Total not adding up

问题

I'm working on a classwork in high school comp sci class and i have come across this problem. the total is not adding. can someone tell me why?

import javax.swing.*;

public class TimeSheets {

  public static void main(String[] args) {

    String loc;
    String[] day = new String[7];       
    String time1;
    String time2;
    int location;
    double total = 0;
    int num = 1;
    int x = 0;
    int y = 0;
    double clock1 = 0;
    double clock2 = 0;
    double hour;

    loc = JOptionPane.showInputDialog(null, "Enter your Work Location");
    location = Integer.parseInt(loc);

    while (x < 7 && y < 7) {

      day[x] = JOptionPane.showInputDialog(null, "Enter Day "+num+" 's Starting code");
      day[y] = JOptionPane.showInputDialog(null, "Enter Day "+num+" 's Ending code");
      time1 = day[x];
      time2 = day[y];

      if (time1 == "1") {
        clock1 = 9;
      }
      if (time1 == "2") {
        clock1 = 9.5;
      }
      if (time1 == "3") {
        clock1 = 10;
      }
      if (time1 == "4") {
        clock1 = 10.5;
      }
      if (time1 == "5") {
        clock1 = 11;
      }
      if (time1 == "6") {
        clock1 = 11.5;
      }
      if (time1 == "7") {
        clock1 = 12;
      }
      if (time1 == "8") {
        clock1 = 12.5;
      }
      if (time1 == "9") {
        clock1 = 13;
      }
      if (time1 == "A") {
        clock1 = 13.5;
      }
      if (time1 == "B") {
        clock1 = 14;
      }
      if (time1 == "C") {
        clock1 = 14.5;
      }
      if (time1 == "D") {
        clock1 = 15;
      }
      if (time1 == "E") {
        clock1 = 15.5;
      }
      if (time1 == "F") {
        clock1 = 16;
      }
      if (time1 == "G") {
        clock1 = 16.5;
      }
      if (time1 == "H") {
        clock1 = 17;
      }

      if (time2 == "1") {
        clock2 = 9;
      }
      if (time2 == "2") {
        clock2 = 9.5;
      }
      if (time2 == "3") {
        clock2 = 10;
      }
      if (time2 == "4") {
        clock2 = 10.5;
      }
      if (time2 == "5") {
        clock2 = 11;
      }
      if (time2 == "6") {
        clock2 = 11.5;
      }
      if (time2 == "7") {
        clock2 = 12;
      }
      if (time2 == "8") {
        clock2 = 12.5;
      }
      if (time2 == "9") {
        clock2 = 13;
      }
      if (time2 == "A") {
        clock2 = 13.5;
      }
      if (time2 == "B") {
        clock2 = 14;
      }
      if (time2 == "C") {
        clock2 = 14.5;
      }
      if (time2 == "D") {
        clock2 = 15;
      }
      if (time2 == "E") {
        clock2 = 15.5;
      }
      if (time2 == "F") {
        clock2 = 16;
      }
      if (time2 == "G") {
        clock2 = 16.5;
      }
      if (time2 == "H") {
        clock2 = 17;
      }

      hour = clock2 - clock1;
      total = hour + hour;

      JOptionPane.showMessageDialog(null, "total hour" + total);
      x++;
      y++;
      num++;

    }
  }
}

回答1:

check string equality with equals() method. == operator checks if two reference variables refer to the same string object. equals() method check if two strings are meaningfully equal.

    if (time1 == "1") {

sholud be

    if (time1.equals("1")) {

and also all your other if'statements. I strongly advise you to make use of nested-if else rather than a million if statements.Like:

if (time1.equals("1")) {
        clock1 = 9;
      }
      else if (time1.equals("2")) {
        clock1 = 9.5;
      }
    ..........

回答2:

Use this approach for static map using ENUM

public enum TimeToClock{
    1(9),
    2(9.5);
    //so on

    public final double value;

    private static final Map<Integer,TimeToClock> map;
    public static final TimeToClock[] VALUES = values();
    static {
        map = new HashMap<Integer,TimeToClock>(3);
        for (TimeToClock type : VALUES) {
            map.put(type.value, type);
        }
    }   

    TimeToClock(int value){
        this.value = value;
    }   
    public double getValue(){
        return this.value;
    }

    public static TimeToClock get(int key){
        return map.get(key);
    }
}

Use:

double value = TimeToClock.get(2).getValue();

回答3:

Your total at the end looks like it's worked out incorrectly.

total = hour + hour;

Would it not make more sense to be...

total = total + hour;

So you are incrementing the total rather than just resetting it after each loop iteration?

来源：https://stackoverflow.com/questions/13685434/total-not-adding-up