Given the following class in Java : public class ThreeTenDynArray<T> { //default initial capacity / minimum capacity private static final int MIN_CAPACITY = 2; //underlying array for storage -- you MUST use this for credit! //Do NOT change the name or type private T[] data; private int size = 0; private int capacity = 0; // ADD MORE PRIVATE MEMBERS HERE IF NEEDED! /** * */ @SuppressWarnings("unchecked") public ThreeTenDynArray() { // Constructor // Initial capacity of the storage should be MIN_CAPACITY // Hint: Can't remember how to make an array of generic Ts? It's in the textbook... data = (T[])(new Object[MIN_CAPACITY]); size = 0; capacity = MIN_CAPACITY; } /** * @param initCapacity */ @SuppressWarnings("unchecked") public ThreeTenDynArray(int initCapacity) { // Constructor // Initial capacity of the storage should be initCapacity. // - Throw IllegalArgumentException if initCapacity is smaller than // MIN_CAPACITY 2 // - Use this _exact_ error message for the exception // (quotes are not part of the message): // "Capacity must be at least 2!" if (initCapacity < MIN_CAPACITY) { throw new IllegalArgumentException("Capacity must be at least 2!"); } } /** * @return */ public int size() { // Report the current number of elements // O(1) return size; //default return, remove/change as needed } /** * @return */ public int capacity() { // Report max number of elements of the current storage // (subject to change since this is a _dynamic_ ) // O(1) return capacity; //default return, remove/change as needed } /** * @param index index you're changing * @param value what you're adding * @return the old item at the index */ public T set(int index, T value) { // Replace the item at the given index to be the given value. // Return the old item at that index. // Note: You cannot add new items (i.e. cannot increase size) with this method. // O(1) //return firstIndexOf(value); // - Throw IndexOutOfBoundsException if index is not valid // - Use this code to produce the correct error message for // the exception (do not use a different message): // "Index: " + index + " out of bounds!" if (index < 0 && index >= size) { throw new IndexOutOfBoundsException("Index: " + index + " out of bounds!"); } // - Throw IllegalArgumentException if value is null. // - Use this _exact_ error message for the exception // (quotes are not part of the message): // "Cannot include null values!" if (value==null) { throw new IllegalArgumentException("Cannot include null values!"); } T oldValue = data[index]; data[index] = value; return oldValue; //default return, remove/change as needed } /** * @param index * @return */ public T get(int index) { // Return the item at the given index if (index < 0 && index >= size) { throw new IndexOutOfBoundsException("Index: " + index + " out of bounds!"); } // O(1) // Use the exception (and error message) described in set() // for invalid indicies. return data[index]; //default return, remove/change as needed } /** * @param value */ @SuppressWarn.

1. Given the following class in Java :
public class ThreeTenDynArray<T> {
//default initial capacity / minimum capacity
private static final int MIN_CAPACITY = 2;
//underlying array for storage -- you MUST use this for credit!
//Do NOT change the name or type
private T[] data;
private int size = 0;
private int capacity = 0;
// ADD MORE PRIVATE MEMBERS HERE IF NEEDED!
/**
*
*/
@SuppressWarnings("unchecked")
public ThreeTenDynArray() {
// Constructor
// Initial capacity of the storage should be MIN_CAPACITY
// Hint: Can't remember how to make an array of generic Ts? It's in the textbook...
data = (T[])(new Object[MIN_CAPACITY]);
size = 0;
capacity = MIN_CAPACITY;
}
/**

2. * @param initCapacity
*/
@SuppressWarnings("unchecked")
public ThreeTenDynArray(int initCapacity) {
// Constructor
// Initial capacity of the storage should be initCapacity.
// - Throw IllegalArgumentException if initCapacity is smaller than
// MIN_CAPACITY 2
// - Use this _exact_ error message for the exception
// (quotes are not part of the message):
// "Capacity must be at least 2!"
if (initCapacity < MIN_CAPACITY) {
throw new IllegalArgumentException("Capacity must be at least 2!");
}
}
/**
* @return
*/
public int size() {
// Report the current number of elements
// O(1)
return size; //default return, remove/change as needed
}

3. /**
* @return
*/
public int capacity() {
// Report max number of elements of the current storage
// (subject to change since this is a _dynamic_ )
// O(1)
return capacity; //default return, remove/change as needed
}
/**
* @param index index you're changing
* @param value what you're adding
* @return the old item at the index
*/
public T set(int index, T value) {
// Replace the item at the given index to be the given value.
// Return the old item at that index.
// Note: You cannot add new items (i.e. cannot increase size) with this method.
// O(1)
//return firstIndexOf(value);
// - Throw IndexOutOfBoundsException if index is not valid
// - Use this code to produce the correct error message for
// the exception (do not use a different message):

4. // "Index: " + index + " out of bounds!"
if (index < 0 && index >= size) {
throw new IndexOutOfBoundsException("Index: " + index + " out of bounds!");
}
// - Throw IllegalArgumentException if value is null.
// - Use this _exact_ error message for the exception
// (quotes are not part of the message):
// "Cannot include null values!"
if (value==null) {
throw new IllegalArgumentException("Cannot include null values!");
}
T oldValue = data[index];
data[index] = value;
return oldValue; //default return, remove/change as needed
}
/**
* @param index
* @return
*/
public T get(int index) {
// Return the item at the given index
if (index < 0 && index >= size) {
throw new IndexOutOfBoundsException("Index: " + index + " out of bounds!");

5. }
// O(1)
// Use the exception (and error message) described in set()
// for invalid indicies.
return data[index]; //default return, remove/change as needed
}
/**
* @param value
*/
@SuppressWarnings("unchecked")
public void append(T value) {
// Append an element to the end of the storage.
// Double the capacity if no space available.
// Code reuse! Consider using setCapacity (see below).
// For a null value, use the same exception and message
// as set().
// You can assume we will never need to grow the capacity to a value
// beyond Integer.MAX_VALUE/4. No need to check or test that boundary
// value when you grow the capacity.
// Amortized O(1)
// - Throw IllegalArgumentException if value is null.
// - Use the same error message as set().
if (value==null) {

6. throw new IllegalArgumentException("Cannot include null values!");
}
if (size < capacity) {
data[size] = value;
size++;
}
else{
capacity *= 2;
T[] data2 = (T[])(new Object[capacity]);
for (int i =0; i < data.length; i++) {
data2[i] = data[i];
}
data = data2;
data[size] = value;
size++;
}
}
/**
* @param index
* @param value
*/
@SuppressWarnings("unchecked")
public void insert(int index, T value) {

7. // Insert the given value at the given index and shift elements if needed.
// You _can_ append items with this method.
// Double capacity if no space available.
// Assume the same as append() for the upper bound of capacity.
// Code reuse! Consider using setCapacity (see below).
// For an invalid index or a null value, use the same exception and message
// as set(). However, remember that the condition of the exception is
// different (a different invalid range for indexes).
if (index >= capacity || index < 0 ) {
throw new IndexOutOfBoundsException("Index: " + index + " out of bounds!");
}
for (int i = size-1; i >= index; i--) {
data[i+1] = data[i];
}
data[index] = value;
size++;
// O(N) where N is the number of elements in the storage
}
/**
* @param index
* @return
*/
@SuppressWarnings("unchecked")

8. public T remove(int index) {
// Remove and return the element at the given index. Shift elements
// to ensure no gap. Throw an exception when there is an invalid
// index (see set(), get(), etc. above).
// Halve capacity (rounding down) of the storage if the number of elements falls
// below or at 1/4 of the capacity.
// However, capacity should NOT go below MIN_CAPACITY.
// Code reuse! Consider using setCapacity (see below).
// O(N) where N is the number of elements currently in the storage
if (index >= capacity || index < 0 ) {
throw new IndexOutOfBoundsException("Index: " + index + " out of bounds!");
}
T oldValue = data[index];
for (int i = index; i < data.length-1; i++) {
data[i] = data[i + 1];
}
size--;
if(size<=capacity/4)
{
capacity/=2;
if(capacity<MIN_CAPACITY)
capacity = MIN_CAPACITY;
}

9. return oldValue ; //default return, remove/change as needed
}
/**
* @param newCapacity
* @return
*/
@SuppressWarnings("unchecked")
public boolean setCapacity(int newCapacity) {
// Change the max number of items allowed before next expansion to newCapacity.
// No other changes to the current values in storage
// (i.e. they should all keep the same index).
// Capacity should not be changed if:
// - newCapacity is below MIN_CAPACITY; or
// - newCapacity is not large enough to accommodate current number of items
// Return false if newCapacity cannot be applied; return true otherwise.
// Special case: if newCapacity is identical to the current max number of items,
// no need to change anything but still return true.
// O(N) where N is the number of elements in the array
if (newCapacity < MIN_CAPACITY || newCapacity < size) {
return false; //default return, remove/change as needed
}
else if (newCapacity == size) {
return true;

10. }
return false;
}
/**
* @param value
* @return
*/
public int firstIndexOf(T value) {
// Return the index of the first occurrence of value or -1 if not found.
// NOTES: - Remember null is not a valid item in list.
// - Remember to use .equals for comparison of non-null values.
// O(N) where N is the number of elements in the list
if (value==null) {
return -1;
}
return -1; //default return, remove/change as needed
}
Please explain these errors and how to fix them.
Errors when testing:
1) test_append3(ThreeTenDynArrayTester)
java.lang.NullPointerException: Cannot read the array length because "this.data" is null
at ThreeTenDynArray.append(ThreeTenDynArray.java:161)
at ThreeTenDynArrayTester.test_append3(ThreeTenDynArrayTester.java:146)

11. at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.ja
va:77)
at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccesso
rImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at
org.junit.internal.runners.statements.FailOnTimeout$StatementThread.run(FailOnTimeout.java:7
4)
2) test_setCapacity1(ThreeTenDynArrayTester)
java.lang.AssertionError: Capacity failed to grow, expected capacity 8
at org.junit.Assert.fail(Assert.java:88)
at org.junit.Assert.assertTrue(Assert.java:41)
at ThreeTenDynArrayTester.test_setCapacity1(ThreeTenDynArrayTester.java:694)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.ja
va:77)
at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccesso
rImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)

12. at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at
org.junit.internal.runners.statements.FailOnTimeout$StatementThread.run(FailOnTimeout.java:7
4)
3) test_constructor2(ThreeTenDynArrayTester)
java.lang.AssertionError: Initial capacity of the storage has incorrect initCapacity
at org.junit.Assert.fail(Assert.java:88)
at org.junit.Assert.assertTrue(Assert.java:41)
at ThreeTenDynArrayTester.test_constructor2(ThreeTenDynArrayTester.java:90)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at
java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.ja
va:77)
at
java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccesso
rImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:568)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:47)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:44)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at
org.junit.internal.runners.statements.FailOnTimeout$StatementThread.run(FailOnTimeout.java:7
4)