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如何修复StringOutOfBoundsException?[重复]

java.util.scanner try-catch char error-handling java

-1

Walker · 技术社区 · 2 年前

我正在为一个学校项目编写代码,而我在第50行中不断得到StringOutOfBoundsException。

这是我的代码:

import java.io.*; 
import java.util.*;

class Main {
  public static void main(String[] args) {
    String end = "e";
    int [][] seat = new int [12][20];
    for (int rows = 0; rows<seat.length;rows++){
        for (int cols = 0; cols<seat[0].length; cols++){
          seat[rows][cols] = 0; 
        }
      }
    while (end!="q"){
      System.out.println();
      System.out.print("\t");
      for (int cols = 0; cols<seat[0].length;cols++){
        System.out.print(cols+1 + "\t");
        }
      System.out.println();
      for (int rows = 0; rows<seat.length;rows++){
        System.out.print(rows+1 + "\t");
        for (int cols = 0; cols<seat[0].length; cols++){
          System.out.print("[" + seat[rows][cols] + "]" + "\t");
        }
        System.out.print( rows+1 );
        System.out.println();
      }
      System.out.println();
      String h = "Cinema Screen";
      System.out.println(String.format("%45s", h));
      
      try{
        System.out.println();
        System.out.print("Which column is your desired seat in? ");
        Scanner reader = new Scanner(System.in);
        int column = reader.nextInt();
        System.out.print("Which row is your desired seat in? ");
        int row = reader.nextInt();
        System.out.println();
        if (seat[row-1][column-1] == 1){
          System.out.print("This seat is already taken. ");
        }
        else if (seat[row-1][column-1] != 1){
          seat[row-1][column-1] = 1;
          System.out.print("\t");
        }
        System.out.println();
        System.out.print("Would you like to continue? ");
        String cont = reader.nextLine();
        char contin = cont.charAt(0);
        if (contin == 'n' || contin == 'N'){
          end = "q";
        }
      } 
      catch (InputMismatchException e){
        System.out.println();
        System.out.print("The input has to be a valid integer.");
      }
      catch (ArrayIndexOutOfBoundsException e){
        System.out.println();
        System.out.print("Please choose an integer representing an existing seat.");
      }
    }
    
    
  }
}

我一直收到的例外是 char contin = cont.charAt(0); ,它一直说索引0超出范围。

我不知道我做错了什么,我不想用try-catch语句来修复它。有人能帮我吗?

2 回复 | 直到 2 年前

Tyler VanHaren 2 年前

当您调用nextInt()时(或任何形式),扫描器标记当前行并返回下一个标记,但被解析为您调用的类型,但它不会刷新整行。如果在包含“4 5”的单行上调用两次nextLine(),它会同时返回这两个值——这里的问题是,当在nextLine()之后调用nextLine()时,实际上是在缓冲区中获得当前行的其余部分(在您的情况下,似乎只是一个行尾字符)。

https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/Scanner.html 对于扫描仪上的完整文档。

tntzx 2 年前

所以基本上问题是当你在输入行号后按enter键时。在该场景中,会跳过nextline()添加读取器。nextLine();之前 String cont=读卡器。nextLine();

 import java.io.*; 
 import java.util.*;

 class Main {
 public static void main(String[] args) {
 String end = "e";
 int [][] seat = new int [12][20];
 for (int rows = 0; rows<seat.length;rows++){
    for (int cols = 0; cols<seat[0].length; cols++){
      seat[rows][cols] = 0; 
    }
  }
 while (end!="q"){
  System.out.println();
  System.out.print("\t");
  for (int cols = 0; cols<seat[0].length;cols++){
    System.out.print(cols+1 + "\t");
    }
  System.out.println();
  for (int rows = 0; rows<seat.length;rows++){
    System.out.print(rows+1 + "\t");
    for (int cols = 0; cols<seat[0].length; cols++){
      System.out.print("[" + seat[rows][cols] + "]" + "\t");
    }
    System.out.print( rows+1 );
    System.out.println();
  }
  System.out.println();
  String h = "Cinema Screen";
  System.out.println(String.format("%45s", h));
  
  try{
    System.out.println();
    System.out.print("Which column is your desired seat in? ");
    Scanner reader = new Scanner(System.in);
    int column = reader.nextInt();
    System.out.print("Which row is your desired seat in? ");
    int row = reader.nextInt();
    System.out.println();
    if (seat[row-1][column-1] == 1){
      System.out.print("This seat is already taken. ");
    }
    else if (seat[row-1][column-1] != 1){
      seat[row-1][column-1] = 1;
      System.out.print("\t");
    }
    
    
    System.out.println();
    System.out.print("Would you like to continue? ");
    reader.nextLine();  // newline 
    String cont = reader.nextLine();
    char contin = cont.charAt(0);
    if (contin == 'n' || contin == 'N'){
      end = "q";
    }
    
    
    
  } 
  catch (InputMismatchException e){
    System.out.println();
    System.out.print("The input has to be a valid integer.");
  }
  catch (ArrayIndexOutOfBoundsException e){
    System.out.println();
    System.out.print("Please choose an integer representing an existing seat.");
  }
}


}
}