创建一个 getCounter() 方法以在调用该方法时进行计数

Question

我正在尝试创建一个 getCounter() 方法，每次调用 getCounter() 方法时都会向上计数。例如，如果该方法被调用 10 次，则输出应为：1,2,3...10。

这是我拥有的当前代码： 主类：

public class JavaLab5 {
    public static final int DEBUG = 0;

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        Student s[] = new Student[10];


        s[0] = new MathStudent("Smith");
        s[1] = new MathStudent("Jack");
        s[2] = new MathStudent("Victor");
        s[3] = new MathStudent("Mike");
        s[4] = new ScienceStudent("Dave");
        s[5] = new ScienceStudent("Oscar");
        s[6] = new ScienceStudent("Peter");
        s[7] = new ComputerStudent("Philip");
        s[8] = new ComputerStudent("Shaun");
        s[9] = new ComputerStudent("Scott");

        for (int loop = 0; loop < 10; loop++) {
            System.out.print(loop);
            System.out.println(s[loop].getSubjects());
        }

    }

}

学生班：

public class Student {
    String name;
    int count 
    public static int instances = 0;

    //Getters
    public  String getName() {
        return this.name;
    }

    // Setters
    public void setName(String name) {
        if (JavaLab5.DEBUG > 3) System.out.println("In Student.setName. Name = "+ name);
        this.name = name;
    }

    /**
     * Default constructor. Populates name,age and gender 
     * with defaults
     */
    public Student() {
        instances++;
        this.name = "Not Set";
    }

    /** 
     * Constructor with parameters 
     * @param name String with the name
    */
    public Student(String name) {
        this.name = name;
    }

    /**
     * Destructor
     * @throws Throwable 
     */
    protected void finalize() throws Throwable {
        //do finalization here
        instances--;
        super.finalize(); //not necessary if extending Object.
    } 

    public void getCounter() {
        for (int x = 0; x < 10; x++) {
        count++;
        System.out.println(count);
    }
    }
    public String toString () {
        return this.name; 
    }

    public String getSubjects() {
      return this.getSubjects();
    }
}

我的问题是如何实现这样的方法来从我的 Main 类中调用它。

Answer 1

两种可能：

您希望每次调用该函数时都进行计数，并为每个对象创建一个新计数器

   public class Student {
        String name;
        int count =0; // every object of class Student will have its own `count`
        //rest of the declrataions / functions
        public void getCounter() {
            System.out.println(++count);
        }
}

您希望每次调用 getCounter 时都有一个计数器计数，而不管您拥有的类 Student 的对象数量如何

public class Student {
String name;
static int count = 0; //static so that multiple object instances of the class share the same `int count`
//rest of the declrataions / functions
public void getCounter() {
    System.out.println(++count);
}
}

Answer 2

如果你的问题是如何实现这样的方法，试试这个：

private int myCounter = 0;

//Use this line instead if you want a global counter for all Studen-Objects
//private static int myCounter = 0;

public void getCounter() {
  System.out.println(myCounter);
  myCounter++;
}

Answer 3

你声明你想计算一个方法被调用了多少次。此外，您还想打印从1 开始到计数的方法调用次数的所有数字的序列。解决并发问题，我的解决方案是：

public class CountTracker {

    private static final AtomicInteger counter = new AtomicInteger();

    public static int count() {
        return counter.incrementAndGet();
    }

    public static void printCounter() {
        int count = counter.get();
        if (count == 0) return;
        StringBuilder builder = new StringBuilder();
        for (int i = 1; i <= count; i++) builder.append(i).append(",");
        builder.deleteCharAt(builder.length() - 1);
        System.out.println(builder);
    }
}

方法count() 表示您要跟踪的方法。我不知道为什么您的解决方案确实包含 Student 类。

Answer 4

只需删除 getCounter 方法中的 for 循环

改变：

public void getCounter() {
    for (int x = 0; x < 10; x++) {
    count++;
    System.out.println(count);
}
}

到：

public void getCounter() {
    System.out.println(count);
    count++;
}