对于我目前的作业,我试图通过一个通用类对我的数组进行排序,因为用户将值插入到它的位置。当大小读取为完全加载时,数组类会调用一个扩展方法,该方法会增加数组的大小,同时将其值保留在适当的位置,这是我从教授的笔记中遵循的。出于某种原因,除 location[0] 之外的所有值似乎都放错了位置或从数组中删除了。我倾向于问题出在扩展方法上,但我不知道如何解决这个问题。
例如,初始大小当前设置为 5,但在调用扩展方法时增加 3。用户可以完美地输入值 1,2,3,4,5。但是当用户输入新值 6 时会调用扩展,该值会输出 1、6、null、null、null、null 的数组。任何进一步将导致错误“线程“主”java.lang.NullPointerException中的异常”
这是我的排序数组类:
public class SortedArray {
private int size;
private int increment;
private int top;
Comparable[] a;
public SortedArray(int initialSize, int incrementAmount)
{
top = -1;
size = initialSize;
increment = incrementAmount;
a = new Comparable [size];
}
public int appropriatePosition(Comparable value)
{
int hold = top;
if(hold == -1)
{
hold = 0;
}
else
{
for(int i = 0; i <= top; i++)
{
if(value.compareTo(a[i]) > 0)
{
hold = i + 1;
}
}
}
return hold;
}
public Comparable smallest()
{
return a[0];
}
public Comparable largest()
{
return a[top];
}
public void insert(Comparable value)// the method that my driver calls for.
{
int ap = appropriatePosition(value);
//Expansion if full
if(full() == true)
{
expansion();
}
//Shifting numbers to top
for(int i = top; i >= ap ; i--)
{
{
a[i + 1] = a[i];
}
}
a[ap] = value;
top++;
}
public boolean full()
{
if(top == a.length -1)
{
return true;
}
else
{
return false;
}
}
public void expansion()//here's where the expansion begins
{
int newSize = a.length + increment;
Comparable[] tempArray = new Comparable[newSize];
for(int i= 0; i < a.length; i++)
{
tempArray[i]= a[i];
a = tempArray;
}
}
这是我的驱动程序类,它调用 SortedArray 类中的 insert 方法。
public class IntDriver {
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
//Creating variables
int data;
boolean check = false;
int choice;
int size = 5;
int increment = 3;
SortedArray b = new SortedArray(size, increment);
//Creating Menu
System.out.println("Please choose through options 1-6.");
System.out.println("1. Insert\n2. Delete\n3. Clear\n4. Smallest\n5. Largest\n6. Exit\n7.Redisplay Menu");
while(check == false)
{
choice = keyboard.nextInt();
switch(choice)
{
case 1:
System.out.println("Type the int data to store in array location.");
data = keyboard.nextInt();
Integer insertObj = new Integer(data);
b.insert(insertObj);
System.out.println("The value " + data + " is inserted");
b.print();
break;