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java.lang.ArrayStoreException storing Integer in Integer array

0

Why am I getting this exception?

java.lang.ArrayStoreException: java.lang.Integer
at MyLinkedList.toArray(MyLinkedList.java:94)
at MyLinkedListTest.toArray_ReturnGenericArray(MyLinkedListTest.java:80)

I am creating an Integer array and passing in Integer values. Why then, when I create a new instance of the same type of array, am I unable to assign integer values to it?

@Override
public <T1> T1[] toArray(T1[] a) 
 if (a.length < size) 
 a = (T1[]) java.lang.reflect.Array.newInstance(a.getClass(), size);
 
 Node<T> current = head;
 int i = 0;
 Object[] result = a;
 while (current != null) 
 result[i] = current.value;
 i++;
 current = current.next;
 
 // if array has room to spare set element immediately following end of list to null
 if (a.length > i) 
 a[i] = null;
 
 return a;


@Test
void toArray_ReturnGenericArray() 
 Integer[] array2 = linkedList.toArray(new Integer[4]);
 assertEquals(1, array2[0]);
 assertEquals(2, array2[1]);
 assertEquals(3, array2[2]);
 assertEquals(4, array2[3]);
 assertEquals(5, array2[4]);
 assertEquals(5, array2.length);

java arrays

share|improve this question

asked Mar 7 at 16:50

Co CodesCo Codes

31

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Use java.util.Arrays#copyOf(U[], int, java.lang.Class<? extends T[]>)
  
  – luk2302
  Mar 7 at 16:57
  

  
  
  
  

add a comment | 

0

Why am I getting this exception?

java.lang.ArrayStoreException: java.lang.Integer
at MyLinkedList.toArray(MyLinkedList.java:94)
at MyLinkedListTest.toArray_ReturnGenericArray(MyLinkedListTest.java:80)

I am creating an Integer array and passing in Integer values. Why then, when I create a new instance of the same type of array, am I unable to assign integer values to it?

@Override
public <T1> T1[] toArray(T1[] a) 
 if (a.length < size) 
 a = (T1[]) java.lang.reflect.Array.newInstance(a.getClass(), size);
 
 Node<T> current = head;
 int i = 0;
 Object[] result = a;
 while (current != null) 
 result[i] = current.value;
 i++;
 current = current.next;
 
 // if array has room to spare set element immediately following end of list to null
 if (a.length > i) 
 a[i] = null;
 
 return a;


@Test
void toArray_ReturnGenericArray() 
 Integer[] array2 = linkedList.toArray(new Integer[4]);
 assertEquals(1, array2[0]);
 assertEquals(2, array2[1]);
 assertEquals(3, array2[2]);
 assertEquals(4, array2[3]);
 assertEquals(5, array2[4]);
 assertEquals(5, array2.length);

java arrays

share|improve this question

asked Mar 7 at 16:50

Co CodesCo Codes

31

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Use java.util.Arrays#copyOf(U[], int, java.lang.Class<? extends T[]>)
  
  – luk2302
  Mar 7 at 16:57
  

  
  
  
  

add a comment | 

Why am I getting this exception?

java.lang.ArrayStoreException: java.lang.Integer
at MyLinkedList.toArray(MyLinkedList.java:94)
at MyLinkedListTest.toArray_ReturnGenericArray(MyLinkedListTest.java:80)

I am creating an Integer array and passing in Integer values. Why then, when I create a new instance of the same type of array, am I unable to assign integer values to it?

@Override
public <T1> T1[] toArray(T1[] a) 
 if (a.length < size) 
 a = (T1[]) java.lang.reflect.Array.newInstance(a.getClass(), size);
 
 Node<T> current = head;
 int i = 0;
 Object[] result = a;
 while (current != null) 
 result[i] = current.value;
 i++;
 current = current.next;
 
 // if array has room to spare set element immediately following end of list to null
 if (a.length > i) 
 a[i] = null;
 
 return a;


@Test
void toArray_ReturnGenericArray() 
 Integer[] array2 = linkedList.toArray(new Integer[4]);
 assertEquals(1, array2[0]);
 assertEquals(2, array2[1]);
 assertEquals(3, array2[2]);
 assertEquals(4, array2[3]);
 assertEquals(5, array2[4]);
 assertEquals(5, array2.length);

java arrays

share|improve this question

asked Mar 7 at 16:50

Co CodesCo Codes

31

java.lang.ArrayStoreException: java.lang.Integer
at MyLinkedList.toArray(MyLinkedList.java:94)
at MyLinkedListTest.toArray_ReturnGenericArray(MyLinkedListTest.java:80)

@Override
public <T1> T1[] toArray(T1[] a) 
 if (a.length < size) 
 a = (T1[]) java.lang.reflect.Array.newInstance(a.getClass(), size);
 
 Node<T> current = head;
 int i = 0;
 Object[] result = a;
 while (current != null) 
 result[i] = current.value;
 i++;
 current = current.next;
 
 // if array has room to spare set element immediately following end of list to null
 if (a.length > i) 
 a[i] = null;
 
 return a;


@Test
void toArray_ReturnGenericArray() 
 Integer[] array2 = linkedList.toArray(new Integer[4]);
 assertEquals(1, array2[0]);
 assertEquals(2, array2[1]);
 assertEquals(3, array2[2]);
 assertEquals(4, array2[3]);
 assertEquals(5, array2[4]);
 assertEquals(5, array2.length);

share|improve this question

asked Mar 7 at 16:50

Co CodesCo Codes

31

share|improve this question

asked Mar 7 at 16:50

Co CodesCo Codes

31

asked Mar 7 at 16:50

Co CodesCo Codes

31

asked Mar 7 at 16:50

Co CodesCo Codes

31

1 Answer
1

active

oldest

votes

1

The main issue is this bit of code

a.getClass()

What it will return is not the class of the component of the array, but the array itself, e.g.

[Ljava.lang.Integer

See the [L prefix. You need to use

a.getClass().getComponentType()

As Array#newInstance accepts the component type

newInstance(Class<?> componentType, int length)

share|improve this answer

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647

add a comment | 

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1

The main issue is this bit of code

a.getClass()

What it will return is not the class of the component of the array, but the array itself, e.g.

[Ljava.lang.Integer

See the [L prefix. You need to use

a.getClass().getComponentType()

As Array#newInstance accepts the component type

newInstance(Class<?> componentType, int length)

share|improve this answer

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647

add a comment | 

1

The main issue is this bit of code

a.getClass()

What it will return is not the class of the component of the array, but the array itself, e.g.

[Ljava.lang.Integer

See the [L prefix. You need to use

a.getClass().getComponentType()

As Array#newInstance accepts the component type

newInstance(Class<?> componentType, int length)

share|improve this answer

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647

add a comment | 

The main issue is this bit of code

a.getClass()

What it will return is not the class of the component of the array, but the array itself, e.g.

[Ljava.lang.Integer

See the [L prefix. You need to use

a.getClass().getComponentType()

As Array#newInstance accepts the component type

newInstance(Class<?> componentType, int length)

share|improve this answer

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647

a.getClass()

[Ljava.lang.Integer

a.getClass().getComponentType()

newInstance(Class<?> componentType, int length)

share|improve this answer

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647

answered Mar 7 at 17:01

LppEddLppEdd

9,09621647