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| 12. 6. 1. 定义一个泛型类型 |
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import java.awt.Point;
class ListItem {
public ListItem(Object item) {
this.item = item;
next = null;
}
public String toString() {
return "ListItem " + item;
}
ListItem next;
Object item;
}
class LinkedList<T> {
public LinkedList() {
}
public LinkedList(T item) {
if (item != null) {
current = end = start = new ListItem(item);
}
}
public LinkedList(T[] items) {
if (items != null) {
for (int i = 0; i < items.length; i++) {
addItem(items[i]);
}
current = start;
}
}
public void addItem(T item) {
ListItem newEnd = new ListItem(item);
if (start == null) {
start = end = newEnd;
} else {
end.next = newEnd;
end = newEnd;
}
}
public T getFirst() {
current = start;
return start == null ? null : start.item;
}
public T getNext() {
if (current != null) {
current = current.next;
}
return current == null ? null : current.item;
}
private ListItem start = null;
private ListItem end = null;
private ListItem current = null;
private class ListItem {
public ListItem(T item) {
this.item = item;
next = null;
}
public String toString() {
return "ListItem " + item;
}
ListItem next;
T item;
}
}
public class MainClass {
public static void main(String[] a) {
LinkedList<Point> polyline = new LinkedList<Point>();
polyline.addItem(new Point(1, 2));
polyline.addItem(new Point(2, 3));
Point p = polyline.getFirst();
System.out.println(p);
}
}
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java.awt.Point[x=1,y=2] |
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