如何在对象链列表中搜索特定字段?

Question

我正在编写一个程序，将我的类"TeamRecord"的对象存储到链表中。我在使搜索方法正常工作时遇到问题。下面的代码适用于仅包含字符串的链表，但由于这是TeamRecord对象的链接列表，我需要弄清楚如何仅查看团队名称字段。

调用搜索方法：

case 5:     
System.out.println("Enter team name to search: ");
String input = console.next();
if(teams.search(input))
System.out.println(input + " is a team.");
else
System.out.println(input + " is not a team.");
break;

我收到错误，因为字符串输入无法转换为团队记录

搜索方法：

public boolean search(E element) {
if(isEmpty())
return false;
//create a new node for the element
Node<E> temp = new Node<E>(element, null);
temp = head;
while(temp != null)
{
if(temp.getElement().equals(element))
return true;
temp = temp.getNext();
}
return false; 
}

我试过这个：

if(teams.getTeamName().search(input))

但这不起作用，因为"团队"是 LinkedList 的名称，所以我实际上并没有查看单个对象。我真的不确定如何处理这个问题。任何帮助将不胜感激

我将在此处发布其余代码，以防上述内容还不够：

public class TeamRecord implements Comparable<TeamRecord>{
private String teamName;
private int totalWin;
private int totalLoss;
public TeamRecord() {
}
public TeamRecord(String teamName, int totalWin, int totalLoss) {
this.teamName = teamName;
this.totalWin = totalWin;
this.totalLoss = totalLoss;
}
public String getTeamName() {
return teamName;
}
public void setTeamName(String teamName) {
this.teamName = teamName;
}
public int getTotalWin() {
return totalWin;
}
public void setTotalWin(int totalWin) {
this.totalWin = totalWin;
}
public int getTotalLoss() {
return totalLoss;
}
public void setTotalLoss(int totalLoss) {
this.totalLoss = totalLoss;
}
public int compareTo(TeamRecord T) {
return this.teamName.compareTo(T.teamName);
}
@Override
public String toString() {
return "nnTeam Name: " + teamName + "nTotal Wins: " + totalWin + 
"nTotal Losses: " + totalLoss;
}

}

链表：

public class MyLinkedList<E> {
//data members
private Node<E> head;
private Node<E> tail;
int size;
//contructor
public MyLinkedList(){
head = null;
tail = null;
size = 0;
}
public boolean isEmpty(){
if(head == null)
return true;
return false;
}
public int size(){
return size;
}
public void addFirst(E element){
//create a new node for the element
Node<E> temp = new Node(element, null);
//if the list is empty
if(isEmpty()){
head = temp;
}
else{
//temp's next = head
temp.setNext(head);
head = temp;
}
size++;
} 
public E removeFirst() throws EmptyListException {
if(isEmpty()) 
throw new EmptyListException("This list is empty.");
Node<E> temp = head;
//move head to head next
head = head.getNext();
E result = temp.getElement();
temp.setNext(null);
temp = null;
size--;
return result;
}
public void addLast(E element) {
//create a new node for the element
Node<E> temp = new Node<E>(element, null);
if(head != null)
{
Node<E> tail = head;
while(tail.getNext() != null)
{
tail = tail.getNext();
}
tail.setNext(temp);
}
else
head = temp;
size++;
}
public boolean search(E element) {
if(isEmpty())
return false;
//create a new node for the element
Node<E> temp = new Node<E>(element, null);
temp = head;
while(temp != null)
{
if(temp.getElement().equals(element))
return true;
temp = temp.getNext();
}
return false; 
}
public String traverse(){
if(isEmpty())
return "Empty list";
String result = "Head --->";
int i = size;
Node<E> temp = head;
while(i > 0){
result += temp.getElement();
temp = temp.getNext();
i--;
}
return result;
}
}//end of class

节点类：

class Node<E> {
//data members
private E element;
private Node<E> next;
//constructors
public Node() {
this(null, null);
}
public Node(E element, Node<E> next) {
this.element = element;
this.next = next;
}
//setters and getters
public void setElement(E element) {
this.element = element;
}
public void setNext(Node<E> next) {
this.next = next;
}
public E getElement() {
return element;
}
public Node<E> getNext() {
return next;
}
}

客户：

public class TeamRecordClient {
static Scanner console = new Scanner(System.in);
public static int main(String [] args) {
MyLinkedList<TeamRecord> teams = new MyLinkedList();

boolean flag = true;
int userCommand;
while (flag) {
showMenu();
userCommand = console.nextInt();
switch (userCommand) {
//addFirst
case 1:
System.out.println("Enter Team Name: ");
String name = console.next();
System.out.println("Enter Total Wins: ");
int totalWins = console.nextInt();
System.out.println("Enter Total Losses: ");
int totalLosses = console.nextInt();
teams.addFirst(new TeamRecord(name, totalWins, totalLosses));

break;
//removeFirst
case 2:
try{
TeamRecord result = teams.removeFirst();
System.out.println("Removed Team: " + teams.toString());
}
catch(EmptyListException e) {
System.out.println(e.toString());
}
break;
//addLast
case 3:
System.out.println("Enter Team Name: ");
String name1 = console.next();
System.out.println("Enter Total Wins: ");
int totalWins1 = console.nextInt();
System.out.println("Enter Total Losses: ");
int totalLosses1 = console.nextInt();
teams.addLast(new TeamRecord(name1, totalWins1, totalLosses1));
break;
//traverse
case 4:
System.out.println(teams.traverse());
break;
//search for a element
case 5:     
System.out.println("Enter team name to search: ");
String input = console.next();
if(teams.search(input))
System.out.println(input + " is a team.");
else
System.out.println(input + " is not a team.");
break;
case 0:
flag = false;
break;
default:
}
}//end main
}     
private static void showMenu() {
System.out.print("nn"
+ "n1 - Add First"
+ "n2 - Remove First"
+ "n3 - Add Last"
+ "n4 - Traverse"
+ "n5 - Search"
+ "n6 - Selection Sort(Team Name)"
+ "n7 - Quick Sort(Total Wins)"
+ "n0 - Exit "
+ "nEnter a command: ");
}
}//end of class

Answer 1

我建议你修改你的search()方法，改用谓词：

public boolean search(Predicate<? super E> predicate) {
Node<E> temp = head;
while (temp != null) {
if (predicate.test(temp.getElement()))
return true;
temp = temp.getNext();
}
return false; 
}

然后，您可以为搜索指定任何Predicate：

if (teams.search(e -> e.getTeamName().equals(input))
System.out.println(input + " is a team.");
else
System.out.println(input + " is not a team.");