java - 必须输入两次才能扫描仪读取

Question

因此，在这段代码中，在“run”方法中的“Run”类下，扫描仪似乎不想从第一次尝试中获取输入，只有在第二行才获取输入。我说第二行是因为我输入输入然后按两次回车键，然后在第三行输入输入，它会读取第二行，在这种情况下什么也没有。

我尝试过 BufferedReader 得到了相同的结果，所以我相信我正在做一些愚蠢的事情并忽略了一些事情。

import java.util.Scanner;
import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;

import java.io.*;

class Global {
    public static int stop = -1;
}

public class DataSort {

    public static void main(String[] args){

        Timer timer = new Timer();
        Direct swit = new Direct();
        Run mprog = new Run();
        Help hlp = new Help();

        String newline = System.getProperty("line.separator");

        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        Scanner console = new Scanner(System.in);

        System.out.println(newline);
        System.out.println("Welcome to Data Sort! This Program is designed to sort information about targets discoverd by UAV and place the data in a table." + newline);
        System.out.print("For help, press any key. To continue, please wait. ");
        timer.schedule(swit, 3000);

        try {
            Global.stop = in.read();
        } 

        catch(IOException e) {
            e.printStackTrace();
        }

        try {
            in.close();
        }

        catch(IOException e) {
            e.printStackTrace();
        }
    }
}

class Direct extends TimerTask {

    public void run() {

        Run mprog = new Run();
        Help hlp = new Help();

        if(Global.stop != -1){
            System.out.println("Help");
            hlp.run();
        }

        if(Global.stop == -1) {
            System.out.println("Main");
            mprog.run();
        }
    }
}


class Help {

    public static void run() {
        String newline = System.getProperty("line.separator");

        System.out.print(newline);
        System.out.println("Entering Help Mode!" + newline);

        System.out.println("Entered Help Class");
        //String help = console.nextLine();
    }
}

class Run {

    public static void run() {

        /*EnterAll eall = new EnterAll();
        EnterCoords ecoords = new EnterCoords();
        EnterRelation erelat = new EnterRelation();
        EnterColor ecolor = new EnterColor();
        EnterShape eshape = new EnterShape();
        Coordinates coords = new Coordinates();
        Relation relat = new Relation();
        Color color = new Color();
        Shape shape = new Shape();
        List list = new List();
        Save save = new Save();
        SaveAs saveas = new SaveAs();*/

        String newline = System.getProperty("line.separator");
        Scanner console = new Scanner(System.in);

        System.out.print(newline);
        System.out.println("Initializing Main Program." + newline);
        System.out.println("************************** MAIN MENU *************************" + newline);
        System.out.println("Enter Coords \t Enter Relat \t Enter Color \t Enter Shape"+newline);
        System.out.println("Coordinates \t Relation \t Color \t \t Shape" + newline);
        System.out.println("Help \t \t List \t \t Save \t \t Save As" + newline);
        System.out.println("**************************************************************" + newline);

        System.out.print("Enter your selection or type All to enter lines consecutively: ");
        String raw = console.nextLine();

        System.out.println(raw);

        String select = errorCheck(raw);

        if (select.equals("All")){
        }

        if (select.equals("Enter Coords")){
        }

        if (select.equals("Enter Relat")){
        }

        if (select.equals("Enter Color")){
        }

        if (select.equals("Enter Shape")){
        }

        if (select.equals("Coordinates")){
        }

        if (select.equals("Relation")){
        }

        if (select.equals("Color")){
        }

        if (select.equals("Shape")){
        }

        if (select.equals("Help")){
        }

        if (select.equals("List")){
        }

        if (select.equals("Save")){
        }

        if (select.equals("Save As")){
        }
    }

    private static String errorCheck(String raw) {

        String select = raw;
        return select;
    }
}

Answer 1

你的问题在于

public class DataSort {...... Global.stop = in.read(); ......} 

因为in.read是读取Integer输入的。它不读取行尾字符。这就是为什么当你输入选择字符串并按回车键后它会变得毫 headless 绪。

问候，拉维