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Common, mainly helper classes, featuring finding class of generic parameters, thread testing, version information detection, ArrayHelper, CertificateHelper, StringConverter
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package com.vectorprint;

/*-
 * #%L
 * VectorPrintCommon
 * %%
 * Copyright (C) 2011 - 2018 VectorPrint
 * %%
 * 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.
 * #L%
 */
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.List;
import java.util.stream.IntStream;

/**
 *
 * @author Eduard Drenth at VectorPrint.nl
 */
public class ArrayHelper {

    private ArrayHelper() {
    }

    public static void clear(byte[] bytes) {
        if (bytes == null) {
            return;
        }
        Arrays.fill(bytes, (byte) 0);
    }

    public static void clear(char[] chars) {
        if (chars == null) {
            return;
        }
        Arrays.fill(chars, (char) 0);
    }

    public static float[] unWrap(Float[] fa) {
        if (fa == null) {
            return null;
        }
        float[] rv = new float[fa.length];
        IntStream.range(0,fa.length).forEach(i -> rv[i]= fa[i]);
        return rv;
    }

    public static int[] unWrap(Integer[] ia) {
        if (ia == null) {
            return null;
        }
        return Arrays.stream(ia).mapToInt(Integer::intValue).toArray();
    }

    public static Float[] wrap(float[] fa) {
        if (fa == null) {
            return null;
        }
        return IntStream.range(0, fa.length)
                .mapToObj(i -> fa[i]).toArray(Float[]::new);
    }

    public static Integer[] wrap(int[] ia) {
        if (ia == null) {
            return null;
        }
        return Arrays.stream(ia).boxed().toArray(Integer[]::new);
    }

    public static double[] unWrap(Double[] ia) {
        if (ia == null) {
            return null;
        }
        return Arrays.stream(ia).mapToDouble(Double::doubleValue).toArray();
    }

    public static Double[] wrap(double[] fa) {
        if (fa == null) {
            return null;
        }
        return Arrays.stream(fa).boxed().toArray(Double[]::new);
    }

    public static boolean[] unWrap(Boolean[] ia) {
        if (ia == null) {
            return null;
        }
        boolean[] rv = new boolean[ia.length];
        IntStream.range(0,ia.length).forEach(i -> rv[i]= ia[i]);
        return rv;
    }

    public static Boolean[] wrap(boolean[] fa) {
        if (fa == null) {
            return null;
        }
        return IntStream.range(0, fa.length)
                .mapToObj(i -> fa[i]).toArray(Boolean[]::new);
    }

    public static long[] unWrap(Long[] ia) {
        if (ia == null) {
            return null;
        }
        return Arrays.stream(ia).mapToLong(Long::longValue).toArray();
    }

    public static Long[] wrap(long[] fa) {
        if (fa == null) {
            return null;
        }
        return Arrays.stream(fa).boxed().toArray(Long[]::new);
    }

    public static short[] unWrap(Short[] ia) {
        if (ia == null) {
            return null;
        }
        short[] rv = new short[ia.length];
        IntStream.range(0,ia.length).forEach(i -> rv[i]= ia[i]);
        return rv;
    }

    public static Short[] wrap(short[] fa) {
        if (fa == null) {
            return null;
        }
        return IntStream.range(0, fa.length)
                .mapToObj(i -> fa[i]).toArray(Short[]::new);
    }

    public static char[] unWrap(Character[] ia) {
        if (ia == null) {
            return null;
        }
        char[] rv = new char[ia.length];
        IntStream.range(0,ia.length).forEach(i -> rv[i]= ia[i]);
        return rv;
    }

    public static Character[] wrap(char[] fa) {
        if (fa == null) {
            return null;
        }
        return IntStream.range(0, fa.length)
                .mapToObj(i -> fa[i]).toArray(Character[]::new);
    }

    public static byte[] unWrap(Byte[] ia) {
        if (ia == null) {
            return null;
        }
        byte[] rv = new byte[ia.length];
        IntStream.range(0,ia.length).forEach(i -> rv[i]= ia[i]);
        return rv;
    }

    public static Byte[] wrap(byte[] fa) {
        if (fa == null) {
            return null;
        }
        return IntStream.range(0, fa.length)
                .mapToObj(i -> fa[i]).toArray(Byte[]::new);
    }

    /**
     * convert a List into an array
     *
     * @param 
     * @param l
     * @return an array of type T or null when the List argument is empty
     * @throws NullPointerException when the List argument is null
     */
    public static  T[] toArray(List l) {
        if (!l.isEmpty() && l.get(0) != null) {
            T[] a = (T[]) Array.newInstance(l.get(0).getClass(), l.size());
            return l.toArray(a);
        } else {
            return null;
        }
    }
}