java我的代码正在跳转。。练习穿线

Question

我的问题是，我的代码跳过了自身，停在这里的循环：

   while (!engineOn) {
        System.out.println("Push on. ");
        engStatus = input.nextLine();
        if (engStatus.equals("on")) {
            engineOn = true;
            System.out.println("Starting Engine ");
            rpm = idleRpm;
            System.out.println("RPM: " + rpm + "\nGear: " + gear);
        } else {
            engineOn = false;
            System.out.println("Engine off ");
        }
    }

在InputThread类中

输出到这里：

Output:
MultiThreaded Practice - RPM Shifter 
line 26
Push on. 
on
Starting Engine 
RPM: 800
Gear: 1

终止

忽略代码中我尚未解决的其他问题

我甚至尝试过将线程设置为不同的优先级。还是不走运。我以前也遇到过这个问题，但我从未试图找出原因，只是继续前进。现在对我来说重要的是知道为什么会发生这种情况

这是我的密码。。我到处寻找答案，大多数人认为我的代码可能是错的。但既然这只是一种练习。。这占用了我太多的空闲时间。我试着练习线程和使用我学到的一些随机花絮

我对编码还是新手，更不用说java了

任何提示都会有帮助

package Engine;

import java.util.Scanner;

import Engine.Engine.Gear;
import Engine.Engine.InputThread;
import Engine.Engine.RpmCycle;

public class App extends Thread {

public static void main(String[] args) {
    Scanner input = new Scanner(System.in);
    System.out.println("MultiThreaded Practice - RPM Shifter ");

    // System.out.println("Type start to run program. ");
    // String run = input.nextLine();

    // Call threads.. Wait on input for thread kill or gear switch
    RpmCycle rpm = new RpmCycle();
    Gear gear = new Gear();
    InputThread control = new InputThread();
    Thread.currentThread().setPriority(2);

    control.setPriority(8); 
    gear.setPriority(8);
    rpm.setPriority(8);

    control.start();

    System.out.println("line 26");

    while (Engine.engineOn == true) {

        rpm.start();
        gear.start();
        control.start();

    }

    if(Engine.engineOn==false && Engine.getRpm() != 0){
    System.out.println("You lost: Engine Blown ");
    }
}
}

package Engine;

import java.util.Scanner;

public class Engine {
private static int rpm = 0, idleRpm = 800, rpmLimit = 8000, gear = 1, 
maxGear = 6, waitTime = 100;
public static boolean engineOn = false, asked = false;
public static long startTime = System.currentTimeMillis();
public static String shift = "";

public static int getRpm() {
    return rpm;
}

static Scanner input = new Scanner(System.in);

public static class Gear extends Thread {
    @Override
    public void run() {
        while (shift == "" && asked != true) {
            System.out.println("Shift? ");
            if(shift.equals("1")){
                gear++;
                System.out.println(gear);
            }
            shift="";
        }

        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            System.out.println(e);
        }

    }
}

public static class RpmCycle extends Thread {
    @Override
    public void run() {
        if (rpm <= rpmLimit) {
            System.out.println("RPM: " + rpm + "\nGear: " + gear);
            rpm += 500;
        } else {
            System.out.println("Engine Blown ");
            engineOn = false;
        }

        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            System.out.println(e);

        }

    }
}

public static class InputThread extends Thread {
    @Override
    public void run() {
        @SuppressWarnings("resource")
        Scanner input = new Scanner(System.in);
        String engStatus = null;

        while (!engineOn) {
            System.out.println("Push on. ");
            engStatus = input.nextLine();
            if (engStatus.equals("on")) {
                engineOn = true;
                System.out.println("Starting Engine ");
                rpm = idleRpm;
                System.out.println("RPM: " + rpm + "\nGear: " + gear);
            } else {
                engineOn = false;
                System.out.println("Engine off ");
            }
        }

        try {
            Thread.sleep(100);
        } catch (InterruptedException e) {
            System.out.println(e + ": line 70 in input thread");
        }
    }
}
}