Question

为什么我的最后两个if语句有非法的表达式开始，否则没有错误？我也不能在这里发布我的代码，因为它想要格式化，我不知道如何正确地做到这一点。如何发布实际的代码视图？

我已更改它，这是已编辑的代码。谢谢你的帮助。

   //Import Java scanner
import java.util.Scanner;

//This class ask a user for their item count and informs the user of the best packing method.
public class PackingOrganizer{
 public static void main(String[] args){
//declare constants and variables
int CARTONS = 4, BOXES = 5;
double containerAmount;
double containerAmount2;
//Get users item count
Scanner input = new Scanner(System.in);
System.out.print("Enter number of items : (All partial items are to be rounded up. ex. 6.5 items is rounded to 7 items)");
double itemCount = input.nextDouble();

//Check to see if input is an integer value
if (itemCount != (int) itemCount)
 System.out.println("Invalid input round all partial numbers up");
//processing phase
  else if (itemCount % CARTONS == 0){
      containerAmount =( itemCount /CARTONS );
      System.out.println("Cartons can be used. The " + itemCount + " items will require " + containerAmount + " cartons ");}
  else if (itemCount % BOXES ==0){
      containerAmount = (itemCount / BOXES);
      System.out.println("Boxes can be used. The " + itemCount + " items will require " + containerAmount + " Boxes ");}
  else if ((itemCount % BOXES != 0) && (itemCount % CARTONS != 0))
      System.out.println("Neither boxes nor cartons can be used for your: " + itemCount + " items.");
  else if ((itemCount % BOXES == 0) && (itemCount % CARTONS == 0 ));{
      containerAmount = (itemCount/BOXES);
      containerAmount2 = (itemCount/CARTONS);
      System.out.println("Cartons can be used. The " + itemCount + " items will require " + containerAmount2 +"." + " Boxes can be used. The " + itemCount + " items will require" + containerAmount +" boxes ");}
 }
}

Answer 1

在第三个其他声明中，您缺少一些括号。整个布尔条件必须括在括号中。此外，您应该使用==而不是=，因为==检查相等性，=是赋值运算符。此外，第三个else if语句在其末尾有一个分号而不是一个左大括号，而紧跟它的语句需要在末尾添加引号，括号和分号。

Answer 2

您在上一个==而非else if

中需要=

=是赋值运算符，而==检查相等（使用原语）。

Answer 3

  else if (itemCount % BOXES != 0) && (itemCount % CARTONS != 0);
      System.out.println("Neither boxes nor cartons can be used for your: " + itemCount + " items. 
  else if (itemCount % BOXES = 0) && (itemCount % CARTONS = 0 );{

应该这样，在else之后没有分号if if statments。你说当你把它们放在那里时你的语句就完成了，编译器会被下面的其他语句弄糊涂。

编辑：也正如其他答案所述，将你的ifs包装在一起，你应该在进行比较时使用==。

  else if ((itemCount % BOXES != 0) && (itemCount % CARTONS != 0))
      System.out.println("Neither boxes nor cartons can be used for your: " + itemCount + " items. 
  else if ((itemCount % BOXES == 0) && (itemCount % CARTONS = 0 )){

Answer 4

也可能包围错误以跟踪所有错误。您需要将=修改为==，如我所提到的另一个问题。这是重构器。您可以将其与当前代码进行比较。

import java.util.Scanner;

//This class ask a user for their item count and informs the user of the best packing method.
public class PackingOrganizer {

    public static void main(String[] args) {
//declare constants and variables
        int CARTONS = 4, BOXES = 5;
        double containerAmount;
        double containerAmount2;
//Get users item count
        Scanner input = new Scanner(System.in);
        System.out.print("Enter number of items : (All partial items are to be rounded up. ex. 6.5 items is rounded to 7 items)");
        double itemCount = input.nextDouble();

//Check to see if input is an integer value
        if (itemCount != (int) itemCount) {
            System.out.println("Invalid input round all partial numbers up");
        } //processing phase
        else if (itemCount % CARTONS == 0) {
            containerAmount = (itemCount / CARTONS);
            System.out.println("Cartons can be used. The " + itemCount + " items will require " + containerAmount + " cartons ");
        } else if (itemCount % BOXES == 0) {
            containerAmount = (itemCount / BOXES);
            System.out.println("Boxes can be used. The " + itemCount + " items will require " + containerAmount + " Boxes ");
        } else if ((itemCount % BOXES != 0)
                && (itemCount % CARTONS != 0)) {
            System.out.println("Neither boxes nor cartons can be used for your: " + itemCount + " items");
        } else if ((itemCount % BOXES == 0)
                && (itemCount % CARTONS == 0)) {

            containerAmount = (itemCount / BOXES);
            containerAmount2 = (itemCount / CARTONS);
            System.out.println("Cartons can be used. The " + itemCount + " items will require " + containerAmount2 + "." + " Boxes can be used. The " + itemCount + " items will require" + containerAmount + " boxes ");
        }
    }
}

为什么我在if语句中得到错误

4 个答案: