Copies the specified array, truncating or padding with nulls (if necessary) so the copy has the specified length. - Java Collection Framework

Java examples for Collection Framework:Array Length

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Description

Copies the specified array, truncating or padding with nulls (if necessary) so the copy has the specified length.

Demo Code


//package com.java2s;
import java.lang.reflect.Array;

public class Main {
    /**/* w w w  .j a va  2s .c  om*/
     * Copies the specified array, truncating or padding with nulls (if necessary)
     * so the copy has the specified length.  For all indices that are
     * valid in both the original array and the copy, the two arrays will
     * contain identical values.  For any indices that are valid in the
     * copy but not the original, the copy will contain <tt>null</tt>.
     * Such indices will exist if and only if the specified length
     * is greater than that of the original array.
     * The resulting array is of exactly the same class as the original array.
     *
     * @param original  the array to be copied
     * @param newLength the length of the copy to be returned
     * @return a copy of the original array, truncated or padded with nulls
     * to obtain the specified length
     * @throws NegativeArraySizeException if <tt>newLength</tt> is negative
     * @throws NullPointerException       if <tt>original</tt> is null
     * @since 1.6
     */

    @SuppressWarnings({ "unchecked", "varargs" })
    public static <T> T[] copyOf(T[] original, int newLength) {
        return (T[]) copyOf(original, newLength, original.getClass());
    }

    /**
     * Copies the specified array, truncating or padding with nulls (if necessary)
     * so the copy has the specified length.  For all indices that are
     * valid in both the original array and the copy, the two arrays will
     * contain identical values.  For any indices that are valid in the
     * copy but not the original, the copy will contain <tt>null</tt>.
     * Such indices will exist if and only if the specified length
     * is greater than that of the original array.
     * The resulting array is of the class <tt>newType</tt>.
     *
     * @param original  the array to be copied
     * @param newLength the length of the copy to be returned
     * @param newType   the class of the copy to be returned
     * @return a copy of the original array, truncated or padded with nulls
     * to obtain the specified length
     * @throws NegativeArraySizeException if <tt>newLength</tt> is negative
     * @throws NullPointerException       if <tt>original</tt> is null
     * @throws ArrayStoreException        if an element copied from
     *                                    <tt>original</tt> is not of a runtime type that can be stored in
     *                                    an array of class <tt>newType</tt>
     * @since 1.6
     */

    @SuppressWarnings({ "unchecked", "varargs" })
    public static <T, U> T[] copyOf(U[] original, int newLength,
            Class<? extends T[]> newType) {
        T[] copy = ((Object) newType == (Object) Object[].class) ? (T[]) new Object[newLength]
                : (T[]) Array.newInstance(newType.getComponentType(),
                        newLength);
        System.arraycopy(original, 0, copy, 0,
                Math.min(original.length, newLength));
        return copy;
    }
}

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