错误消息：运算符 <不能应用于 boolean,int

Question

我是编程新手，正在做一些练习。在本练习中，我应该编写一个程序，从程序用户那里读取三个数字。该程序应该找到最小的数字，并打印哪个是最小的数字。 这是我的代码：

import javax.swing.JOptionPane;

public class Smallestnumber
{
  public static void main( String args[] )
    {
    // Defining variables:
    String firstnumberstring;
    String secondnumberstring;
    String thirdnumberstring;
    String result;
    int firstnumber;
    int secondnumber;
    int thirdnumber;

    // Making input frames:
    firstnumberstring = JOptionPane.showInputDialog( "Write first number!" );
    secondnumberstring = JOptionPane.showInputDialog( "Write second number!");
    thirdnumberstring = JOptionPane.showInputDialog( "Write third number!" );

    // Converting stringvalues to int values:
    firstnumber = Integer.parseInt( firstnumberstring );
    secondnumber = Integer.parseInt( secondnumberstring );
    thirdnumber = Integer.parseInt( thirdnumberstring );

    // Initialising printstring to an empty string:
    result = "";

    if ( firstnumber < secondnumber < thirdnumber )
    result = firstnumber + " is the smallest number!";

    if ( firstnumber < thirdnumber < secondnumber )
    result = firstnumber + " is the smallest number!";

    if ( secondnumber < firstnumber < thirdnumber )
    result = secondnumber + " is the smallest number!";

    if ( secondnumber < thirdnumber < firstnumber )
    result = secondnumber + " is the smallest number!";

    if ( thirdnumber < firstnumber < secondnumber )
    result = thirdnumber + " is the smallest number!";

    if ( thirdnumber < secondnumber < firstnumber )
    result = thirdnumber + " is the smallest number!";

    // Making conclusion box:
    JOptionPane.showMessageDialog( null, result, "Conclusion:", JOptionPane.INFORMATION_MESSAGE );

    } // End of main method
} // End of class Smallestnumber

这是错误消息：

Smallestnumber.java:29: operator < cannot be applied to boolean,int
    if ( firstnumber < secondnumber < thirdnumber )
                                    ^
Smallestnumber.java:32: operator < cannot be applied to boolean,int
    if ( firstnumber < thirdnumber < secondnumber )
                                   ^
Smallestnumber.java:35: operator < cannot be applied to boolean,int
    if ( secondnumber < firstnumber < thirdnumber )
                                    ^
Smallestnumber.java:38: operator < cannot be applied to boolean,int
    if ( secondnumber < thirdnumber < firstnumber )
                                    ^
Smallestnumber.java:41: operator < cannot be applied to boolean,int
    if ( thirdnumber < firstnumber < secondnumber )
                                   ^
Smallestnumber.java:44: operator < cannot be applied to boolean,int
    if ( thirdnumber < secondnumber < firstnumber )
                                    ^
6 errors

如何让程序正常工作？

Answer 1

你不能做 thirdnumber <第二个数 < Java 中的firstnumber，将其解释为 (thirdnumber < secondarynumber) (thirdnumber < secondarynumber) firstnumber，将 true 或 false 与数字进行比较。

你想要的是结合这样的两个条件：

if ( firstnumber < secondnumber && secondnumber < thirdnumber )
result = firstnumber + " is the smallest number!";