Java 无法解析或不是字段错误
我试图在对象的数组列表中搜索ID代码,但我被卡住了Java 无法解析或不是字段错误,java,object,arraylist,Java,Object,Arraylist,我试图在对象的数组列表中搜索ID代码,但我被卡住了 import java.util.Scanner; import java.util.ArrayList; public class Homework01{ public static void main(String[] args){ ArrayList<Transaction> argList = new ArrayList<Transaction>(); Scanner inp
import java.util.Scanner;
import java.util.ArrayList;
public class Homework01{
public static void main(String[] args){
ArrayList<Transaction> argList = new ArrayList<Transaction>();
Scanner input = new Scanner(System.in);
System.out.println("Transaction List Menu");
System.out.println("=====================");
System.out.println("1) Add Transaction.");
System.out.println("2) Search Transactions.");
System.out.println("3) Filter.");
System.out.println("4) Display All Transactions.");
System.out.println("5) Exit.");
int menu = input.nextInt();
while (menu != 5) {
switch (menu) {
case 1:
addTransaction(argList);
break;
case 2:
;// Search Transaction
break;
case 3:
;// Filter Withdraws and Deposits
break;
case 4:
;// Display transactions
break;
case 5:
System.out.println("End");
break;
default:
System.out.println("Invalid response");
break;
}
menu = input.nextInt();
}
}
public static void addTransaction(ArrayList<Transaction> argList) {
Scanner input = new Scanner(System.in);
int tempId;
double tempAmount;
char tempType;
String tempDescription;
System.out.println("Enter in an ID for the transaction: ");
tempId = input.nextInt();
System.out.println("Enter in the amount of money: ");
tempAmount = input.nextDouble();
System.out.println("W for withdraw, D for deposit: ");
tempType = input.next(".").charAt(0);
System.out.println("Give transaction a description: ");
tempDescription = input.next();
//add transaction
argList.add(new Transaction(tempId, tempAmount, tempType, tempDescription) ); }
public static void searchTransactions(ArrayList<Transaction> argList){
Scanner input = new Scanner(System.in);
System.out.println("Please type in transaction ID: ");
int searchId = input.nextInt();
for(int i=0;i<argList.size();i++){
if(argList.argId.get(i).contains(searchId)){
System.out.println("Yes");
}
}
}
}
我得到了错误消息:argId无法解析或者不是第58行的字段。我认为我的错误是argId不是ArrayList的一部分,我需要找到正确的tern来搜索ArrayList中的ID代码
谢谢ArgId是列表中对象的属性,而不是列表本身的属性,这就是为什么编译器会给您一个错误。看起来像是输入错误: 你有: argList.argId.geti.containssearchId 尝试使用: argList.geti.argId.containsSearchd argList是一个集合,然后获取对象,读取argId并检查它是否包含searchId 我建议封装类事务:
public class Transaction {
private int id;
private char type;
private double amount;
private String description;
public Transaction(int argId, double argAmount, char argType, String argDescription) {
id = argId;
type = argType;
amount = argAmount;
description = argDescription;
}
public int getId() {
return id;
}
public char getType() {
return type;
}
public double getAmount() {
return amount;
}
public String getDescription() {
return description;
}
}
然后主类将以以下方式进行查看:
import java.util.Scanner;
import java.util.ArrayList;
public class Homework01{
public static void main(String[] args){
ArrayList<Transaction> argList = new ArrayList<Transaction>();
Scanner input = new Scanner(System.in);
System.out.println("Transaction List Menu");
System.out.println("=====================");
System.out.println("1) Add Transaction.");
System.out.println("2) Search Transactions.");
System.out.println("3) Filter.");
System.out.println("4) Display All Transactions.");
System.out.println("5) Exit.");
int menu = input.nextInt();
while (menu != 5) {
switch (menu) {
case 1: ; addTransaction(argList);
break;
case 2: ;// Search Transaction
break;
case 3: ;// Filter Withdraws and Deposits
break;
case 4: ;// Display transactions
break;
case 5: System.out.println("End");
break;
default: System.out.println("Invalid response");
break;
}
menu = input.nextInt();
}
}
public static void addTransaction(ArrayList<Transaction> argList) {
Scanner input = new Scanner(System.in);
int tempId;
double tempAmount;
char tempType;
String tempDescription;
System.out.println("Enter in an ID for the transaction: ");
tempId = input.nextInt();
System.out.println("Enter in the amount of money: ");
tempAmount = input.nextDouble();
System.out.println("W for withdraw, D for deposit: ");
tempType = input.next(".").charAt(0);
System.out.println("Give transaction a description: ");
tempDescription = input.next();
//add transaction
argList.add(new Transaction(tempId, tempAmount, tempType, tempDescription)
);
}
public static void searchTransactions(ArrayList<Transaction> argList){
Scanner input = new Scanner(System.in);
System.out.println("Please type in transaction ID: ");
int searchId = input.nextInt();
for(int i=0;i<argList.size();i++){
if(argList.get(i).getId()==searchId){
System.out.println("Yes");
}
}
}
for (int i = 0; i < argList.size(); i++) {
if(argList.get(i).getId() == searchId){
System.out.println("Yes");
break;
}
}
}之前,在编辑问题之前,您使用了错误的getter方法。 而不是
public void getId(int id){
}
你应该这样写:
public int getId() {
return id;
}
将事务类中的字段声明为private。
然后以类似的方式更改其他getter
关于您的实际问题,您可以为每个循环使用:
public static void searchTransactions(ArrayList<Transaction> argList) {
try (Scanner input = new Scanner(System.in)) {
System.out.println("Please type in transaction ID: ");
int searchId = input.nextInt();
for (Transaction transaction : argList) {
if (transaction.getId() == searchId) {
System.out.println("Yes");
break;
}
}
}
}
如果您坚持使用i循环,请按以下方式进行更改:
import java.util.Scanner;
import java.util.ArrayList;
public class Homework01{
public static void main(String[] args){
ArrayList<Transaction> argList = new ArrayList<Transaction>();
Scanner input = new Scanner(System.in);
System.out.println("Transaction List Menu");
System.out.println("=====================");
System.out.println("1) Add Transaction.");
System.out.println("2) Search Transactions.");
System.out.println("3) Filter.");
System.out.println("4) Display All Transactions.");
System.out.println("5) Exit.");
int menu = input.nextInt();
while (menu != 5) {
switch (menu) {
case 1: ; addTransaction(argList);
break;
case 2: ;// Search Transaction
break;
case 3: ;// Filter Withdraws and Deposits
break;
case 4: ;// Display transactions
break;
case 5: System.out.println("End");
break;
default: System.out.println("Invalid response");
break;
}
menu = input.nextInt();
}
}
public static void addTransaction(ArrayList<Transaction> argList) {
Scanner input = new Scanner(System.in);
int tempId;
double tempAmount;
char tempType;
String tempDescription;
System.out.println("Enter in an ID for the transaction: ");
tempId = input.nextInt();
System.out.println("Enter in the amount of money: ");
tempAmount = input.nextDouble();
System.out.println("W for withdraw, D for deposit: ");
tempType = input.next(".").charAt(0);
System.out.println("Give transaction a description: ");
tempDescription = input.next();
//add transaction
argList.add(new Transaction(tempId, tempAmount, tempType, tempDescription)
);
}
public static void searchTransactions(ArrayList<Transaction> argList){
Scanner input = new Scanner(System.in);
System.out.println("Please type in transaction ID: ");
int searchId = input.nextInt();
for(int i=0;i<argList.size();i++){
if(argList.get(i).getId()==searchId){
System.out.println("Yes");
}
}
}
for (int i = 0; i < argList.size(); i++) {
if(argList.get(i).getId() == searchId){
System.out.println("Yes");
break;
}
}
所以,若argId是对象的属性,而不是列表的属性,那个么我不就在那个地方使用id吗?我试过了,但没用。放在那个位置的合适术语是什么?您必须首先从列表argList中选择一个元素:argList.getiNext point,您的方法声明特别是getter方法很奇怪,它们返回void并有一个参数-这对setter方法更有意义…argList.geti.containsserchid也是一个错误。如果目标是经常按ID查找对象,我建议也使用HashMap。事务类没有名为argId的字段,有一个字段id,其值是从构造函数中的argID设置的。