java - 如何在Java中设置默认的增量/减量值

Question

好的，我有一个家庭作业问题。我正在构建一个在我的讲师提供的测试人员类(class)中使用的类(class)。它只不过是一个基本的计数器。我已经将计数器设置为测试人员传递到我的类(class)的数字工作正常并且输出符合预期。但是，我的类必须将初始计数设置为 0，并将默认增量/减量设置为 1。

这是我的类(class):

public class Counter
{
    private int count;
    private int stepValue;

    /**
     * This method transfers the values called from CounterTester to instance variables
     * and increases/decreases by the values passed to it. It also returns the value
     * of count. 
     *
     * @param args
     */ 
    public Counter (int initCount, int value)
    {       
        count=initCount;
        stepValue=value;
    }   

    public void increase ()
    {
        count = count + stepValue;
    }

    public void decrease ()
    {
        count = count - stepValue;
    }

    public int getCount()
    {
        return count;
    }

}

这是测试器类:

public class CounterTester
{

    /**
     * This program is used to test the Counter class and does not expect any
     * command line arguments. 
     *
     * @param args
     */
    public static void main(String[] args)
    {
        Counter counter = new Counter();

        counter.increase();
        System.out.println("Expected Count: 1 -----> Actual Count: " + counter.getCount());

        counter.increase();
        System.out.println("Expected Count: 2 -----> Actual Count: " + counter.getCount());

        counter.decrease();
        System.out.println("Expected Count: 1 -----> Actual Count: " + counter.getCount());


        counter = new Counter(3, 10);
        System.out.println("Expected Count: 3 -----> Actual Count: " + counter.getCount());

        counter.increase();
        System.out.println("Expected Count: 13 ----> Actual Count: " + counter.getCount());

        counter.decrease();
        System.out.println("Expected Count: 3 -----> Actual Count: " + counter.getCount());

        counter.decrease();
        System.out.println("Expected Count: -7 ----> Actual Count: " + counter.getCount());
    }

}

Answer 1

第一次实例化 Counter 类时，您的 Counter 类中没有无参数构造函数，因此也应该这样做

Counter counter = new Counter(0,1);

这应该设置初始值和步长值。

或者您可以提供一个无参数构造函数:

public class Counter
{
  private int count;
  private int stepValue;

  public Counter () { //no argument constructor - must be explictly made now
    count=0;
    stepValue = 1;
  }

  public Counter (int initCount, int value)
  {       
    count=initCount;
    stepValue=value;
  }  

  //rest of code
}