我写了一个java程序，允许用户将汽车数据输入到数组中。他们还可以选择更新该数据或将其删除，只有这两个功能不起作用。我一直在努力解决这个问题，非常感谢任何帮助。最后我还尝试将所有数据写入txt文件，我认为这样做正常。
再次感谢您提供任何帮助！
package portfolio_johnhuber;
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Automobile {
private String make;
private String model;
private String color;
private int year;
private int mileage;
//Here we will create a new automobile
public Automobile(String make, String model, String color, int year, int
mileage){
this.make = make;
this.model = model;
this.color = color;
this.year = year;
this.mileage = mileage;
}
//Here we create access to the make property
public String getMake(){
return make;
}
//Here we create access to the model property
public String getModel(){
return model;
}
////Here we create access to the color property
public String getColor(){
return color;
}
//Here we create access to the year property
public int getyear(){
return year;
}
//Here we create access to the mileage property
public int getMileage(){
return mileage;
}
//Here we need to update the make property
public void setMake(String make){
this.make = make;
}
//Here we need to update the model property
public void setModel(String model){
this.model = model;
}
//Here we need to update the color property
public void setColor(String color){
this.color = color;
}
//Here we need to update the year property
public void setYear(int year){
this.year = year;
}
//Here we need to update the mileage property
public void setMileage(int mileage){
this.mileage = mileage;
}
//Not sure if this will work, String for printing as text
@Override
public String toString(){
return "Automobile(" + "make=" + make + ", model=" + model + ", color="
+ color + ", year=" + year + ",mileage=" + mileage +'}';
}
//this is where the program hopefully manages the automobiles
public static void main(String[] args) throws Exception{
List<Automobile> autos = new ArrayList<>();
Scanner in = new Scanner (System.in);
//Menu is displayed for user
while (true){
System.out.println("Welcome to the vehicle inventory program, please
make your selection");
System.out.println("1. Add a vehicle");
System.out.println("2. Remove a vehicle");
System.out.println("3. Update a vehicle");
System.out.println("0. Exit");
//Option selection
System.out.println("Option: ");
int option = Integer.parseInt(in.nextLine());
//Process user selected option
if (option == 1){
//Add new vehicle option
System.out.println("Make: ");
String make = in.nextLine();
System.out.println("Model: ");
String model = in.nextLine();
System.out.println("Color: ");
String color = in.nextLine();
System.out.println("Year: ");
int year = Integer.parseInt(in.nextLine());
System.out.println("Mileage: ");
int mileage = Integer.parseInt(in.nextLine());
Automobile auto = new Automobile
(make, model, color, year, mileage);
autos.add(auto);
System.out.println("Vehicle added!");
}
else if (option == 2 || option == 3){
//user can select vehicle
System.out.println("Please select a vehicle");
for (int i = 0; i < autos.size(); i++){
System.out.println(i + " - " + autos.get(i));
}
System.out.print("Option: ");
option = Integer.parseInt(in.nextLine());
if (option < 0 || option >= autos.size()){
//confirm selected vehicle
System.out.println("Invalid Selection");
}
else if (option == 2){
//delete the selected vehicle
Automobile auto = autos.remove(option);
System.out.println("Removed - " + auto);
}
else if (option == 3){
//update the selected vehcile
Automobile auto = autos.remove(option);
System.out.println("Updated Vehicle - " + auto);
System.out.print("Make: ");
auto.setMake(in.nextLine());
System.out.print("Model: ");
auto.setModel(in.nextLine());
System.out.print("Color: ");
auto.setColor(in.nextLine());
System.out.print("Year: ");
auto.setYear(Integer.parseInt(in.nextLine()));
System.out.print("Mileage: ");
auto.setMileage(Integer.parseInt(in.nextLine()));
System.out.println("Your vehicle is updated!");
}
}
else if (option == 0){
//Exit the program
break;
}
}
//write the vehicles to a file
PrintWriter outFile = new PrintWriter(new FileWriter("vehcles.txt"));
for (Automobile auto : autos){
outFile.println(auto);
}
outFile.close();
System.out.println("All Vehicle data has been written to vehicles.txt");
}
}
答案 0 :(得分：0)
如果要删除或更新自动，则使用选项，但这不是数组索引。因此，在删除或更新时，您应该在代码中 selectedVehicle 。试试这个：
import java.io.FileWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Automobile {
private String make;
private String model;
private String color;
private int year;
private int mileage;
//Here we will create a new automobile
public Automobile(String make, String model, String color, int year, int
mileage){
this.make = make;
this.model = model;
this.color = color;
this.year = year;
this.mileage = mileage;
}
//Here we create access to the make property
public String getMake(){
return make;
}
//Here we create access to the model property
public String getModel(){
return model;
}
////Here we create access to the color property
public String getColor(){
return color;
}
//Here we create access to the year property
public int getyear(){
return year;
}
//Here we create access to the mileage property
public int getMileage(){
return mileage;
}
//Here we need to update the make property
public void setMake(String make){
this.make = make;
}
//Here we need to update the model property
public void setModel(String model){
this.model = model;
}
//Here we need to update the color property
public void setColor(String color){
this.color = color;
}
//Here we need to update the year property
public void setYear(int year){
this.year = year;
}
//Here we need to update the mileage property
public void setMileage(int mileage){
this.mileage = mileage;
}
//Not sure if this will work, String for printing as text
@Override
public String toString(){
return "Automobile(" + "make=" + make + ", model=" + model + ", color="
+ color + ", year=" + year + ",mileage=" + mileage +'}';
}
//this is where the program hopefully manages the automobiles
public static void main(String[] args) throws Exception{
List<Automobile> autos = new ArrayList<>();
Scanner in = new Scanner (System.in);
//Menu is displayed for user
while (true){
System.out.println("Welcome to the vehicle inventory program, please make your selection");
System.out.println("1. Add a vehicle");
System.out.println("2. Remove a vehicle");
System.out.println("3. Update a vehicle");
System.out.println("0. Exit");
//Option selection
System.out.println("Option: ");
int option = Integer.parseInt(in.nextLine());
//Process user selected option
if (option == 1){
//Add new vehicle option
System.out.println("Make: ");
String make = in.nextLine();
System.out.println("Model: ");
String model = in.nextLine();
System.out.println("Color: ");
String color = in.nextLine();
System.out.println("Year: ");
int year = Integer.parseInt(in.nextLine());
System.out.println("Mileage: ");
int mileage = Integer.parseInt(in.nextLine());
Automobile auto = new Automobile
(make, model, color, year, mileage);
autos.add(auto);
System.out.println("Vehicle added!");
}
else if (option == 2 || option == 3){
//user can select vehicle
System.out.println("Please select a vehicle");
for (int i = 0; i < autos.size(); i++){
System.out.println(i + " - " + autos.get(i));
}
System.out.print("Option: ");
int selectVehicle = Integer.parseInt(in.nextLine());
if (selectVehicle < 0 || selectVehicle >= autos.size()){
//confirm selected vehicle
System.out.println("Invalid Selection");
}
else if (option == 2){
//delete the selected vehicle
Automobile auto = autos.remove(selectVehicle);
System.out.println("Removed - " + auto);
}
else if (option == 3){
//update the selected vehcile
Automobile auto = autos.get(selectVehicle);
System.out.println("Updated Vehicle - " + auto);
System.out.print("Make: ");
auto.setMake(in.nextLine());
System.out.print("Model: ");
auto.setModel(in.nextLine());
System.out.print("Color: ");
auto.setColor(in.nextLine());
System.out.print("Year: ");
auto.setYear(Integer.parseInt(in.nextLine()));
System.out.print("Mileage: ");
auto.setMileage(Integer.parseInt(in.nextLine()));
System.out.println("Your vehicle is updated!");
}
}
else if (option == 0){
//Exit the program
break;
}
}
//write the vehicles to a file
PrintWriter outFile = new PrintWriter(new FileWriter("vehcles.txt"));
for (Automobile auto : autos){
outFile.println(auto);
}
outFile.close();
System.out.println("All Vehicle data has been written to vehicles.txt");
}
}
答案 1 :(得分：0)
您正在重复使用变量options来获取选项的输入以及所选汽车的索引。您应该使用其他变量。
System.out.print("Option: ");
int index = Integer.parseInt(in.nextLine());
if (index < 0 || index >= autos.size()){
//confirm selected vehicle
System.out.println("Invalid Selection");
}
else if (option == 2){
//delete the selected vehicle
Automobile auto = autos.remove(index);
System.out.println("Removed - " + auto);
}
else if (option == 3){
//edit
}