Java Class New Instance newInstance(final ClassLoader classLoader, final String className, final Object... constructorArgs)

Description

new Instance

License

Apache License

Declaration

@SuppressWarnings("unchecked")
    public static <T> T newInstance(final ClassLoader classLoader, final String className,
            final Object... constructorArgs) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import java.util.Arrays;

public class Main {
    @SuppressWarnings("unchecked")
    public static <T> T newInstance(final ClassLoader classLoader, final String className,
            final Object... constructorArgs) {
        try {//from   ww w .  java2  s  . co  m
            return (T) newInstance(Class.forName(className, true, classLoader), constructorArgs);
        } catch (final ClassNotFoundException e) {
            e.printStackTrace();
        }
        return null;
    }

    @SuppressWarnings("unchecked")
    public static <T> T newInstance(final String className, final Object... constructorArgs) {
        try {
            return (T) newInstance(Class.forName(className), constructorArgs);
        } catch (final ClassNotFoundException e) {
            //         e.printStackTrace();
        }
        return null;
    }

    public static <T> T newInstance(final Class<T> clazz, final Object... constructorArgs) {
        final Constructor<T> constructor = getConstructor(clazz, constructorArgs);
        if (constructor != null) {
            try {
                return constructor.newInstance(constructorArgs);
            } catch (final InstantiationException e) {
                e.printStackTrace();
            } catch (final IllegalAccessException e) {
                e.printStackTrace();
            } catch (final IllegalArgumentException e) {
                e.printStackTrace();
            } catch (final InvocationTargetException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    public static <T> Constructor<T> getConstructor(final Class<T> clazz, final Object... constructorArgs) {
        final Constructor<T> constructor = getStrictConstructor(clazz, constructorArgs);
        return constructor == null ? findCompatibleConstructor(clazz, constructorArgs) : constructor;
    }

    public static <T> Constructor<T> getStrictConstructor(final Class<T> clazz, final Object... constructorArgs) {
        final Class<?>[] argsTypes = objsToClasses(constructorArgs);
        try {
            return clazz.getConstructor(argsTypes);
        } catch (final NoSuchMethodException e) {
            e.printStackTrace();
        } catch (final SecurityException e) {
            e.printStackTrace();
        }
        return null;
    }

    public static <T> Constructor<T> findCompatibleConstructor(final Class<T> clazz,
            final Object... constructorArgs) {
        @SuppressWarnings("unchecked")
        final Constructor<T>[] constructors = (Constructor<T>[]) clazz.getConstructors();
        final Class<?>[] argsTypes = objsToClasses(constructorArgs);
        Constructor<T> c = null;
        for (final Constructor<T> constructor : constructors) {
            final Class<?>[] parametersTypes = constructor.getParameterTypes();
            if (parametersTypes.length == argsTypes.length) {
                if (Arrays.equals(parametersTypes, argsTypes)) {
                    return constructor;
                }
                if (checkAllAssignable(parametersTypes, constructorArgs)) {
                    c = constructor;
                }
            }
        }
        return c;
    }

    public static Class<?>[] objsToClasses(final Object... objs) {
        final Class<?>[] types = new Class<?>[objs.length];
        int index = 0;
        for (final Object o : objs) {
            types[index] = o.getClass();
            ++index;
        }
        return types;
    }

    public static boolean checkAllAssignable(final Class<?>[] superClasses, final Class<?>... subClasses) {
        if (superClasses.length != subClasses.length) {
            return false;
        }
        int index = 0;
        for (final Class<?> c : superClasses) {
            if (!c.isAssignableFrom(subClasses[index])) {
                return false;
            }
            ++index;
        }
        return true;
    }

    public static boolean checkAllAssignable(final Class<?>[] superClasses, final Object... objects) {
        return checkAllAssignable(superClasses, objsToClasses(objects));
    }
}

Related

1. newInstance(final Class clazz)
2. newInstance(final Class clazz)
3. newInstance(final Class clazz)
4. newInstance(final Class clazz)
5. newInstance(final Class type, final int length)
6. newInstance(final Object obj, final String clazz)
7. newInstance(final String className, ClassLoader cl)
8. newInstance(final String className, final Object[] args)
9. newInstance(final String fullyQualifiedClass)