根据之前的 ELEMENTS 递增 ArrayElement 参数

Question

我是 java 新手，但一直在玩数组列表，现在卡住了。

我从一个名为 Car 的类中创建了一个数组列表，其中包含三个参数，其中一个称为timesmoved。

主班

public class GarageTester {

/**

 * @param args the command line arguments

 */

  public static void main(String[] args) throws IOException{

   // create Bank object

   Garage bashimGarage = new Garage() ;

  // create Scanner object associated with input file

  Scanner fileScan = new Scanner(new 

   File("C:\\Users\\jamison\\Desktop\\GarageData.txt")) ;

  // read BankAccount data from file, create objects, and add to list

   while ( fileScan.hasNextLine())      // while not eof

   {

     String fullText = fileScan.nextLine();

     // Split the acquired string into 2 based on the whitespace

     String[] splitText = fullText.split("\\s+");

     // String before whitespace split

     String licensePlate = splitText[0];

     // String after whitespace split

     String status = splitText[1];

     // create Car object

     Car newCar = new Car(licensePlate, status , 0) ;  

     // add to list   

     bashimGarage.addCar( newCar ) ;   

   }

  /*

    *Calculates the number of times car was temporary moved before departure

  */

  bashimGarage.carDepart();

  /*

    *Prints list of car license plates

    * Admits or declines a car to the garage

    * Prints if a car departs the Garage

    * When a car departs also prints the number of times it was moved

  */

   bashimGarage.moveCarInGarage();

车类

public class Car {

   private String licensePlate;    // License Plate Number

   private String status ;         // Status: Arivved or Departed

   private int moved;              /* How many times the car 

                                  got moved out of the garage

                                  */

public Car ( String licenseNum, String carStatus , int timesMoved)

 {   

    licensePlate = licenseNum ;

    status = carStatus ;

    moved = timesMoved;

 }

public String getLicenseNum()

{   

  return licensePlate;

}

public String getStatus()

{   

  return status;

}

 public int getTimesMoved()

{   

  return moved;

}

Answer 1

第一种方法，第 8 行。为什么要pos在i. int pos = list.indexOf(i);会给-1。另外，在这个循环中for ( int j = 0 ; pos < j ; j++)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; current.setTimesMoved(1 + current.getTimesMoved());&nbsp; &nbsp; }你总是指向数组列表中的同一个元素。相反，您可能希望像下面这样对其进行编程：for ( int j = 0; j<i; j++)&nbsp; &nbsp; {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Car car = list.get(j);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; car.setTimesMoved(1 + car.getTimesMoved());&nbsp; &nbsp; }

Answer 2

您的方法中有以下问题，首先你得到一个整数而不是对象的索引。您的内部 for 循环条件是错误的。您总是增加当前对象的值而不是以前的值。我已经用你的方法纠正了它们。使用以下一种，public void carDepart() {&nbsp; &nbsp; &nbsp; &nbsp; for (int i = 0; i < list.size(); i++) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Car current = list.get(i);&nbsp; &nbsp;// get next car&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; if (current.getStatus().equals("DEPART")) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; /* You can remove below line and replace pos with i in your inner loop.&nbsp;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; Since the current object position will be same as i */&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; int pos = list.indexOf(current);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for (int j = 0; j < pos; j++) {&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; list.get(j).setTimesMoved(1 + current.getTimesMoved());&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; list.remove(i);&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; return;&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; &nbsp; &nbsp; }&nbsp; &nbsp; }