我一直在研究基于其索引将节点插入到链表中的项目,如果节点的索引为 == -1,则将其插入最后。
这是我在 LinkedLists 的第一次拍摄,所以我什至不确定我是否正确连接了这些东西,所以任何提示都会真正有帮助。
我已经能够按顺序将节点放入列表中,但是在第一个测试用例之后,我得到了一个空指针异常。
这是我的代码
--------------------LinkedListClass---------
package edu.wmich.cs1120.GudahWaleed.lab7.impl;
import edu.wmich.cs1120.lab7.interfaces.ICharNode;
import edu.wmich.cs1120.lab7.interfaces.IListCharNodes;
public class ListCharNodes implements IListCharNodes {
private int length;
private ICharNode lastNode;
private ICharNode firstNode;
public ListCharNodes() {
firstNode = new CharNode();
lastNode = null;
}
public boolean isEmpty() {
return firstNode == null;
}
public int size() {
int count = 0;
ICharNode p = firstNode;
while (p != null) {
count++;
p = p.getNext();
}
return count;
}
public ICharNode get_Symmetric(ICharNode node) {
ICharNode temp = firstNode.getNext();
for (int i = length / 2; i < length; i++) {
temp = temp.getNext();
}
return temp;
}
@Override
public ICharNode getFirstNode(ICharNode node) {
return firstNode;
}
@Override
public int getLength() {
return length;
}
public void insertCharNode(ICharNode node) {
int index = node.getIndex();
if (index == -1) {
insertCharNodeAtEnd(node);
}
else if (firstNode.getIndex() == node.getIndex()) {
node.setNext(firstNode.getNext());
firstNode = node;
return;
}
else if (index == 0) {
node.setNext(firstNode);
firstNode = node;
if (lastNode == null)
return;
}
if (index > 0) {
ICharNode pred = firstNode;
for (int k = 1; k <= index - 1; k++) {
pred = pred.getNext();
}
pred.setNext(new CharNode(node.getContent(), node.getIndex(), pred
.getNext()));
if (pred.getNext().getNext() == null)
lastNode = pred.getNext();
}
}
@Override
public void insertCharNodeAtEnd(ICharNode node) {
if (isEmpty()) {
firstNode = node;
lastNode = firstNode;
}
else {
lastNode.setNext(node);
lastNode = lastNode.getNext();
}
}
@Override
public boolean isPalindrome() {
ICharNode temp = firstNode;
int count = 0;
while (count < (length / 2)) {
ICharNode pal = get_Symmetric(temp);
if (pal.getContent() != temp.getContent()) {
return false;
} else
count++;
}
return true;
}
@Override
public void printMessage() {
ICharNode toPrint = firstNode;
while (toPrint != null) {
System.out.print(toPrint.getContent());
// System.out.print(toPrint.getIndex());
// System.out.print(length);
toPrint = toPrint.getNext();
}
}
@Override
public void setLength(int l) {
length = length + l;
}
}
---------------节点类--------
package edu.wmich.cs1120.GudahWaleed.lab7.impl;
import edu.wmich.cs1120.lab7.interfaces.ICharNode;
public class CharNode implements ICharNode {
private int index;
private char content;
private ICharNode next;
private ICharNode last;
public CharNode(char c, int i) {
setContent(c);
setIndex(i);
}
public CharNode(char c, int i, ICharNode next){
setContent(c);
setIndex(i);
setNext(next);
}
public CharNode(){
next = null;
}
@Override
public void setContent(char c) {
content = c;
}
@Override
public char getContent() {
return content;
}
@Override
public void setIndex(int i) {
index = i;
}
@Override
public int getIndex() {
return index;
}
@Override
public void setNext(ICharNode next) {
this.next=next;
}
@Override
public ICharNode getNext() {
return next;
}
}
----------------------测试类------------- ----
package edu.wmich.cs1120.GudahWaleed.lab7.impl;
import java.io.FileNotFoundException;
import java.io.IOException;
import edu.wmich.cs1120.lab7.interfaces.ICharNode;
//import edu.wmich.cs1120.lab7.interfaces.IGlyphMessage;
import edu.wmich.cs1120.lab7.interfaces.IListCharNodes;
//import edu.wmich.cs1120.lab7.interfaces.IStoneAnalysis;
/**
* @author sww
*
*/
@SuppressWarnings("unused")
public class Test {
/**
* @param args
* @throws IOException
* @throws FileNotFoundException
*/
public static void main(String[] args) throws FileNotFoundException, IOException {
/*IStoneAnalysis stone = new StoneAnalysis();
IGlyphMessage glpymsg = new GlyphMessage();
IListCharNodes list = new ListCharNodes();
stone.setGmsg(glpymsg);
glpymsg.setListCharNodes(list);
*/
IListCharNodes list = new ListCharNodes();
ICharNode n1 = new CharNode('a',1);
ICharNode n2 = new CharNode('b',0);
ICharNode n3 = new CharNode('a',2);
ICharNode n4 = new CharNode('b',-1);
list.insertCharNode(n1);
list.insertCharNode(n4);
list.insertCharNode(n3);
list.insertCharNode(n2);
System.out.print("Message 1 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n4);
list.insertCharNode(n1);
list.insertCharNode(n3);
list.insertCharNode(n2);
System.out.print("Message 2 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n4);
list.insertCharNode(n3);
list.insertCharNode(n1);
list.insertCharNode(n2);
System.out.print("Message 2.1 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n4);
list.insertCharNode(n2);
list.insertCharNode(n1);
list.insertCharNode(n3);
System.out.print("Message 2.2 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n4);
list.insertCharNode(n3);
list.insertCharNode(n2);
list.insertCharNode(n1);
System.out.print("Message 2.3 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n1);
list.insertCharNode(n2);
list.insertCharNode(n4);
list.insertCharNode(n3);
System.out.print("Message 3 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n3);
list.insertCharNode(n1);
list.insertCharNode(n4);
list.insertCharNode(n2);
System.out.print("Message 4 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
list.insertCharNode(n3);
list.insertCharNode(n1);
list.insertCharNode(n2);
list.insertCharNode(n4);
System.out.print("Message 5 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
CharNode n5 = new CharNode('c',2);
CharNode n6 = new CharNode('a',3);
list.insertCharNode(n1);
list.insertCharNode(n4);
list.insertCharNode(n6);
list.insertCharNode(n2);
list.insertCharNode(n5);
System.out.print("Message 6 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
list = new ListCharNodes();
n5 = new CharNode('c',2);
n6 = new CharNode('b',3);
list.insertCharNode(n1);
list.insertCharNode(n4);
list.insertCharNode(n6);
list.insertCharNode(n2);
list.insertCharNode(n5);
System.out.print("Message 7 ");
list.printMessage();
System.out.println(" is interesting or not "+ list.isPalindrome());
}
}