You can find ArrayLinearLists from here in EPROGS 尝试将.txt文件中的数据排序到三个不同的ArrayLinearLists中。但是问题在于他们的能力。每当调用.add函数时，容量都会加倍。
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
String line;
int indexOfCode = 0;
int indexOfName = 1;
int indexOfCredit = 2;
int count = 0;
ArrayLinearList codeR = new ArrayLinearList();
ArrayLinearList nameR = new ArrayLinearList();
ArrayLinearList creditR = new ArrayLinearList();
try (BufferedReader br = new BufferedReader(new FileReader("Subjects.txt"))) {
while ((line = br.readLine()) != null) {
String values[] = line.split("/");
codeR.add(0, values[indexOfCode]);
nameR.add(0, values[indexOfName]);
creditR.add(0, values[indexOfCredit]);
}
System.out.println(codeR);
System.out.println(nameR);
System.out.println(creditR);
}
}
}
这是ArrayLinearList代码
protected Object[] element; // array of elements
protected static int size; // number of elements in array
protected static ArrayLinearList theObject;
// constructors
/**
* create a list with initial capacity initialCapacity
*
* @throws IllegalArgumentException
* when initialCapacity < 1
*/
public ArrayLinearList(int initialCapacity) {
if (initialCapacity < 1)
throw new IllegalArgumentException("initialCapacity must be >= 1");
// size has the default initial value of 0
element = new Object[initialCapacity];
}
/** create a list with initial capacity 10 */
public ArrayLinearList() {// use default capacity of 10
this(10);
}
// methods
/** @return true iff list is empty */
public boolean isEmpty() {
return size == 0;
}
/** @return current number of elements in list */
public int size() {
return size;
}
/**
* @throws IndexOutOfBoundsException
* when index is not between 0 and size - 1
*/
void checkIndex(int index) {
if (index < 0 || index >= size)
throw new IndexOutOfBoundsException("index = " + index + " size = " + size);
}
/**
* @return element with specified index
* @throws IndexOutOfBoundsException
* when index is not between 0 and size - 1
*/
public Object get(int index) {
checkIndex(index);
return element[index];
}
/**
* @return index of first occurrence of theElement, return -1 if theElement
* not in list
*/
public int indexOf(Object theElement) {
// search element[] for theElement
for (int i = 0; i < size; i++)
if (element[i].equals(theElement))
return i;
// theElement not found
return -1;
}
/**
* Remove the element with specified index. All elements with higher index
* have their index reduced by 1.
*
* @throws IndexOutOfBoundsException
* when index is not between 0 and size - 1
* @return removed element
*/
public Object remove(int index) {
checkIndex(index);
// valid index, shift elements with higher index
Object removedElement = element[index];
for (int i = index + 1; i < size; i++)
element[i - 1] = element[i];
element[--size] = null; // enable garbage collection
return removedElement;
}
/**
* Insert an element with specified index. All elements with equal or higher
* index have their index increased by 1.
*
* @throws IndexOutOfBoundsException
* when index is not between 0 and size
*/
public void add(int index, Object theElement) {
if (index < 0 || index > size)
// invalid list position
throw new IndexOutOfBoundsException("index = " + index + " size = " + size);
// valid index, make sure we have space
if (size == element.length)
// no space, double capacity
element = ChangeArrayLength.changeLength1D(element,2* size);
// shift elements right one position
for (int i = size - 1; i >= index; i--)
element[i + 1] = element[i];
element[index] = theElement;
size++;
}
/** convert to a string */
public String toString() {
StringBuffer s = new StringBuffer("[");
// put elements into the buffer
for (int i = 0; i < size; i++)
if (element[i] == null)
s.append("null, ");
else
s.append(element[i].toString() + ", ");
if (size > 0)
s.delete(s.length() - 2, s.length()); // remove last ", "
s.append("]");
// create equivalent String
return new String(s);
}
/** create and return an iterator */
public Iterator iterator() {
return new ArrayLinearListIterator((MyArrayList) this);
}
/** test program */
public static void main(String[] args) {
// test default constructor
LinearList x = new ArrayLinearList();
// test size
System.out.println("Initial size is " + x.size());
// test isEmpty
if (x.isEmpty())
System.out.println("The list is empty");
else
System.out.println("The list is not empty");
// test put
x.add(0, new Integer(2));
x.add(1, new Integer(6));
x.add(0, new Integer(1));
x.add(2, new Integer(4));
System.out.println("List size is " + x.size());
// test toString
System.out.println("The list is " + x);
// test indexOf
int index = x.indexOf(new Integer(4));
if (index < 0)
System.out.println("4 not found");
else
System.out.println("The index of 4 is " + index);
index = x.indexOf(new Integer(3));
if (index < 0)
System.out.println("3 not found");
else
System.out.println("The index of 3 is " + index);
// test get
System.out.println("Element at 0 is " + x.get(0));
System.out.println("Element at 3 is " + x.get(3));
// test remove
System.out.println(x.remove(1) + " removed");
System.out.println("The list is " + x);
System.out.println(x.remove(2) + " removed");
System.out.println("The list is " + x);
if (x.isEmpty())
System.out.println("The list is empty");
else
System.out.println("The list is not empty");
System.out.println("List size is " + x.size());
}
}
在此先感谢伟大的高级开发人员：D
最佳答案
对于使用ArrayLinearList的开发人员，这意味着提供更大的初始容量，以防止增加太多。
使用估算：
Path path = Paths.get("Subjects.txt");
int initialCapacity = (int)(Files.size(path) / 3);
对于实现ArrayLinearList的开发人员，她可以选择更大的默认初始容量，或者类似的方式，将数组的大小增加
1000 + array.length/4，以不占用太多的空间，并且最初没有太多重复的增加。