Array (Java Platform SE 8 )
Keywords: java.lang.reflect.Array class
Date: 2017-01-22

compact1, compact2, compact3
java.lang.reflect

## Class Array

- java.lang.Object
- - java.lang.reflect.Array

-     public final class Array
      extends Object

  The `Array` class provides static methods to dynamically create and access Java arrays.

  `Array` permits widening conversions to occur during a get or set operation, but throws an `IllegalArgumentException` if a narrowing conversion would occur.

- - ### Method Summary

    All Methods Static Methods Concrete Methods
    Modifier and Type | Method and Description
    --- | ---
    `static Object` | `get(Object array, int index)` Returns the value of the indexed component in the specified array object.
    `static boolean` | `getBoolean(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `boolean`.
    `static byte` | `getByte(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `byte`.
    `static char` | `getChar(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `char`.
    `static double` | `getDouble(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `double`.
    `static float` | `getFloat(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `float`.
    `static int` | `getInt(Object array, int index)` Returns the value of the indexed component in the specified array object, as an `int`.
    `static int` | `getLength(Object array)` Returns the length of the specified array object, as an `int`.
    `static long` | `getLong(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `long`.
    `static short` | `getShort(Object array, int index)` Returns the value of the indexed component in the specified array object, as a `short`.
    `static Object` | `newInstance(Class<?> componentType, int... dimensions)` Creates a new array with the specified component type and dimensions.
    `static Object` | `newInstance(Class<?> componentType, int length)` Creates a new array with the specified component type and length.
    `static void` | `set(Object array, int index, Object value)` Sets the value of the indexed component of the specified array object to the specified new value.
    `static void` | `setBoolean(Object array, int index, boolean z)` Sets the value of the indexed component of the specified array object to the specified `boolean` value.
    `static void` | `setByte(Object array, int index, byte b)` Sets the value of the indexed component of the specified array object to the specified `byte` value.
    `static void` | `setChar(Object array, int index, char c)` Sets the value of the indexed component of the specified array object to the specified `char` value.
    `static void` | `setDouble(Object array, int index, double d)` Sets the value of the indexed component of the specified array object to the specified `double` value.
    `static void` | `setFloat(Object array, int index, float f)` Sets the value of the indexed component of the specified array object to the specified `float` value.
    `static void` | `setInt(Object array, int index, int i)` Sets the value of the indexed component of the specified array object to the specified `int` value.
    `static void` | `setLong(Object array, int index, long l)` Sets the value of the indexed component of the specified array object to the specified `long` value.
    `static void` | `setShort(Object array, int index, short s)` Sets the value of the indexed component of the specified array object to the specified `short` value.

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Method Detail

    - #### newInstance

          public static Object newInstance(Class<?> componentType,
                                           int length)
                                    throws NegativeArraySizeException

      Creates a new array with the specified component type and length. Invoking this method is equivalent to creating an array as follows:

      >      int[] x = {length};
      >      Array.newInstance(componentType, x);

      The number of dimensions of the new array must not exceed 255.

      Parameters:
        `componentType` - the `Class` object representing the component type of the new array
        `length` - the length of the new array
      Returns:
        the new array
      Throws:
        `NullPointerException` - if the specified `componentType` parameter is null
        `IllegalArgumentException` - if componentType is `Void.TYPE` or if the number of dimensions of the requested array instance exceed 255.
        `NegativeArraySizeException` - if the specified `length` is negative

    - #### newInstance

          public static Object newInstance(Class<?> componentType,
                                           int... dimensions)
                                    throws IllegalArgumentException,
                                           NegativeArraySizeException

      Creates a new array with the specified component type and dimensions. If `componentType` represents a non-array class or interface, the new array has `dimensions.length` dimensions and `componentType` as its component type. If `componentType` represents an array class, the number of dimensions of the new array is equal to the sum of `dimensions.length` and the number of dimensions of `componentType`. In this case, the component type of the new array is the component type of `componentType`.

      The number of dimensions of the new array must not exceed 255.

      Parameters:
        `componentType` - the `Class` object representing the component type of the new array
        `dimensions` - an array of `int` representing the dimensions of the new array
      Returns:
        the new array
      Throws:
        `NullPointerException` - if the specified `componentType` argument is null
        `IllegalArgumentException` - if the specified `dimensions` argument is a zero-dimensional array, if componentType is `Void.TYPE`, or if the number of dimensions of the requested array instance exceed 255.
        `NegativeArraySizeException` - if any of the components in the specified `dimensions` argument is negative.

    - #### getLength

          public static int getLength(Object array)
                               throws IllegalArgumentException

      Returns the length of the specified array object, as an `int`.
      Parameters:
        `array` - the array
      Returns:
        the length of the array
      Throws:
        `IllegalArgumentException` - if the object argument is not an array

    - #### get

          public static Object get(Object array,
                                   int index)
                            throws IllegalArgumentException,
                                   ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object. The value is automatically wrapped in an object if it has a primitive type.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the (possibly wrapped) value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array

    - #### getBoolean

          public static boolean getBoolean(Object array,
                                           int index)
                                    throws IllegalArgumentException,
                                           ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `boolean`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getByte

          public static byte getByte(Object array,
                                     int index)
                              throws IllegalArgumentException,
                                     ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `byte`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getChar

          public static char getChar(Object array,
                                     int index)
                              throws IllegalArgumentException,
                                     ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `char`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getShort

          public static short getShort(Object array,
                                       int index)
                                throws IllegalArgumentException,
                                       ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `short`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getInt

          public static int getInt(Object array,
                                   int index)
                            throws IllegalArgumentException,
                                   ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as an `int`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getLong

          public static long getLong(Object array,
                                     int index)
                              throws IllegalArgumentException,
                                     ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `long`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getFloat

          public static float getFloat(Object array,
                                       int index)
                                throws IllegalArgumentException,
                                       ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `float`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### getDouble

          public static double getDouble(Object array,
                                         int index)
                                  throws IllegalArgumentException,
                                         ArrayIndexOutOfBoundsException

      Returns the value of the indexed component in the specified array object, as a `double`.
      Parameters:
        `array` - the array
        `index` - the index
      Returns:
        the value of the indexed component in the specified array
      Throws:
        `NullPointerException` - If the specified object is null
        `IllegalArgumentException` - If the specified object is not an array, or if the indexed element cannot be converted to the return type by an identity or widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `get(java.lang.Object, int)`

    - #### set

          public static void set(Object array,
                                 int index,
                                 Object value)
                          throws IllegalArgumentException,
                                 ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified new value. The new value is first automatically unwrapped if the array has a primitive component type.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `value` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the array component type is primitive and an unwrapping conversion fails
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array

    - #### setBoolean

          public static void setBoolean(Object array,
                                        int index,
                                        boolean z)
                                 throws IllegalArgumentException,
                                        ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `boolean` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `z` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setByte

          public static void setByte(Object array,
                                     int index,
                                     byte b)
                              throws IllegalArgumentException,
                                     ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `byte` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `b` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setChar

          public static void setChar(Object array,
                                     int index,
                                     char c)
                              throws IllegalArgumentException,
                                     ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `char` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `c` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setShort

          public static void setShort(Object array,
                                      int index,
                                      short s)
                               throws IllegalArgumentException,
                                      ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `short` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `s` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setInt

          public static void setInt(Object array,
                                    int index,
                                    int i)
                             throws IllegalArgumentException,
                                    ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `int` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `i` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setLong

          public static void setLong(Object array,
                                     int index,
                                     long l)
                              throws IllegalArgumentException,
                                     ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `long` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `l` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setFloat

          public static void setFloat(Object array,
                                      int index,
                                      float f)
                               throws IllegalArgumentException,
                                      ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `float` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `f` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

    - #### setDouble

          public static void setDouble(Object array,
                                       int index,
                                       double d)
                                throws IllegalArgumentException,
                                       ArrayIndexOutOfBoundsException

      Sets the value of the indexed component of the specified array object to the specified `double` value.
      Parameters:
        `array` - the array
        `index` - the index into the array
        `d` - the new value of the indexed component
      Throws:
        `NullPointerException` - If the specified object argument is null
        `IllegalArgumentException` - If the specified object argument is not an array, or if the specified value cannot be converted to the underlying array's component type by an identity or a primitive widening conversion
        `ArrayIndexOutOfBoundsException` - If the specified `index` argument is negative, or if it is greater than or equal to the length of the specified array
      See Also:
        `set(java.lang.Object, int, java.lang.Object)`

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