Module java.base
Package 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.

Since:
1.1

  • Method Summary

    Modifier and Type
    Method
    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 length)
    Creates a new array with the specified component type and length.
    static Object
    newInstance​(Class<?> componentType, int... dimensions)
    Creates a new array with the specified component type and dimensions.
    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 declared in class java.lang.Object

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

  • Method Details

    • 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)