters:
      field - Field object.
      Returns:
      Value of the field.

    • getStaticField

      public static <R> R getStaticField(Class<?> clazz, String fieldName)
      Reflectively get the value of a static field.
      Type Parameters:
      R - The return type.
      Parameters:
      clazz - Target class.
      fieldName - The field name.
      Returns:
      Value of the field.

    • setStaticField

      public static void setStaticField(Field field, Object fieldNewValue)
      Reflectively set the value of a static field.
      Parameters:
      field - Field object.
      fieldNewValue - The new value.

    • setStaticField

      public static void setStaticField(Class<?> clazz, String fieldName, Object fieldNewValue)
      Reflectively set the value of a static field.
      Parameters:
      clazz - Target class.
      fieldName - The field name.
      fieldNewValue - The new value.

    • callInstanceMethod

      public static <R> R callInstanceMethod(Object instance, String methodName, ReflectionHelpers.ClassParameter<?>... classParameters)
      Reflectively call an instance method on an object.
      Type Parameters:
      R - The return type.
      Parameters:
      instance - Target object.
      methodName - The method name to call.
      classParameters - Array of parameter types and values.
      Returns:
      The return value of the method.

    • callInstanceMethod

      public static <R> R callInstanceMethod(Class<?> cl, Object instance, String methodName, ReflectionHelpers.ClassParameter<?>... classParameters)
      Reflectively call an instance method on an object on a specific class.
      Type Parameters:
      R - The return type.
      Parameters:
      cl - The class.
      instance - Target object.
      methodName - The method name to call.
      classParameters - Array of parameter types and values.
      Returns:
      The return value of the method.

    • callStaticMethod

      public static <R> R callStaticMethod(ClassLoader classLoader, String fullyQualifiedClassName, String methodName, ReflectionHelpers.ClassParameter<?>... classParameters)
      Helper method for calling a static method using a class from a custom class loader
      Type Parameters:
      R - Return type of the method
      Parameters:
      classLoader - The ClassLoader used to load class
      fullyQualifiedClassName - The full qualified class name with package name of the ClassLoader will load
      methodName - The method name will be called
      classParameters - The input parameters will be used for method calling
      Returns:
      Return the value of the method

    • callStaticMethod

      public static <R> R callStaticMethod(Class<?> clazz, String methodName, ReflectionHelpers.ClassParameter<?>... classParameters)
      Reflectively call a static method on a class.
      Type Parameters:
      R - The return type.
      Parameters:
      clazz - Target class.
      methodName - The method name to call.
      classParameters - Array of parameter types and values.
      Returns:
      The return value of the method.

    • loadClass

      public static Class<?> loadClass(ClassLoader classLoader, String fullyQualifiedClassName)
      Load a class.
      Parameters:
      classLoader - The class loader.
      fullyQualifiedClassName - The fully qualified class name.
      Returns:
      The class object.

    • attemptLoadClass

      public static Optional<Class<?>> attemptLoadClass(ClassLoader classLoader, String fullyQualifiedClassName)
      Attempt to load a class.
      Parameters:
      classLoader - The class loader.
      fullyQualifiedClassName - The fully qualified class name.
      Returns:
      The class object, or null if class is not found.

    • newInstance

      public static <T> T newInstance(Class<T> cl)
      Create a new instance of a class
      Type Parameters:
      T - The class type.
      Parameters:
      cl - The class object.
      Returns:
      New class instance.

    • callConstructor

      public static <R> R callConstructor(Class<? extends R> clazz, ReflectionHelpers.ClassParameter<?>... classParameters)
      Reflectively call the constructor of an object.
      Type Parameters:
      R - The return type.
      Parameters:
      clazz - Target class.
      classParameters - Array of parameter types and values.
      Returns:
      The return value of the method.

    • defaultValueForType

      public static Object defaultValueForType(String returnType)