Java 为什么我的if语句不起作用？

我试着检查一个加油泵是否可以免费使用&充满了汽油，然后我试着让这个泵成为排队的汽车使用的泵

Thread carThreads[]=new Thread[TOTAL_CARS];
  try {
    Pump pump1 = new Pump();
    pump1.setName("pump1");
    pump1.setFuelAmount(2000);
    pump1.setState(0);

    Pump pump2 = new Pump();
    pump2.setName("pump2");
    pump2.setFuelAmount(2500);
    pump2.setState(0);

    Pump chosenPump = new Pump();

    if( pump1.getState()==0 && pump1.getFuelAmount()<0 ){
      chosenPump = pump1;
      System.out.println("Pump1 is free and has a fuel amount of: " 
       + (pump1.getFuelAmount()) );
    }

    else if ( pump2.getState()==0 && pump2.getFuelAmount()<0 ){
      chosenPump = pump2;
      System.out.println("Pump2 is free and has a fuel amount of: " 
       + (pump2.getFuelAmount()) );
    }
    //else{
    //  System.out.println("Must wait for the tanker. It should be here soon");
    //}

    Random r = new Random();

    Car car;

    for(int i = 0; i<TOTAL_CARS; i++){
      car = new Car(i, chosenPump);
      System.out.println("car" + car.getID() + " was created");

      (carThreads[i] = new Thread(car)).start();
      Thread.currentThread().sleep(r.nextInt(10000));

      line.enqueue(car);

      chosenPump.usePump( (Car)line.getfirst(), chosenPump, line );

      System.out.println("this is the new line size for gas: " + line.size());
    }//end for
  }//end try
  catch (Exception e){
  }
}//end of main

也许你想要

if(pump1.getState() == 0 && pump1.getFuelAmount() > 0) {

而不是

if(pump1.getState() == 0 && pump1.getFuelAmount() < 0) {

您混淆了>和您正在检查pump1.getFuelAmount0和pump2.getFuelAmount>0

更改pump1.getFuelAmount 0 与pump2相同，重写if语句，如下所示：

if(pump1.getState() == 0 && pump1.getFuelAmount() > 0) {
    chosenPump = pump1;
    System.out.println("Pump1 is free and has a fuel amount of: " 
        + (pump1.getFuelAmount()));
} else if(pump2.getState() == 0 && pump2.getFuelAmount() > 0) {
    chosenPump = pump2;
    System.out.println("Pump2 is free and has a fuel amount of: " 
        + (pump2.getFuelAmount()));
}

您可能还希望在末尾添加一个catch all-other，以便在两个泵都不可用或都没有燃油的情况下进行处理。

几点注释：

首先，泵1和泵2。泵阵列不会减少代码量吗？您可以使用回路检查所有泵的任何情况

---

在你的if声明中：理论上，你不能有一个负的燃料量，所以你要做的就是看看你是否有超过0的燃料量。若你们的燃油量小于0，你们无论如何都不能提供更多的燃油，所以不管它低于0多远，若这个语句不起作用，那个么它就不重要了？有什么错误吗？我们需要更多的细节。为什么要发布你自己的答案，有人已经发布了？