ArrayUtils.java

package org.holoeverywhere.util;

import java.lang.reflect.Array;

public class ArrayUtils {
    private static final int CACHE_SIZE = 73;
    private static Object[] EMPTY = new Object[0];
    private static Object[] sCache = new Object[ArrayUtils.CACHE_SIZE];

    @SuppressWarnings("unchecked")
    public static <T> T[] appendElement(Class<T> kind, T[] array, T element) {
        final T[] result;
        final int end;
        if (array != null) {
            end = array.length;
            result = (T[]) Array.newInstance(kind, end + 1);
            System.arraycopy(array, 0, result, 0, end);
        } else {
            end = 0;
            result = (T[]) Array.newInstance(kind, 1);
        }
        result[end] = element;
        return result;
    }

    public static int[] appendInt(int[] cur, int val) {
        if (cur == null) {
            return new int[] {
                    val
            };
        }
        final int N = cur.length;
        for (int i = 0; i < N; i++) {
            if (cur[i] == val) {
                return cur;
            }
        }
        int[] ret = new int[N + 1];
        System.arraycopy(cur, 0, ret, 0, N);
        ret[N] = val;
        return ret;
    }

    public static boolean contains(int[] array, int value) {
        for (int element : array) {
            if (element == value) {
                return true;
            }
        }
        return false;
    }

    public static <T> boolean contains(T[] array, T value) {
        for (T element : array) {
            if (element == null) {
                if (value == null) {
                    return true;
                }
            } else {
                if (value != null && element.equals(value)) {
                    return true;
                }
            }
        }
        return false;
    }

    @SuppressWarnings("unchecked")
    public static <T> T[] emptyArray(Class<T> kind) {
        if (kind == Object.class) {
            return (T[]) ArrayUtils.EMPTY;
        }
        int bucket = (System.identityHashCode(kind) / 8 & 0x7FFFFFFF)
                % ArrayUtils.CACHE_SIZE;
        Object cache = ArrayUtils.sCache[bucket];
        if (cache == null || cache.getClass().getComponentType() != kind) {
            cache = Array.newInstance(kind, 0);
            ArrayUtils.sCache[bucket] = cache;
        }
        return (T[]) cache;
    }

    public static boolean equals(byte[] array1, byte[] array2, int length) {
        if (array1 == array2) {
            return true;
        }
        if (array1 == null || array2 == null || array1.length < length
                || array2.length < length) {
            return false;
        }
        for (int i = 0; i < length; i++) {
            if (array1[i] != array2[i]) {
                return false;
            }
        }
        return true;
    }

    public static int idealBooleanArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need);
    }

    public static int idealByteArraySize(int need) {
        for (int i = 4; i < 32; i++) {
            if (need <= (1 << i) - 12) {
                return (1 << i) - 12;
            }
        }

        return need;
    }

    public static int idealCharArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need * 2) / 2;
    }

    public static int idealFloatArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need * 4) / 4;
    }

    public static int idealIntArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need * 4) / 4;
    }

    public static int idealLongArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need * 8) / 8;
    }

    public static int idealObjectArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need * 4) / 4;
    }

    public static int idealShortArraySize(int need) {
        return ArrayUtils.idealByteArraySize(need * 2) / 2;
    }

    @SuppressWarnings("unchecked")
    public static <T> T[] removeElement(Class<T> kind, T[] array, T element) {
        if (array != null) {
            final int length = array.length;
            for (int i = 0; i < length; i++) {
                if (array[i] == element) {
                    if (length == 1) {
                        return null;
                    }
                    T[] result = (T[]) Array.newInstance(kind, length - 1);
                    System.arraycopy(array, 0, result, 0, i);
                    System.arraycopy(array, i + 1, result, i, length - i - 1);
                    return result;
                }
            }
        }
        return array;
    }

    public static int[] removeInt(int[] cur, int val) {
        if (cur == null) {
            return null;
        }
        final int N = cur.length;
        for (int i = 0; i < N; i++) {
            if (cur[i] == val) {
                int[] ret = new int[N - 1];
                if (i > 0) {
                    System.arraycopy(cur, 0, ret, 0, i);
                }
                if (i < N - 1) {
                    System.arraycopy(cur, i + 1, ret, i, N - i - 1);
                }
                return ret;
            }
        }
        return cur;
    }

    public static long total(long[] array) {
        long total = 0;
        for (long value : array) {
            total += value;
        }
        return total;
    }

    private ArrayUtils() {
    }
}