Question

我正在尝试将我的int“n”设置为由用户输入定义。但它永远不会被设定，我不确定是什么问题。我不是很擅长java和这是IS作业。我认为我的问题非常基本，但我被困住了。所以，重申一下我的问题。为什么我不能将我的int设置为用户输入？ “n”问题不是实际的作业，但为了让我的作业正常工作，必须设置“n”。

package printer.java;

import java.util.Queue;
import java.util.LinkedList;
import java.util.Timer;
import java.util.TimerTask;
import java.util.Random;
import java.util.Scanner; 

public class PrinterJava {
// Declaring ints needed
int count = 0;
int jobCount = 0;
int done = 0;
int time = 0;
int jobTimerDelay = 1000;
int jobTimerPeriod = 1000;
int timeTimerDelay = 1000;
int timeTimerPeriod = n * 60 * 1000;

// declaring timers needed
    Timer jobTimerTimer = new Timer();
    Timer timeTimerTimer = new Timer();
// This is a timer that is supposed to create new "pages" every 5 seconds. 
//the pages have to be a random "size between 1 and 5 pages long"

public void jobTimer() {
    jobTimerTimer.scheduleAtFixedRate(new TimerTask() {
        @Override
        public void run() {
            count++;
            Random dom = new Random();
            int p = dom.nextInt(5) + 1;
            if (count % 5 == 0) {
                pages page = new pages();  // Creates a new page every 5 seconds
                page.pages = p;
                jobCount++;
                    jobQueue.offer(page); // pushes the newly created pages into the queue
                    System.out.println("A new Job has been created! Job queue size: " + jobQueue.size());
                    System.out.println("Total Jobs created: " + jobCount);
                } else if (!jobQueue.isEmpty() && count > 2 && count % 2 == 0) {
                    done++;
                    jobQueue.remove();
                    System.out.println("Job printed successfully! total jobs printed: " + done);
                }
            }
        }, jobTimerDelay, jobTimerPeriod);


   }
    // this is the queue that holds the pages
    Queue<Object> jobQueue = new LinkedList<Object>();

    public class pages { // pages

        int pages;
        // constructor

        public pages() {
        }

        public pages(int NumPages) {
            this.pages = NumPages;
        }
    }

    public void timerTwo() {
timeTimerTimer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                PrinterJava runOne = new PrinterJava(); // creats an instance of my page creator
                runOne.jobTimer();
                System.out.println("Please Enter Run time in minutes as an integer: ");
                Scanner scan = new Scanner(System.in); 
                int n = scan.nextInt(); 
            }
        }, timeTimerDelay, timeTimerPeriod);


    }

    public static void main(String[] args) {
        PrinterJava runTwo = new PrinterJava(); // creats an instance of my page creator
        runTwo.timerTwo();
    }
}

Answer 1

当你说int n你宣布一个新变量时，所以在下一行之后你就不再有它了。另外，我没有看到n被声明为实例变量或其他任何地方。

如果您在行int n = scan.nextInt();之后设置断点并查看是否在那里设置了断点（或者您可以使用System.out.println()将其打印出来，该怎么办？

Answer 2

此行不会编译，因为n尚未定义：

int timeTimerPeriod = n * 60 * 1000;

但是，如果它不会按预期工作：

timeTimerTimer.scheduleAtFixedRate(new TimerTask() {...}, timeTimerDelay, timeTimerPeriod);

因为在n方法中定义了TimerTask.run()。要解决这个问题，请考虑进行此更改：

int timeTimerPeriod = 60 * 1000; // instance variable
int n = 0;

...

public void timerTwo() {
    System.out.println("Please Enter Run time in minutes as an integer: ");
    Scanner scan = new Scanner(System.in); 
    n = scan.nextInt(); // <-- read n here for first time

    timeTimerTimer.scheduleAtFixedRate(new TimerTask() {...}, timeTimerDelay, timeTimerPeriod * n);
}

通过扫描仪声明变量？

2 个答案: