Contains Same Method Signature : Method « Reflection « Java Tutorial

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Java Tutorial » Reflection » Method 
7.5.28.Contains Same Method SignaturePrevious/Next
//
//$Id: IntrospectionUtil.java 1540 2007-01-19 12:24:10Z janb $
//Copyright 2006 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at 
//http://www.apache.org/licenses/LICENSE-2.0
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.
//

import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Arrays;
import java.util.List;

public class IntrospectionUtil {

  public static boolean containsSameMethodSignature(Method method, Class c, boolean checkPackage) {
    if (checkPackage) {
      if (!c.getPackage().equals(method.getDeclaringClass().getPackage()))
        return false;
    }

    boolean samesig = false;
    Method[] methods = c.getDeclaredMethods();
    for (int i = 0; i < methods.length && !samesig; i++) {
      if (IntrospectionUtil.isSameSignature(method, methods[i]))
        samesig = true;
    }
    return samesig;
  }

  public static boolean containsSameFieldName(Field field, Class c, boolean checkPackage) {
    if (checkPackage) {
      if (!c.getPackage().equals(field.getDeclaringClass().getPackage()))
        return false;
    }

    boolean sameName = false;
    Field[] fields = c.getDeclaredFields();
    for (int i = 0; i < fields.length && !sameName; i++) {
      if (fields[i].getName().equals(field.getName()))
        sameName = true;
    }
    return sameName;
  }


  public static boolean isInheritable(Package pack, Member member) {
    if (pack == null)
      return false;
    if (member == null)
      return false;

    int modifiers = member.getModifiers();
    if (Modifier.isPublic(modifiers))
      return true;
    if (Modifier.isProtected(modifiers))
      return true;
    if (!Modifier.isPrivate(modifiers&& pack.equals(member.getDeclaringClass().getPackage()))
      return true;

    return false;
  }

  public static boolean checkParams(Class[] formalParams, Class[] actualParams, boolean strict) {
    if (formalParams == null && actualParams == null)
      return true;
    if (formalParams == null && actualParams != null)
      return false;
    if (formalParams != null && actualParams == null)
      return false;

    if (formalParams.length != actualParams.length)
      return false;

    if (formalParams.length == 0)
      return true;

    int j = 0;
    if (strict) {
      while (j < formalParams.length && formalParams[j].equals(actualParams[j]))
        j++;
    else {
      while ((j < formalParams.length&& (formalParams[j].isAssignableFrom(actualParams[j]))) {
        j++;
      }
    }

    if (j != formalParams.length) {
      return false;
    }

    return true;
  }

  public static boolean isSameSignature(Method methodA, Method methodB) {
    if (methodA == null)
      return false;
    if (methodB == null)
      return false;

    List parameterTypesA = Arrays.asList(methodA.getParameterTypes());
    List parameterTypesB = Arrays.asList(methodB.getParameterTypes());

    if (methodA.getName().equals(methodB.getName()) && parameterTypesA.containsAll(parameterTypesB))
      return true;

    return false;
  }

  public static boolean isTypeCompatible(Class formalType, Class actualType, boolean strict) {
    if (formalType == null && actualType != null)
      return false;
    if (formalType != null && actualType == null)
      return false;
    if (formalType == null && actualType == null)
      return true;

    if (strict)
      return formalType.equals(actualType);
    else
      return formalType.isAssignableFrom(actualType);
  }


  protected static Method findInheritedMethod(Package pack, Class clazz, String methodName,
      Class[] args, boolean strictArgsthrows NoSuchMethodException {
    if (clazz == null)
      throw new NoSuchMethodException("No class");
    if (methodName == null)
      throw new NoSuchMethodException("No method name");

    Method method = null;
    Method[] methods = clazz.getDeclaredMethods();
    for (int i = 0; i < methods.length && method == null; i++) {
      if (methods[i].getName().equals(methodName&& isInheritable(pack, methods[i])
          && checkParams(methods[i].getParameterTypes(), args, strictArgs))
        method = methods[i];
    }
    if (method != null) {
      return method;
    else
      return findInheritedMethod(clazz.getPackage(), clazz.getSuperclass(), methodName, args,
          strictArgs);
  }

  protected static Field findInheritedField(Package pack, Class clazz, String fieldName,
      Class fieldType, boolean strictTypethrows NoSuchFieldException {
    if (clazz == null)
      throw new NoSuchFieldException("No class");
    if (fieldName == null)
      throw new NoSuchFieldException("No field name");
    try {
      Field field = clazz.getDeclaredField(fieldName);
      if (isInheritable(pack, field&& isTypeCompatible(fieldType, field.getType(), strictType))
        return field;
      else
        return findInheritedField(clazz.getPackage(), clazz.getSuperclass(), fieldName, fieldType,
            strictType);
    catch (NoSuchFieldException e) {
      return findInheritedField(clazz.getPackage(), clazz.getSuperclass(), fieldName, fieldType,
          strictType);
    }
  }

}
7.5.Method
7.5.1.List methods of a class using Reflection
7.5.2.Design your own class loader
7.5.3.Get method my parameters
7.5.4.Show public methods.
7.5.5.Method Inspector
7.5.6.Invoke methods of an object using reflection
7.5.7.Call a member function to get the value
7.5.8.Prints out the declared methods on java.lang.Number
7.5.9.Demonstrates how to get simple method information
7.5.10.Prints out the declared methods on java.lang.Object
7.5.11.Demonstrates how to get specific method information
7.5.12.Get the current method name
7.5.13.Get the current method name With JDK1.5
7.5.14.Get method from a class by name
7.5.15.Get super class and all its declared methods
7.5.16.Invoke a method with parameter
7.5.17.Call a class method with 2 arguments
7.5.18.Call all possible exceptions during method invocation with reflection
7.5.19.get Declared Method by name and parameter type
7.5.20.Getting the Methods of a Class Object: By obtaining a list of all declared methods
7.5.21.Getting the Methods of a Class Object: By obtaining a list of all public methods, both declared and inherited.
7.5.22.Getting the Methods of a Class Object: By obtaining a particular Method object.
7.5.23.Invoke method with wrong parameters
7.5.24.Checks whether the specified class contains a method matching the specified name.
7.5.25.Find method
7.5.26.Returns method with the specified name
7.5.27.Sorts methods according to their name, number of parameters, and parameter types.
7.5.28.Contains Same Method Signature
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