我正在编写程序；有卡车级，车辆级，人员级和驾驶员级。
卡车和车辆用于向车辆设置信息，人员用于设置人员信息，驾驶员全部运行。
我当前的问题是我正在尝试使用try catch语句来检查用户输入的数据与上一次输入的数据相同，但似乎无法正确输入。
我将在下面附加我的所有课程，虽然很冗长，但希望会有所帮助。
//driver class
import java.util.Scanner;
import java.util.InputMismatchException;
public class Driver{
public static void main(String args[]){
Scanner keyboard= new Scanner(System.in);
//creates vehicles
Vehicle car1= new Vehicle();
Vehicle car2= new Vehicle();
Vehicle car3= new Vehicle();
//creates trucks
Truck truck1= new Truck();
Truck truck2= new Truck();
Truck truck3= new Truck();
boolean check1=true;
boolean check2=true;
boolean check3=true;
boolean nameCheck=false;
boolean truckCheck1=false;
boolean truckCheck2=false;
boolean truckCheck3=false;
while(!nameCheck) {
System.out.println("Enter first persons name");
Person owner1 = new Person(keyboard.next()); // creates new person
car1.setOwner(owner1); //makes the first person the owner of the first car
if (car1.equals(car1)) //checking if name is null
nameCheck=true;
}
System.out.println("You entered: " + car1.getOwner()); //echoes user input
System.out.println("Enter manufacturer of car 1");
car1.setManufacturer(keyboard.next()); //set manufacturer of car 1
System.out.println("You entered: " + car1.getManufacturer() + " as car 1 manufacturer");
while( check1 && nameCheck){
try //data check
{
System.out.println("Enter number of cylinders for car 1");
car1.setCylinders(keyboard.nextInt());
if (car1.cylinders<2 || car1.cylinders>30)
throw new Exception("You entered an invalid amount of cylidners!");
else
check1=false;
System.out.println(car1.toString());
}
catch (InputMismatchException e){
keyboard.next();
System.out.println("Cylinders must be entered in integer form");
System.out.println("Try again!");
}
catch (Exception e){
String message = e.getMessage();
System.out.println(message);
}
}
while (!check1){
System.out.println("Please set name, car manufacturer, and cylinders equal to car 1");
try{
System.out.println("Enter second persons name");
Person owner2 = new Person (keyboard.next());
car2.setOwner(owner2);
if (!car2.getOwner().equals(car1.getOwner()))
throw new Exception("Invalid name entered, please enter same name as owner 1");
else
check1=true;
}
catch(Exception e){
keyboard.next();
System.out.println("Please enter same owner as car 1");
System.out.println("Try again!");
}
System.out.println("You entered: " + car2.getOwner());
check1=true;
System.out.println("Enter manufacturer of car 2");
car2.setManufacturer(keyboard.next());
System.out.println("You entered: " + car2.getManufacturer());
while (nameCheck) {
try {
System.out.println("Enter number of cylinders for the second vehicle");
car2.setCylinders(keyboard.nextInt());
if (car2.cylinders< 2 || car2.cylinders>30)
throw new Exception("You entered an invalid amount of cylinders!");
else
check2= false;
System.out.println(car2.toString());
}
catch(InputMismatchException e) {
keyboard.next();
System.out.println("Cylinders must be entered a as an integer between 2 and 30");
System.out.println("Try again!");
} catch (Exception e){
String message= e.getMessage();
System.out.println(message);
}
}
}
while (!check2) {
System.out.println("Enter third persons name");
Person owner3= new Person(keyboard.next());
car3.setOwner(owner3);
System.out.println("You entered: " + owner3);
System.out.println("Enter manufacturer of car 3");
car3.setManufacturer(keyboard.next());
System.out.println("You entered: " + car3.getManufacturer());
while (check3) {
try {
System.out.println("Enter number of cylinders for car 3");
car3.setCylinders(keyboard.nextInt());
if (car3.cylinders<2 || car3.cylinders>30)
throw new Exception("Invalid amount of cylinder entered!");
else
check2=true;
check3=false;
check1=false;
System.out.println(car3.toString());
} catch (InputMismatchException e) {
keyboard.next();
System.out.println("Cylinders must be entered a as an integer between 2 and 30");
System.out.println("Try again!");
} catch (Exception e) {
String message= e.getMessage();
System.out.println(message);
}
}
}
truck1.setOwner(car1.getOwner()); //sets owner of car1 to truck1
System.out.println("Enter manufacturer of truck 1, Owner will be the same as car 1");
truck1.setManufacturer(keyboard.next());
System.out.println("You entered: " + truck1.getManufacturer());
while (!truckCheck1)
try {
System.out.println("Enter cyliners for truck 1");
truck1.setCylinders(keyboard.nextInt());
if (truck1.cylinders<2 || truck1.cylinders>30)
throw new Exception("Invalid amount of cylinders entered!");
else
truckCheck1= true;
} catch (InputMismatchException e) {
keyboard.nextInt();
System.out.println("Cylinders must be entered a as an integer between 2 and 30");
System.out.println("Try again!");
} catch (Exception e) {
String message= e.getMessage();
System.out.println(message);
}
System.out.println("You entered: " + truck1.getCylinders());
while (truckCheck1)
try {
System.out.println("Enter load capacity in tons for truck 1. Must be greater than zero");
truck1.setLoadCapacity(keyboard.nextDouble());
if (truck1.getLoadCapacity()<0)
throw new Exception("You entered an invalid load capacity");
else
truckCheck1= false;
} catch(InputMismatchException e) {
keyboard.next();
System.out.println("Load capacity must be in integer format");
System.out.println("Try again!");
} catch (Exception e) {
String message= e.getMessage();
System.out.println(message);
}
System.out.println("You entered: " + truck1.getLoadCapacity());
while (!truckCheck1)
try {
System.out.println("Enter towing capacity in pounds of truck 1");
truck1.setTowCapacity(keyboard.nextInt());
if (truck1.getTowCapacity()<0)
throw new Exception("You entered an invalid tow capacity, tow capacity must be entered as an integer");
else
truckCheck1= true;
}catch (InputMismatchException e){
keyboard.next();
System.out.println("Towing Capacity must be in integer form");
System.out.println("Try again!");
} catch (Exception e){
String message= e.getMessage();
System.out.println(message);
}
System.out.println(truck1);
truck2.setOwner(car2.getOwner()); //sets truck 2 owner the same as car 2 owner
System.out.println("Enter manufacturer of truck 2");
truck2.setManufacturer(keyboard.next());
System.out.println("You entered: " + truck2.getManufacturer());
while(!truckCheck2)
try {
System.out.println("Enter number of cylinders for truck 2, must be a integer between 2 and 30");
truck2.setCylinders(keyboard.nextInt());
if (truck2.cylinders<2 || truck2.cylinders>30)
throw new Exception("You entered an invalid amount of cylinders");
else
truckCheck2= true;
} catch (InputMismatchException e){
keyboard.next();
System.out.println("Load capacity must be entered as an integer");
System.out.println("Try again!");
} catch (Exception e){
String message= e.getMessage();
System.out.println(message);
}
System.out.println("You entered: " + truck2.getCylinders());
while (truckCheck2)
try{
System.out.println("Enter towing capacity in pounds of truck 2");
truck2.setLoadCapacity(keyboard.nextDouble());
if (truck2.getLoadCapacity()<0)
throw new Exception("Invalid Tow Capacity Entered");
else
truckCheck2=false;
}catch (InputMismatchException e){
keyboard.next();
System.out.println("Load Capacity must be entered as an integer");
System.out.println("Try again!");
} catch (Exception e) {
String message = e.getMessage();
System.out.println(message);
}
System.out.println("You entered: " + truck1.getLoadCapacity());
while (!truckCheck2)
try {
System.out.println("Enter Towing capacity in pounds of truck 1");
truck2.setTowCapacity(keyboard.nextInt());
if (truck2.getTowCapacity()<0)
throw new Exception("Invalid Tow Capacity Entered");
else
truckCheck2= true;
} catch (InputMismatchException e){
keyboard.next();
System.out.println("Towing Capacity must be entered as an integer");
System.out.println("Try again!");
} catch (Exception e){
String message= e.getMessage();
System.out.println(message);
}
System.out.println(truck2);
//collectin third truck info
truck3.setOwner(car3.getOwner());
System.out.println("Enter manufacturer of truck 3, Owner will be the same as car 3");
truck3.setManufacturer(keyboard.next());
System.out.println("You entered: " + truck3.getManufacturer());
while(!truckCheck3)
try{
System.out.println("Enter Cylinders of truck 3, must be a integet between 2 and 30");
truck3.setCylinders(keyboard.nextInt());
if(truck3.cylinders<2 || truck3.cylinders>30)
throw new Exception("Invalid amount of cylinders entered");
else
truckCheck3= true;
} catch (InputMismatchException e) {
keyboard.next();
System.out.println("Cylinders must be an integer");
System.out.println("Try again!");
} catch (Exception e){
String message= e.getMessage();
System.out.println(message);
}
System.out.println("You entered: " + truck3.getCylinders());
while (truckCheck3)
try {
System.out.println("Enter load capacity in tons of truck 3, must be greater than 0");
truck3.setLoadCapacity(keyboard.nextDouble());
if (truck3.getLoadCapacity()<0)
throw new Exception("Invalid amount entered");
else
truckCheck3= false;
} catch (InputMismatchException e){
keyboard.next();
System.out.println("Load capacity must be in integer form");
System.out.println("Try again!");
} catch (Exception e) {
String message= e.getMessage();
System.out.println(message);
}
System.out.println("You entered: " + truck3.getLoadCapacity());
while(!truckCheck3)
try {
System.out.println("Enter towing capacity in pounds of truck 3");
truck3.setTowCapacity(keyboard.nextInt());
if (truck3.getTowCapacity()<0)
throw new Exception("Invalud amount entered");
else
truckCheck3= true;
} catch (InputMismatchException e) {
keyboard.next();
System.out.println("Towing capacity must be in integer form");
System.out.println("Try again!");
} catch (Exception e) {
String message= e.getMessage();
System.out.println(message);
}
System.out.println();
System.out.println("Car Details:" + "\n" + "Car 1:" + car1 + "\n" + "Car 2:" + "\n" + car2 + "\n" + "Car 3:" + "\n" + car3);
System.out.println();
System.out.println("Truck Details:" + "\n" + "Truck 1:" + truck1 + "\n" + "Truck 2:" + "\n" + truck2 + "\n" + "Truck 3:" + "\n" + truck3);
}
}
/** vehicle class
Carmine */
public class Vehicle{
public String manufacturer;
public int cylinders;
public Person owner; //owner pulled from person class
public Vehicle(){
manufacturer="none";
cylinders=1;
owner=null;
}
public Vehicle(String theManufacturer, int numOfCylinders, Person theOwner)
{
theManufacturer=manufacturer;
numOfCylinders=cylinders;
owner=new Person(theOwner);
}
//sets manufacturer
public void setManufacturer(String newManufacturer){
manufacturer=newManufacturer;
}
//return manufacturer name
public String getManufacturer(){
return manufacturer;
}
//sets cylinders
public void setCylinders(int numOfCylinders){
cylinders=numOfCylinders;
}
//return cylinders
public int getCylinders(){
return cylinders;
}
//sets owner
public void setOwner(Person newOwner)
{
owner = new Person(newOwner);
}
//returns owner
public Person getOwner(){
return owner;
}
@Override
public String toString(){
return ("Manufaturer: " + manufacturer + "\n" + "Cylinders: " + cylinders + "\n" + "Owner: " + owner);
}
}
//Person Class
public class Person {
private String name;
public Person()
{
name = "none";
}
public Person(String theName) {
name = theName;
}
public Person(Person theObject) {
name = theObject.name;
}
public String getName() {
return name;
}
public void setName(String theName) {
name = theName;
}
public String toString() {
return name;
}
public boolean equals(Object other) {
return name.equals(((Person) other).name);
}
}
public class Truck extends Vehicle //entends truck from vehicle
{
double loadCapacity;
int towCapacity;
public Truck(){
super();
loadCapacity=0;
towCapacity=0;
}
public Truck(String m, int c, Person p, double load, int capacity){
super(m,c,p);
loadCapacity=load;
towCapacity=capacity;
}
//sets load
public void setLoadCapacity(double newLoad){
loadCapacity=newLoad;
}
//returns load
public double getLoadCapacity(){
return loadCapacity;
}
//sets towCapacity
public void setTowCapacity(int newCapacity){
towCapacity=newCapacity;
}
//return towCapacity
public int getTowCapacity(){
return towCapacity;
}
public String toString()
{
return super.toString() + ("Load Capacity: " + loadCapacity + "\n" + "Tow Capacity: " + towCapacity);
}
}
我知道很多代码，但是这个try catch语句确实使我感到沮丧，我只想完成此操作。
在这种情况下，我还需要使用.equals来检查是否相等。两个人必须和两个卡车和小汽车一样。
答案 0 :(得分：1)
当您的检查失败时，您的代码将抛出Exception，而不是InputMismatchException。因此，不会打印“重试”的输出。
我对使用异常一开始有些困惑。当您知道存在问题时，为什么不直接在if块中处理问题，因为所有问题都包含在while循环中，直到输入正确为止。
异常通常在非常特殊的情况下使用，例如系统错误或意外事件。在大多数情况下，如果您可以在从用户那里获得输入后立即检查输入，则代码可以像在循环中那样立即处理输入是否有效。