org.apache.usergrid.utils.ListUtils.java Source code

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Here is the source code for org.apache.usergrid.utils.ListUtils.java

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/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */
package org.apache.usergrid.utils;

import java.util.ArrayList;
import java.util.Collection;
import java.util.List;
import java.util.UUID;

import org.apache.commons.lang.math.NumberUtils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class ListUtils extends org.apache.commons.collections.ListUtils {
    private static final Logger LOG = LoggerFactory.getLogger(ListUtils.class);

    public static <A> A first(List<A> list) {
        if (list == null) {
            return null;
        }
        if (list.size() == 0) {
            return null;
        }
        return list.get(0);
    }

    public static <A> A last(List<A> list) {
        if (list == null) {
            return null;
        }
        if (list.size() == 0) {
            return null;
        }
        return list.get(list.size() - 1);
    }

    public static <A> Integer firstInteger(List<A> list) {
        A a = first(list);
        if (a == null) {
            return null;
        }

        if (a instanceof Integer) {
            return (Integer) a;
        }

        try {
            return NumberUtils.toInt((String) a);
        } catch (Exception e) {
            LOG.warn("Could not convert list item {} to int", a, e);
        }
        return null;
    }

    public static <A> Long firstLong(List<A> list) {
        A a = first(list);
        if (a == null) {
            return null;
        }

        if (a instanceof Long) {
            return (Long) a;
        }

        try {
            return NumberUtils.toLong((String) a);
        } catch (Exception e) {
            LOG.warn("Could not convert list item {} to long", a, e);
        }
        return null;
    }

    public static <A> Boolean firstBoolean(List<A> list) {
        A a = first(list);
        if (a == null) {
            return null;
        }

        if (a instanceof Boolean) {
            return (Boolean) a;
        }

        try {
            return Boolean.parseBoolean((String) a);
        } catch (Exception e) {
            LOG.warn("Could not convert list item {} to boolean", a, e);
        }
        return null;
    }

    public static <A> UUID firstUuid(List<A> list) {
        A i = first(list);
        if (i == null) {
            return null;
        }

        if (i instanceof UUID) {
            return (UUID) i;
        }

        try {
            return UUIDUtils.tryGetUUID((String) i);
        } catch (Exception e) {
            LOG.warn("Could not convert list item {} to UUID", i, e);
        }
        return null;
    }

    public static boolean isEmpty(List<?> list) {
        return (list == null) || (list.size() == 0);
    }

    public static <T> List<T> dequeueCopy(List<T> list) {
        if (!isEmpty(list)) {
            list = list.subList(1, list.size());
        }
        return list;
    }

    public static <T> List<T> initCopy(List<T> list) {
        if (!isEmpty(list)) {
            list = new ArrayList<T>(list);
        } else {
            list = new ArrayList<T>();
        }
        return list;
    }

    public static <T> T dequeue(List<T> list) {
        if (!isEmpty(list)) {
            return list.remove(0);
        }
        return null;
    }

    public static <T> List<T> queue(List<T> list, T item) {
        if (list == null) {
            list = new ArrayList<T>();
        }
        list.add(item);
        return list;
    }

    public static <T> List<T> requeue(List<T> list, T item) {
        if (list == null) {
            list = new ArrayList<T>();
        }
        list.add(0, item);
        return list;
    }

    @SuppressWarnings({ "unchecked", "rawtypes" })
    public static List<?> flatten(Collection<?> l) {
        boolean hasCollection = false;
        for (Object o : l) {
            if (o instanceof Collection) {
                hasCollection = true;
                break;
            }
        }
        if (!hasCollection && (l instanceof List)) {
            return (List<?>) l;
        }
        List newList = new ArrayList();
        for (Object o : l) {
            if (o instanceof List) {
                newList.addAll(flatten((List) o));
            } else {
                newList.add(o);
            }
        }
        return newList;
    }

    public static boolean anyNull(List<?> l) {
        for (Object o : l) {
            if (o == null) {
                return true;
            }
        }
        return false;
    }

    public static boolean anyNull(Object... objects) {
        for (Object o : objects) {
            if (o == null) {
                return true;
            }
        }
        return false;
    }
}