I done this code for Add and Remove the elements from the arraylist. But I can't complete the remove method of this code.
Can anyone help me for implement the remove method which is created in this code?
package Comp10152_linkedlist;
/**
*
* @author Bhumi-Kishan
*/
public class SimpleArrayList {
// Constants for the default capacity and
// the resizing factor.
private final int DEFAULT_CAPACITY = 10;
private final int RESIZE_FACTOR = 2;
// Private Fields
private String[] list; // The list
private int elements; // Number of elements stored
/** This constructor creates an empty list of the
default capacity.
*/
public SimpleArrayList()
{
list = new String[DEFAULT_CAPACITY];
elements = 0;
}
/** Add a string to the end of the list.
@param str The string to add.
*/
public void add(String str)
{
// To be completedint
// Hint - once you know the correct spot to place the elemnt use the
// private add method to place the item in the correct place
//
}
/** Add a string at a specific index.
@param index The added string's position.
@param str The string to add.
@exception IndexOutOtBoundsException When index
is out of bounds.
*/
public void add(int index, String str)
{
// First make sure the index is valid.
if (index > elements || index < 0)
throw new IndexOutOfBoundsException();
// If the list is full, resize it.
if (elements == list.length)
resize();
// Shift the elements starting at index
// to the right one position.
for (int index2 = elements; index2 > index; index2--)
list[index2] = list[index2 - 1];
// Add the new element at index.
list[index] = str;
// Adjust the number of elements.
elements++;
}
/** Search the list for a specified string.
@param str The string to search for.
@return true if the list contains the string;
false otherwise.
*/
public boolean contains(String str)
{
int index = 0; // Index counter
boolean found = false; // Search flag
// Step through the list. When the string
// is found, set found to true and stop.
while (!found && index < elements)
{
if (list[index].equals(str))
found = true;
index++;
}
// Return the status of the search.
return found;
}
/** Get an element at a specific position.
@param index The specified index.
@return The element at index.
@exception IndexOutOtBoundsException When index
is out of bounds.
*/
public String get(int index)
{
if (index >= elements || index < 0)
throw new IndexOutOfBoundsException();
return list[index];
}
/** Determines whether the list is empty.
@return true if the list is empty; false otherwise.
*/
public boolean isEmpty()
{
return (elements == 0);
}
/** Remove a specific string from the list.
@param str The string to remove.
@return true if the string was found; false otherwise.
*/
public boolean remove(String str)
{
// Hint : use text examples to assist or refer to the private add method above
return false;
}
/** Get the number of elements in the list.
@return The number of elements in the list.
*/
public int size()
{
return elements;
}
/** Resizes the list to twice its current length. */
private void resize()
{
// Calculate the new length, which is the current
// length multiplied by the resizing factor.
int newLength = list.length * RESIZE_FACTOR;
// Create a new list.
String[] tempList = new String[newLength];
// Copy the existing elements to the new list.
for (int index = 0; index < elements; index++)
tempList[index] = list[index];
// Replace the existing list with the new one.
list = tempList;
}
/** Convert the list to a String
@return A String with the same elements as the list.
*/
public String toString()
{
StringBuilder strBuilder = new StringBuilder();
// Use p to walk down the linked list
// Store the elements in the array.
for (int index = 0; index < elements; index++)
strBuilder.append("[" + list[index] + "]");
// Return the String.
return strBuilder.toString();
}
}
我在下面的主类中调用这个上层Simplearraylist类方法。我不知道SimpleArrayList类中remove方法的实现。任何人都可以给我一个解决方案吗？主要的是我不希望在主类中有任何改变。我只想根据它在main类中的调用实现remove方法的删除方法。 / * *要更改此许可证标题，请在“项目属性”中选择“许可证标题”。 *要更改此模板文件，请选择“工具”|模板 *并在编辑器中打开模板。 * /
package Comp10152_linkedlist;
/**
*
* @author Bhumi-Kishan
*/
import java.util.Random;
public class Comp10152_Lab4
{
public static void main(String[] args)
{
final int NUMBER_OF_ITERATIONS = 10;
String names[] = {"Amy", "Bob", "Al", "Beth", "Carol", "Zed", "Aaron"};
SimpleLinkedList ll = new SimpleLinkedList();
final int TOTALOPERATIONS = names.length * NUMBER_OF_ITERATIONS;
Random random = new Random();
for (int i=0; i<NUMBER_OF_ITERATIONS;i++)
{
for (int j=0; j<names.length; j++)
ll.add(names[j]);
}
System.out.println("The members of list are:");
System.out.println(ll);
// remove half of the items in the list by selecting randomly from names
for (int i=0; i<TOTALOPERATIONS/2;i++)
{
ll.remove(names[random.nextInt(names.length)]);
}
System.out.println("The members of list are:");
System.out.println(ll);
SimpleArrayList al = new SimpleArrayList();
for (int i=0; i<NUMBER_OF_ITERATIONS;i++)
{
for (int j=0;j<names.length;j++)
al.add(i,names[j]);
}
System.out.println("The members of array are:");
System.out.println(al);
// remove half of the items in the list by selecting randomly from names
for (int i=0; i<TOTALOPERATIONS/2;i++)
{
al.remove(names[random.nextInt(names.length)]);
}
System.out.println("The members of array are:");
System.out.println(al);
}
}
答案 0 :(得分：1)
假设您只需删除第一次出现，IAW使用ArrayList #remove（Object）方法：
public boolean remove(String str) {
for (int i=0;i<list.length;i++) {
final String s = list[i];
if (str == s || s.contentEquals(str)) {
String[] newList = new String[list.length];
System.arraycopy(list, 0, newList ,0, i);
if (list.length > i+1) {
System.arraycopy(list, i+1, newList, i, list.length - 1 - i);
}
list = newList;
elements--;
return true;
}
}
return false;
}
编辑：为删除方法添加了单元测试
public class SimpleArrayListTest {
@Test
public void testRemove() {
final String ONE = "one";
final String TWO = "two";
final String THREE = "three";
SimpleArrayList l = new SimpleArrayList();
l.add(0,ONE);
l.add(1,TWO);
l.add(2,THREE);
l.remove(TWO);
assertEquals(2, l.size());
assertTrue(l.contains(ONE));
assertTrue(l.contains(THREE));
l.remove(ONE);
assertEquals(1, l.size());
assertTrue(l.contains(THREE));
l.remove(THREE);
assertEquals(0, l.size());
}
}
答案 1 :(得分：0)
遍历列表，检查字符串是否匹配删除并返回true
public boolean remove(String str)
{
// Hint : use text examples to assist or refer to the private add method above
for ( int i = 0; i < list.size(); i++){
String tempName = list.get(i);
if(tempName.equals(str){
name.remove(i);
return true;
}
return false;
}
}
从此列表中删除第一次出现的指定元素， 如果它存在。如果列表不包含该元素，则为 不变。
答案 2 :(得分：0)
如何使用java泛型集合，请参考以下解决方案：
多次删除：多次出现给定字符串值
public boolean remove(String str) {
int previousLength =list.length;
List<string> newList = new ArrayList<string>();
for (int i=0;i<previousLength;i++) {
final String s = list[i];
if (str == s || s.contentEquals(str)) {
continue;
}
list.add(s);
}
list = newList.toArray(new String[newList.size()]);
//if same size then no element found and no delete operation => 5!=5 returns "false"
//if different size then element is deleted => 4!=5 returns "true"
return list.length!=previousLength;
}
对于单次删除：多次/单次出现
public boolean remove(String str) {
int previousLength =list.length;
List<string> newList = new ArrayList<string>();
for (int i=0;i<previousLength;i++) {
final String s = list[i];
if (str == s || s.contentEquals(str)) {
for (int j=i+1;j<previousLength;j++) {
s = list[j];
list.add(s);
}
break; //https://stackoverflow.com/questions/462373/difference-between-break-and-continue-statement
}
list.add(s);
}
list = newList.toArray(new String[newList.size()]);
//if same size then no element found and no delete operation => 5!=5 returns "false"
//if different size then element is deleted => 4!=5 returns "true"
return list.length!=previousLength;
}
希望这会有所帮助......
<强>参考：
https://thenewcircle.com/static/bookshelf/java_fundamentals_tutorial/generics_collections.html http://www.tutorialspoint.com/java/java_generics.htm Difference between break and continue statement