【发布时间】：2014-08-21 00:45:30
【问题描述】：
我正在尝试在 Java 中读取某个文件每当我从脚本中读取一行代码时，它都会显示：
Welcome to DrJava. Working directory is /Users/anu-lion
> run WebCrawler02
!doctype html><html itemscope="" itemtype="http://schema.org/WebPage" lang="ena
java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
at java.util.ArrayList.rangeCheck(ArrayList.java:635)
at java.util.ArrayList.get(ArrayList.java:411)
at WebCrawler02.main(WebCrawler02.java:147)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)
>
我知道这个错误是编码无法达到特定索引时引起的，但我目前不知道如何解决。
这是我的编码。
import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;
import java.util.ArrayList;
import javax.swing.JOptionPane;
public class WebCrawler02 {
ArrayList<String> pagesVisited;
ArrayList<String> pagesToVisit;
public static URL getStartingURLFromUser() {
// This method gets the URL from user.
// Initializes the URL string.
URL startingURL = null;
// String startingString = "http://www.cs.uwec.edu/~stevende/cs145testpages/default.htm";
String startingString = JOptionPane.showInputDialog(null, "Enter a valid URL:");
startingString.toLowerCase();
// catches errors in URL.
try {
startingURL = new URL(startingString);
} catch (MalformedURLException e) {
System.out.println("Bad URL");
System.exit(0);
}
return startingURL;
}
public static String htmlReader(URL webURL) {
// Initializes the strings.
String htmlContent = null;
// Reading the file.
// This try/catch block reads in a file with a reader and creates a
// continuous string.
try {
URLConnection con = webURL.openConnection();
InputStream is = con.getInputStream();
BufferedReader br = new BufferedReader(new InputStreamReader(is));
String line = br.readLine();
while (line != null) {
htmlContent = htmlContent + line + " ";
line = br.readLine();
}
br.close();
} catch (MalformedURLException e) {
System.out.println("Bad URL");
System.exit(0);
} catch (FileNotFoundException e) {
e.printStackTrace();
System.out.println("File not found.");
} catch (IOException e) {
e.printStackTrace();
System.out.println("after try/catch");
}
return htmlContent;
}
public static ArrayList<String> linkParser(String htmlContents) {
// Initializes the strings, boolean, variables and arraylist.
ArrayList<String> listOfLinks = new ArrayList<String>();
int i = 0;
int k = 0;
boolean search = true;
String URL = "";
// This loop creates an array list of URL's.
while (search == true) {
i = htmlContents.indexOf("HREF=", k) + 6;
k = htmlContents.indexOf("\">", i);
URL = htmlContents.substring(i, k);
listOfLinks.add(URL);
if (i == htmlContents.lastIndexOf("HREF=") + 6) {
search = false;
}
}
return listOfLinks;
// System.out.println(htmlContents);
}
public static boolean isBrokenLink(URL currentURL, String theHREF) {
// Initializes the strings, boolean, variables and arraylist.
Boolean isbroken = false;
try {
URL baseURL = new URL(currentURL, theHREF);
URLConnection con = currentURL.openConnection();
HttpURLConnection httpProtocol = (HttpURLConnection) con;
httpProtocol.getResponseCode();
int httpPro = httpProtocol.getResponseCode();
if (httpPro != 200) {
isbroken = true;
}
} catch (MalformedURLException e) {
isbroken = true;
System.out.println("Bad URL1");
} catch (FileNotFoundException e) {
isbroken = true;
e.printStackTrace();
System.out.println("File not found.");
} catch (IOException e) {
isbroken = true;
e.printStackTrace();
System.out.println("after try/catch");
}
return isbroken;
}
public static void displayBrokenLinkReport(
ArrayList<ArrayList<String>> brokenLinks) {
System.out.println("Broken Link Report: \n");
for (int j = 0; j < brokenLinks.size(); j++) {
for (int i = 0; i < brokenLinks.get(j).size(); i++) {
if (j == 0) {
System.out.println("Page " + brokenLinks.get(j).get(i));
} else {
System.out.println("Broken link "
+ brokenLinks.get(j).get(i));
}
}
}
}
public static void main(String[] args) {
// Initializes the arraylists and the array<arraylist
ArrayList<URL> pagesVisited = new ArrayList<URL>();
ArrayList<URL> pagesToVisit = new ArrayList<URL>();
ArrayList<String> listOfLinks = null;
ArrayList<String> badLinks = null;
ArrayList<ArrayList<String>> brokenLinks = new ArrayList<ArrayList<String>>();
int i = 0;
// calls the getStartingURLFromUser method which returns the string.
pagesToVisit.add(getStartingURLFromUser());
while (!pagesToVisit.isEmpty()) {
URL baseURL = pagesToVisit.get(0);
pagesVisited.add(baseURL);
pagesToVisit.remove(0);
// calls the htmlReader method which returns the string.
String htmlContent = htmlReader(baseURL);
// calls the linkParser method which returns the array list.
listOfLinks = linkParser(htmlContent);
// calls the isBrokenLink method which returns the string.
for (i = 0; i <= (listOfLinks.size()); i++) {
boolean isBL = isBrokenLink(baseURL, listOfLinks.get(i));
System.out.println(listOfLinks.get(i) + "a");
if (isBL) {
System.out.println(listOfLinks.get(i));
badLinks.add(listOfLinks.get(i));
} else {
// catches errors in URL.
URL nextURL = null;
try {
nextURL = new URL(baseURL, listOfLinks.get(i));
if (!pagesVisited.contains(nextURL)) {
pagesToVisit.add(nextURL);
}
} catch (MalformedURLException e) {
e.printStackTrace();
System.out.println("Bad URL2");
}
}
}
brokenLinks.add(badLinks);
}
displayBrokenLinkReport(brokenLinks);
}
}
提前致谢。
【问题讨论】：
-
您的输入是什么导致您出现此错误？
-
问题很明显：您试图从长度为 1 的 ArrayList 中提取索引 1（因此唯一有效的索引是 0）。您需要做更多的工作来显示导致问题的代码区域 - 异常会告诉您，但没有多少人会检查您的所有代码来为您找出问题。
-
错误出现在第 147 行，无论它在哪里。
-
这是一个容易调试的问题。你试过什么？？