我必须检查链接列表中是否存在元素?我写了下面的代码,但它没有返回正确的输出。我无法找到我做错了什么。任何人都可以告诉我在下面的代码中做错了什么?预期输出为false且为true,但我得到的输出为false和false。
package BasicList1;
import java.util.Vector;
public class BasicList1 implements ListInterface{
static String[] testcase1 = {"3","1","2","6","7","4","5"};
public static void main (String[] args){
BasicList1 testInstance = new BasicList1();
ListNode head = new ListNode(testcase1[0]);
ListNode node = head;
System.out.println(testInstance.elements(head));
System.out.println(testInstance.hasElement(head, "9"));
System.out.println(testInstance.hasElement(head,"4"));
}
public BasicList1 getBasicList(String data){
return this;
}
//write your code here
public Vector<String> elements(ListNode head){
ListNode temp=head;
Vector v=new Vector();
while(temp!=null){
v.addElement(temp);
temp=temp.next;
}
return v;
}
@Override
public boolean hasElement(ListNode head, String data) {
ListNode temp=head;
while(temp!=null){
if(temp.data.equals(data)){
return true;
}
temp=temp.next;
}
return false;
}
答案 0 :(得分:0)
我不知道你输错的是什么,但我猜你的ListNode
只包含一个元素:3。
这只会创建一个ListNode
,其中包含一个包含testcase1[0]
的节点("3"
):
ListNode head = new ListNode(testcase1[0]);
因此,要初始化ListNode
,您应该写出类似的内容:
ListNode head = new ListNode(testcase1[testcase1.length - 1]);
for (int i = testcase1.length - 2; i >= 0; i--) {
final ListNode tail = head;
head = new ListNode(testcase1[i]);
head.next = tail;
}
NodeList
以相反的顺序构建,以避免遍历整个列表以在最后添加元素。
修改强>
您的elements
方法中也存在问题。您正在添加ListNode
而不是其内容,因此请替换
v.addElement(temp);
与
v.addElement(temp.data);
编辑2
此外,BasicList1
设计非常糟糕:它不是真正的面向对象。你应该有这样的东西:
package test;
import java.util.Vector;
public class BasicList1 {
private ListNode head;
public BasicList1(String[] data) {
if (data.length != 0 ) {
head = new ListNode(data[data.length - 1]);
}
for (int i = data.length - 2; i >= 0; i--) {
final ListNode tail = head;
head = new ListNode(data[i]);
head.next = tail;
}
}
public BasicList1 getBasicList() {
return this;
}
//write your code here
public Vector<String> elements(){
ListNode temp = head;
Vector<String> v=new Vector<String>();
while(temp!=null){
v.addElement(temp.data);
temp=temp.next;
}
return v;
}
@Override
public boolean hasElement(String data) {
ListNode temp=head;
while(temp!=null){
if(temp.data.equals(data)){
return true;
}
temp=temp.next;
}
return false;
}
public static void main (String[] args){
final String[] testcase1 = {"3","1","2","6","7","4","5"};
final BasicList1 testInstance = new BasicList1(testcase1);
System.out.println(testInstance.elements());
System.out.println(testInstance.hasElement("9"));
System.out.println(testInstance.hasElement("4"));
}
}