java中的正则表达式模式/数组问题

Question

我正在为下个月即将到来的考试而学习，并研究一些基本问题。这是一个程序，需要输入几个句子并重新打印包含特定字符串的任何句子，在本例中为“模式”

我的尝试如下所示，它已编译，但我在尝试运行它时收到以下错误：

   Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 10
at Grep.main(Grep.java:18)

import java.util.Scanner;
import java.io.*;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

class Grep {

    public static void main(String[] args) {

        Pattern pattern = Pattern.compile("[Pp]attern");
        String sentences[] = new String[10];
        Scanner scanner = new Scanner(System.in); 

        System.out.println("Please enter some sentences: ");

        for (int i = 0; i <= sentences.length; i++) {
            String s = scanner.next(); 
            sentences[i] = s;
        }

        for (int i = 0; i < sentences.length; i++) { 
            Matcher matcher = pattern.matcher(sentences[i]);
            while (matcher.find()) {
                System.out.println(sentences[i]);
            }
        }
    }
}

Answer 1

试试这个。它起作用了

小贴士: 确保使用nextLine（），以便输入内容能够阅读完整的句子。我将while循环切换为for循环中的if语句。那里不需要两个环路。我还把你的第一个for循环压缩成一行。如果只需要一秒钟，则无需创建字符串变量。只需完全跳过这一步，直奔主题！祝你好运，希望这有帮助

下面是一个反映您的程序，但现在可以运行了

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Grep 
{
    public static void main(String[] args) 
    {
        Pattern pattern = Pattern.compile("[Pp]attern");
        String sentences[] = new String[3];
        Scanner scanner = new Scanner(System.in);

        System.out.println("Please enter some sentences: ");

        for (int i = 0; i < sentences.length; i++) 
            sentences[i] = scanner.nextLine();

        for (int i = 0; i < sentences.length; i++) 
        { 
            Matcher matcher = pattern.matcher(sentences[i]);
            if (matcher.find()) 
                System.out.println(sentences[i]);
        }
    }
} 

下面是我如何编写这个程序的。包括澄清意见

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Grep 
{
    public static void main(String[] args) 
    {
        // Initialize and Declare Variables
        Pattern pattern = Pattern.compile("[Pp]attern");
        String sentences[] = new String[3];
        Scanner scanner = new Scanner(System.in);
        int foundCount = 1;


        // Present A Title For The End User
        System.out.println("This Program Will Catch Sentences With The Term Pattern.\n");


        // Read The Inputs From The Users
        for (int i = 0; i < sentences.length; i++)
        {
            System.out.print("Enter Sentence #" + (i+1) + ":  ");
            sentences[i] = scanner.nextLine();
        }


        // Line Break
        System.out.println();


        // Write Sentences That Include The Term Pattern
        for (int i = 0; i < sentences.length; i++) 
        { 
            Matcher matcher = pattern.matcher(sentences[i]);
            if (matcher.find())
            {
                System.out.println(foundCount + ")  " + sentences[i]);
                foundCount++;
            }
        }
    }
}

Answer 2

for (int i = 0; i <= sentences.length; i++) {

数组中有多少项？最后一个索引是什么？循环使用的最后一个索引是什么？你的循环总共访问多少个句子

Answer 3

试一试

for (int i = 0; i < sentences.length; i++)

你会没事的：）

Answer 4

for (int i = 0; i <= sentences.length; i++) {

<=必须是<，因为从0开始，有10个项目，所以i必须从0到9

Answer 5

问题出在代码的第:18行，它是for (int i = 0; i <= sentences.length; i++)，应该是for (int i = 0; i < sentences.length; i++)

当您在代码中的下一个for循环中使用<而不是<=