在这种情况下，如何让此 java 错误窗口打印出来

Question

我正在编写一个程序，向用户返回 3 个字母字符串的所有可能组合的列表，以便在弹出窗口中输入 3 位电话号码。算法代码是完美的，我不需要帮助。唯一的问题是向用户返回错误消息。为空白输入返回错误消息的代码很好。当用户输入无效字符（不是 2、3、4、5、6、7、8 或 9）时，除非他们的整个输入都是无效字符，否则它不会返回错误消息。例如，如果我输入 123，当字符串中的唯一字符"1"无效时，错误窗口不会弹出。但是，如果我输入"111"（所有字符都无效），则会显示错误消息。如果用户在并非所有字符都无效的情况下输入了无效字符，我想返回错误窗口。示例：输入 123，应给用户一个错误窗口。

import javafx.application.Application;
import javafx.geometry.Pos;
import javafx.geometry.HPos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.scene.text.*;
import javafx.scene.control.Alert; 
import javafx.scene.control.Alert.AlertType; 
public class Runner extends Application 
{
  private TextField input = new TextField();
  private Button outputButton = new Button("Get all possible mnemonics"); 
  @Override
  public void start(Stage primaryStage) 
  {
    GridPane gridPane = new GridPane();
    gridPane.setHgap(5); 
    gridPane.setVgap(5); 
    Text sceneMenu = new Text("Phone digits:n" + "----------n" + "0: No lettersn" + "1: No lettersn" +
                 "2: ABCn" + "3: DEFn" + "4: GHIn" + "5: JKLn" + "6: MNOn" + "7: PQRSn" +
                 "8: TUVn" + "9: WXYZn"); 
    sceneMenu.setFont(Font.font("Arial", FontWeight.BOLD, 16)); 
    gridPane.add(sceneMenu, 5, 0, 1, 10);                     
    gridPane.add(new Label("Enter your three digit phone number:"), 0, 0); 
    gridPane.add(input, 1, 0);
    gridPane.add(outputButton, 1, 7);

    gridPane.setAlignment(Pos.CENTER); 
    input.setAlignment(Pos.BOTTOM_RIGHT);  Textbox.
    GridPane.setHalignment(outputButton, HPos.RIGHT); 


    outputButton.setOnAction(e -> {

    String theInput = input.getText();

      if (theInput.isEmpty())
      {
         Alert error1 = new Alert(AlertType.ERROR);
         error1.setTitle("Blank input");
         error1.setHeaderText("BLANK INPUT!");
         error1.setContentText("Please enter a three digit number.");
         error1.showAndWait();
      }
      else
      {
         String [] matches = new String[]{"2", "3", "4", "5", "6", "7", "8", "9"};
         for (String s : matches)
         {
            if (theInput.contains(s)== false)
            {
               Alert error2 = new Alert(AlertType.ERROR);
               error2.setTitle("Invalid digit");
               error2.setHeaderText("INVALID DIGIT!");
               error2.setContentText("Please enter three digits ranging from 2 through 9");
               error2.showAndWait();
               break;
            }
            else
            {
               calculateMnemonics();
               break;
            }

         }         
       }
   });

    Scene scene = new Scene(gridPane, 700, 600);
    primaryStage.setTitle("Customer order");
    primaryStage.setScene(scene); 
    primaryStage.show(); 
  }
  private void calculateMnemonics() 
  {
    String theInput = input.getText();

    Calculator calc = new Calculator(theInput);
    Alert outputWindow = new Alert(AlertType.INFORMATION);
    outputWindow.setTitle("Mnemonic list");
    outputWindow.setHeaderText("Your mnemonic list for your numbers");
    outputWindow.setContentText(calc.printMnemonics());
    outputWindow.showAndWait();
  }

  public static void main(String[]args) 
  {
    launch(args);
  }
}
import java.util.List;
import java.util.LinkedList;
import java.util.Arrays;
public class Calculator 
{
   private String inputtedNumbers;

   public Calculator() 
   {
      this("");
   }

   public Calculator(String inputtedNumbers)
   {
      this.inputtedNumbers = inputtedNumbers; 
   }
   public String getInputtedNumbers()
   {
      return inputtedNumbers;
   }
   public void setInputtedNumbers(String inputtedNumbers)
   {
      this.inputtedNumbers = inputtedNumbers;
   }
    public List<String> listMnemonics(String digits) 
    {
        String[] letters = {"ABC", "DEF", "GHI", "JKL", "MNO", "PQRS", "TUV", "WXYZ"};
        List<String> rec = new LinkedList<>();
        StringBuilder string = new StringBuilder();
        listMnemonics(digits, 0, letters, string, rec);
        return rec;
    }
    private void listMnemonics(String digits, int number, String[] letters, StringBuilder string, List<String> rec) 
{
        if (digits.length() == number) 
        {
            rec.add(string.toString());
            return;
        }
        String letter = letters[digits.charAt(number) - '2'];
        for (int i = 0; i < letter.length(); i++)
        {
            string.append(letter.charAt(i));
            listMnemonics(digits, number + 1, letters, string, rec);
            string.deleteCharAt(string.length() - 1);
        }

    }

    public String printMnemonics()
    {
          Calculator o = new Calculator();
          List<String> list1 = o.listMnemonics(inputtedNumbers);
          String [] stringArray = list1.toArray(new String[0]);
          return Arrays.toString(stringArray);      
    }
}

Answer 1

以下应该可以解决问题

if (!theInput.matches("[2-9]+"))
{
    Alert error2 = new Alert(AlertType.ERROR);
    error2.setTitle("Invalid digit");
    error2.setHeaderText("INVALID DIGIT!");
    error2.setContentText("Please enter three digits ranging from 2 through 9");
    error2.showAndWait();
}
else
{
    calculateMnemonics();
}

此解决方案使用正则表达式（简称正则表达式）。它测试提供的String是否与2中的任何字符匹配 - 9一次或多次（这就是+正在做的事情）

这甚至会检查输入是否为空，所以如果你愿意，你可以放弃单独的空性检查。如果您不希望它检查空性，则可以使用 !theInput.matches("[2-9]*") 作为检查前一部分是否存在零次或多次的*。