我成功制作了一个链表，但现在我无法处理它。我需要将哪些方法添加到我的FoodList类才能处理我的对象？例如，我需要让用户能够选择手动添加食物对象，这样我就可以打印一顿饭了。另外，我不能使用java API中的任何集合类。这一切都必须是定制的。
public static void main(String[] args) {
FoodList list = new FoodList();
boolean keepGoing = true;
int scanResultInt;
try
{
//I/O stream
FileReader fr = new FileReader("foodlist.txt");
BufferedReader br = new BufferedReader(fr);
Scanner scan = new Scanner(br);
Food hold = new Food();
while(scan.hasNext()){
list.add(hold = new Food());
String str = scan.next();
//str = scan.next();
hold.setName(str);
str = scan.next();
hold.setGroup(str);
int cal = scan.nextInt();
hold.setNumCal(cal);
double percent = scan.nextDouble();
hold.setPercentDV(percent);
list.add(hold);
}
//System.out.println("" + list.toString());
br.close(); //close I/O stream
}
catch(IOException e){
System.err.println("I/O EXCEPTION: " + e.getMessage());
}
Scanner scan2 = new Scanner(System.in);
do {
System.out.println("---------------------------------------------------------");
System.out.println(" Welcome to the Parkland Meal Selector" );
System.out.println("---------------------------------------------------------");
System.out.println("Enter the number of the menu option you would like to select:");
System.out.println(" 1) List food database");
System.out.println(" 2) Create meal by manual selection");
System.out.println(" 3) Create meal by random selection");
System.out.println(" 4) Remove foods high in calories");
System.out.println(" 5) Exit");
scanResultInt = scan2.nextInt();
switch(scanResultInt) {
case 1: {
System.out.println("" + list.toString());
break;
}
case 2: {
System.out.println("Create-A-Meal Menu\n");
System.out.println("Enter the name of a food you would like to add:\n");
String foodWanted = scan2.next();
/*while( != null){
if(foodWanted.equals());
}*/
/*Food tmp;
for(tmp = head; tmp != null; tmp = tmp.next)
{
result += tmp.f;
}
return result;*/
}
case 3: {
System.out.println("Create meal by random selection: \n");
break;
}
case 4: {
System.out.println("Remove Food High In Calories: \n");
break;
}
case 5: {
keepGoing = false;
break;
}
}
}
while(keepGoing);
}
这是我的链接列表：
public class FoodList {
// Class fields
private FoodNode head;
private int listCount;
// Private inner class
private class FoodNode
{
public Food f;
public FoodNode next;
public FoodNode(Food f)
{
this.f = f;
this.next = null;
}
}
// Constructor for LinkedList
public FoodList()
{
// Initialize start of the list
head = null;
listCount = 0;
}
// Add method (adds a reservation to the linked list)
public void add(Food f)
{
// Create a new ReservationNode
FoodNode node = new FoodNode(f);
// If this is the first node
if( head == null )
head = node;
else
{
FoodNode tmp = head;
while(tmp.next != null)
tmp = tmp.next;
tmp.next = node;
}
listCount++
}
/*public boolean hasThatFood(String food){
boolean haveThat = false;
FoodNode tmp;
for(tmp = head; tmp != null; tmp = tmp.next)
{
if (food == f.getName());
haveThat = true;
}
return haveThat;
}*/
/*public boolean hasNext(){
boolean hasNext = false;
if(head != null) {
hasNext = true;
return hasNext;
}
}*/
@Override
public String toString() {
String result = "My Foods:" + '\n';
// Loop through all the reservation nodes
FoodNode tmp;
for(tmp = head; tmp != null; tmp = tmp.next)
{
result += tmp.f;
}
return result;
}
}
我的食物课
public class Food {
private String name;
private String group;
private int numCal;
private double percentDV;
public Food() {//String name, String group, int numCal, double percentDV
/*this.name = name;
this.group = group;
this.numCal = numCal;
this.percentDV = percentDV;*/
name = "";
group = "";
numCal = 0;
percentDV = 0.0;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getGroup() {
return group;
}
public void setGroup(String group) {
this.group = group;
}
public int getNumCal() {
return numCal;
}
public void setNumCal(int numCal) {
this.numCal = numCal;
}
public double getPercentDV() {
return percentDV;
}
public void setPercentDV(double percentDV) {
this.percentDV = percentDV;
}
@Override
public String toString() {
return "Food{" +
"name: '" + name + '\'' +
", Food Group: '" + group + '\'' +
", Calories: " + numCal +
", Daily Percent: " + percentDV +
'}';
}
}
我知道这是意大利面条代码，但这是我的最后手段。任何帮助都会受到欢迎！
答案 0 :(得分：1)
要操作对象，您必须编写自定义Iterator。我想这里打开LinkedList来源并了解其工作原理并不是犯罪行为。
答案 1 :(得分：1)
像这样的东西，你可以在网上找到很多资源，
https://crunchify.com/how-to-implement-a-linkedlist-class-from-scratch-in-java/
这是一个。
(lldb) expr -l objc -O -- 0x7fc795700140
<UIApplication: 0x7fc795700140>
答案 2 :(得分：1)
您已经实现了一些复杂的类。它的内在逻辑不像你的问题那么清楚。因此，几乎任何答案都无法满足您的需求。
如果我愿意，我会尝试使用java核心工具推荐逻辑（不实现以最佳方式实现的类LinkedList，ArrayList ...）。逻辑应转换为一些结构解决方案。例如：
如果你以更加结构化的方式提供逻辑，你会问更明确的问题指出问题。此外，我相信你的问题将在准备之后消失。
我还建议您熟悉下一个GoF patterns：builder，factory method，composite，strategy。