Java Class New Instance newInstance(final Class clazz)

Description

new Instance

License

Apache License

Declaration

@SuppressWarnings("unchecked")
    public static <T> T newInstance(final Class<T> clazz) 

Method Source Code

//package com.java2s;
/*//from   w  w w. j a  va 2  s.  c o  m
 * Copyright 2002-2008 the original author or authors.
 *
 * 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.ParameterizedType;
import java.lang.reflect.Type;

import java.util.ArrayList;

import java.util.Collection;

import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

public class Main {
    @SuppressWarnings("unchecked")
    public static <T> T newInstance(final Class<T> clazz) {
        if (clazz.isInterface()) {
            // Register Default Implmentation for class,else ioc
            if (Map.class.equals(clazz)) {
                return (T) new LinkedHashMap();
            } else if (List.class.equals(clazz)) {
                return (T) new ArrayList();
            } else if (Set.class.equals(clazz)) {
                return (T) new LinkedHashSet();
            } else if (Collection.class.equals(clazz)) {
                return (T) new ArrayList();
            }
        }
        try {
            return clazz.newInstance();
        } catch (final InstantiationException e) {
            e.printStackTrace();
        } catch (final IllegalAccessException e) {
            e.printStackTrace();
        }
        return null;
    }

    public static Object newInstance(final Type type) {
        final Class<?> clazz = getRawClass(type);
        return newInstance(clazz);
    }

    @SuppressWarnings("unchecked")
    public static <T> Class<T> getRawClass(final Type type) {
        if (type instanceof Class) {
            return (Class<T>) type;
        } else if (type instanceof ParameterizedType) {
            return (Class<T>) ((ParameterizedType) type).getRawType();
        }
        return null;
    }
}

Related

1. newInstance(final Class clazz, final Object[] parameters)
2. newInstance(final Class arrayClass, final int length)
3. newInstance(final Class clazz)
4. newInstance(final Class clazz)
5. newInstance(final Class clazz)
6. newInstance(final Class clazz)
7. newInstance(final Class type, final int length)
8. newInstance(final ClassLoader classLoader, final String className, final Object... constructorArgs)
9. newInstance(final Object obj, final String clazz)