Finds the last index of the given object within the array. - Android java.lang

Description

Finds the last index of the given object within the array.

Demo Code

/*// w  ww.ja  v a2s. c o m
 * 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.
 */
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Comparator;
import java.util.HashMap;
import java.util.Map;

public class Main{
    /**
     * The index value when an element is not found in a list or array: {@code -1}.
     * This value is returned by methods in this class and can also be used in comparisons with values returned by
     * various method from {@link java.util.List}.
     */
    public static final int INDEX_NOT_FOUND = -1;
    /**
     * <p>Finds the last index of the given object within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param objectToFind  the object to find, may be {@code null}
     * @return the last index of the object within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final Object[] array,
            final Object objectToFind) {
        return lastIndexOf(array, objectToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given object in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than
     * the array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param objectToFind  the object to find, may be {@code null}
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the object within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final Object[] array,
            final Object objectToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        if (objectToFind == null) {
            for (int i = startIndex; i >= 0; i--) {
                if (array[i] == null) {
                    return i;
                }
            }
        } else if (array.getClass().getComponentType()
                .isInstance(objectToFind)) {
            for (int i = startIndex; i >= 0; i--) {
                if (objectToFind.equals(array[i])) {
                    return i;
                }
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final long[] array, final long valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final long[] array,
            final long valueToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final int[] array, final int valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final int[] array, final int valueToFind,
            int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final short[] array,
            final short valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final short[] array,
            final short valueToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     * @since 2.1
     */
    public static int lastIndexOf(final char[] array, final char valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     * @since 2.1
     */
    public static int lastIndexOf(final char[] array,
            final char valueToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final byte[] array, final byte valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final byte[] array,
            final byte valueToFind, int startIndex) {
        if (array == null) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final double[] array,
            final double valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value within a given tolerance in the array.
     * This method will return the index of the last value which falls between the region
     * defined by valueToFind - tolerance and valueToFind + tolerance.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to search through for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param tolerance tolerance of the search
     * @return the index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final double[] array,
            final double valueToFind, final double tolerance) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE, tolerance);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final double[] array,
            final double valueToFind, int startIndex) {
        if (ArrayUtils.isEmpty(array)) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.
     * This method will return the index of the last value which falls between the region
     * defined by valueToFind - tolerance and valueToFind + tolerance.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @param tolerance  search for value within plus/minus this amount
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final double[] array,
            final double valueToFind, int startIndex, final double tolerance) {
        if (ArrayUtils.isEmpty(array)) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        final double min = valueToFind - tolerance;
        final double max = valueToFind + tolerance;
        for (int i = startIndex; i >= 0; i--) {
            if (array[i] >= min && array[i] <= max) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final float[] array,
            final float valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than the
     * array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final float[] array,
            final float valueToFind, int startIndex) {
        if (ArrayUtils.isEmpty(array)) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Finds the last index of the given value within the array.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) if
     * {@code null} array input.</p>
     *
     * @param array  the array to travers backwords looking for the object, may be {@code null}
     * @param valueToFind  the object to find
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final boolean[] array,
            final boolean valueToFind) {
        return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
    }
    /**
     * <p>Finds the last index of the given value in the array starting at the given index.</p>
     *
     * <p>This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.</p>
     *
     * <p>A negative startIndex will return {@link #INDEX_NOT_FOUND} ({@code -1}). A startIndex larger than
     * the array length will search from the end of the array.</p>
     *
     * @param array  the array to traverse for looking for the object, may be {@code null}
     * @param valueToFind  the value to find
     * @param startIndex  the start index to travers backwards from
     * @return the last index of the value within the array,
     *  {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
     */
    public static int lastIndexOf(final boolean[] array,
            final boolean valueToFind, int startIndex) {
        if (ArrayUtils.isEmpty(array)) {
            return INDEX_NOT_FOUND;
        }
        if (startIndex < 0) {
            return INDEX_NOT_FOUND;
        } else if (startIndex >= array.length) {
            startIndex = array.length - 1;
        }
        for (int i = startIndex; i >= 0; i--) {
            if (valueToFind == array[i]) {
                return i;
            }
        }
        return INDEX_NOT_FOUND;
    }
    /**
     * <p>Checks if an array of Objects is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final Object[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive longs is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final long[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive ints is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final int[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive shorts is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final short[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive chars is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final char[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive bytes is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final byte[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive doubles is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final double[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive floats is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final float[] array) {
        return array == null || array.length == 0;
    }
    /**
     * <p>Checks if an array of primitive booleans is empty or {@code null}.</p>
     *
     * @param array  the array to test
     * @return {@code true} if the array is empty or {@code null}
     * @since 2.1
     */
    public static boolean isEmpty(final boolean[] array) {
        return array == null || array.length == 0;
    }
}

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