Operations on arrays, primitive arrays (like int[]
) and
* primitive wrapper arrays (like Integer[]
).
This class tries to handle null
input gracefully.
* An exception will not be thrown for a null
* array input. However, an Object array that contains a null
* element may throw an exception. Each method documents its behaviour.
-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;
// double IndexOf
//-----------------------------------------------------------------------
/**
* Finds the index of the given value in the array.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
null
* @param valueToFind the value to find
* @return the index of the value within the array,
* {@link #INDEX_NOT_FOUND} (-1
) if not found or null
array input
*/
public static int indexOf(double[] array, double valueToFind) {
return indexOf(array, valueToFind, 0);
}
/**
* Finds the index of the given value within a given tolerance in the array. * This method will return the index of the first value which falls between the region * defined by valueToFind - tolerance and valueToFind + tolerance.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
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} (-1
) if not found or null
array input
*/
public static int indexOf(double[] array, double valueToFind, double tolerance) {
return indexOf(array, valueToFind, 0, tolerance);
}
/**
* Finds the index of the given value in the array starting at the given index.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
A negative startIndex is treated as zero. A startIndex larger than the array
* length will return {@link #INDEX_NOT_FOUND} (-1
).
null
* @param valueToFind the value to find
* @param startIndex the index to start searching at
* @return the index of the value within the array,
* {@link #INDEX_NOT_FOUND} (-1
) if not found or null
array input
*/
public static int indexOf(double[] array, double valueToFind, int startIndex) {
if (isEmpty(array)) {
return INDEX_NOT_FOUND;
}
if (startIndex < 0) {
startIndex = 0;
}
for (int i = startIndex; i < array.length; i++) {
if (valueToFind == array[i]) {
return i;
}
}
return INDEX_NOT_FOUND;
}
/**
* Finds the index of the given value in the array starting at the given index. * This method will return the index of the first value which falls between the region * defined by valueToFind - tolerance and valueToFind + tolerance.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
A negative startIndex is treated as zero. A startIndex larger than the array
* length will return {@link #INDEX_NOT_FOUND} (-1
).
null
* @param valueToFind the value to find
* @param startIndex the index to start searching at
* @param tolerance tolerance of the search
* @return the index of the value within the array,
* {@link #INDEX_NOT_FOUND} (-1
) if not found or null
array input
*/
public static int indexOf(double[] array, double valueToFind, int startIndex, double tolerance) {
if (isEmpty(array)) {
return INDEX_NOT_FOUND;
}
if (startIndex < 0) {
startIndex = 0;
}
double min = valueToFind - tolerance;
double max = valueToFind + tolerance;
for (int i = startIndex; i < array.length; i++) {
if (array[i] >= min && array[i] <= max) {
return i;
}
}
return INDEX_NOT_FOUND;
}
/**
* Finds the last index of the given value within the array.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
null
* @param valueToFind the object to find
* @return the last index of the value within the array,
* {@link #INDEX_NOT_FOUND} (-1
) if not found or null
array input
*/
public static int lastIndexOf(double[] array, double valueToFind) {
return lastIndexOf(array, valueToFind, Integer.MAX_VALUE);
}
/**
* 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.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
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} (-1
) if not found or null
array input
*/
public static int lastIndexOf(double[] array, double valueToFind, double tolerance) {
return lastIndexOf(array, valueToFind, Integer.MAX_VALUE, tolerance);
}
/**
* Finds the last index of the given value in the array starting at the given index.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
A negative startIndex will return {@link #INDEX_NOT_FOUND} (-1
). A startIndex larger than the
* array length will search from the end of the array.
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} (-1
) if not found or null
array input
*/
public static int lastIndexOf(double[] array, double valueToFind, int startIndex) {
if (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;
}
/**
* 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.
* *This method returns {@link #INDEX_NOT_FOUND} (-1
) for a null
input array.
A negative startIndex will return {@link #INDEX_NOT_FOUND} (-1
). A startIndex larger than the
* array length will search from the end of the array.
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} (-1
) if not found or null
array input
*/
public static int lastIndexOf(double[] array, double valueToFind, int startIndex, double tolerance) {
if (isEmpty(array)) {
return INDEX_NOT_FOUND;
}
if (startIndex < 0) {
return INDEX_NOT_FOUND;
} else if (startIndex >= array.length) {
startIndex = array.length - 1;
}
double min = valueToFind - tolerance;
double max = valueToFind + tolerance;
for (int i = startIndex; i >= 0; i--) {
if (array[i] >= min && array[i] <= max) {
return i;
}
}
return INDEX_NOT_FOUND;
}
/**
* Checks if the value is in the given array.
* *The method returns false
if a null
array is passed in.
true
if the array contains the object
*/
public static boolean contains(double[] array, double valueToFind) {
return indexOf(array, valueToFind) != INDEX_NOT_FOUND;
}
/**
* Checks if a value falling within the given tolerance is in the * given array. If the array contains a value within the inclusive range * defined by (value - tolerance) to (value + tolerance).
* *The method returns false
if a null
array
* is passed in.
Checks if an array of primitive doubles is empty or null
.
true
if the array is empty or null
* @since 2.1
*/
public static boolean isEmpty(double[] array) {
if (array == null || array.length == 0) {
return true;
}
return false;
}
}