我的代码的问题是，有时它会读取并比较字符串而没有任何问题，但是在比较其他字符串时，它还会引发错误。我认为我的比较功能无法达到标准，我需要在哪里有效设置代码以使我的比较功能有效地工作？
有人可以建议我一些吗？到目前为止，我已经尝试使用bufferedReader比较两个文件。我的代码在某种程度上可以正常工作，但同时遇到错误
“线程“主”中的异常” java.lang.StringIndexOutOfBoundsException：“
我有几张照片直观地描述了我的问题。我认为我的 findtarget 函数不够准确，这就是为什么它会不断抛出这些异常的原因
ERROR：单击此处查看图像。
NO-ERROR：单击此处查看图像。
这是我的两个文件，分别包含肯定和否定关键字。
NEGITIVE：文件扩展名为negi.txt
POSITIVE：文件扩展名为posi.txt
这是用于比较字符串的findtarget函数。
public static int findTarget(String target, String source)
{
int target_len = target.length();
int source_len = source.length();
int add = 0;
// this function check the character whether it is present.
for (int i = 0; i < source_len; ++i) // i is a varialbe used to count upto source_len.
{
int j = 0; // take another variable to count loops
//int[] k = new int[100];
while (add == 0)
{
if (j >= target_len) // count upto target length
{
break;
}
else if (target.charAt(j) != source.charAt(i + j))
{
break;
}
else
{
++j;
if (j == target_len)
{
add++; // this will return 1: true
}
}
}
}
return add;
//System.out.println(""+add);
}
这是我的完整代码，以防万一您想运行它们。
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.*;
import java.io.FileWriter;
public class test {
public static int findTarget(String target, String source)
{
int target_len = target.length();
int source_len = source.length();
int add = 0;
// this function check the character whether it is present.
for (int i = 0; i < source_len; ++i) // i is a varialbe used to count upto source_len.
{
int j = 0; // take another variable to count loops
//int[] k = new int[100];
while (add == 0)
{
if (j >= target_len) // count upto target length
{
break;
}
else if (target.charAt(j) != source.charAt(i + j))
{
break;
}
else
{
++j;
if (j == target_len)
{
add++; // this will return 1: true
}
}
}
}
return add;
//System.out.println(""+add);
}
public static void main(String... args)
{
// function 1
//this variable can be called from any place inside this main function.
int testing1 = 0;
int testing2 = 0;
try {
//reads user review and store them inside source1
Scanner sc = new Scanner(System.in);
System.out.println("Enter your review: ");
String source1 = sc.nextLine();
//establising a file object
File file = new File("posi.txt");
BufferedReader br1 = new BufferedReader(new FileReader(file));
//establising a file object
File file2 = new File("negi.txt");
BufferedReader br2 = new BufferedReader(new FileReader(file2));
String target1; // using a string variable to read the content of the file posi.txt
while ((target1 = br1.readLine()) != null) //as long the condition is not null it will keep printing.
{
testing1 += test.findTarget(target1, source1); // supplying two arguments to findtarget function.
}
String target2; // using a string variable to read the content of the file negi.txt
while ((target2 = br2.readLine()) != null) //as long the condition is not null it will keep printing.
{
testing2 += test.findTarget(target2, source1); // supplying two arguments to findtarget function.
}
br1.close(); br2.close();
System.out.println("positive is:"+testing1 +"\nnegative is :"+testing2); //-not going to print now! :D-
System.out.println("\nthank you for your feedback! :)");
}
catch (IOException e)
{
System.out.println("file error!");
}
// this function is an area where it stores the return value inside a file called pos.txt
try
{
FileWriter myWriter = new FileWriter("pos.txt",true);
// using the true condition makes the line move to the next line.
myWriter.write(" "+testing1);
myWriter.close();
}
catch (IOException e)
{
System.out.println("An error occurred.");
}
// writing neg inside a file called neg.txt
try
{
FileWriter myWriter = new FileWriter("neg.txt",true);
// using the true condition makes the line move to the next line.
myWriter.write(" "+testing2);
myWriter.close();
}
catch (IOException e)
{
System.out.println("An error occurred.");
}
// to evaluate an output based on highest count.
if(testing1 > testing2)
System.out.println("it is positive");
else if (testing1 == testing2)
System.out.println("it is neutral");
else
System.out.println("it is negative");
}
}
答案 0 :(得分：1)
最后，我能够使用称为“ regionmatches” 的 string方法之一来解决此问题。注意：请确保您的肯定文件和否定文件按字母顺序排列。这将为您提供准确的增量。
Github：使用我的链接下载肯定和否定关键字。
public static int findTarget(String target, String source) //method/function
{
String sourcee = source;
String targett = target;
int source_len = sourcee.length();
int target_len = targett.length();
/*
**this function check the character whether it is present using one of string methond called "regionmatch"
**regionMatches(int toffset, String other, int ooffset,int len)
*/
int add = 0;
boolean foundIt = false;
for (int i = 0;i <= source_len - 1;i++)
{
if (sourcee.regionMatches(i, targett, 0, target_len))
{
foundIt = true;
break;
}
}
//checking
if(!foundIt)
{
// do nothing.
}
else
{
add++;
}
return add; //returns incrementation
}
答案 1 :(得分：0)
您将i增加到source的长度，但是您致电
.
.
.
else if (target.charAt(j) != source.charAt(i + j))
.
.
.
在某些时候超过了源代码的长度。
让我们说i == source.length，然后source.charAt(i + j)会在j > 0时引发异常。