java通过读取文件。下一行
当我运行我的程序时,我得到了以下错误。它运行在文件的第一行,但当它返回到main方法中的循环来处理第二行时,我得到的就是这个
java.lang.ArrayIndexOutOfBoundsException: 1
at Popcorn.barGraphByLine(Popcorn.java:94)
at Popcorn.main(Popcorn.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at edu.rice.cs.drjava.model.compiler.JavacCompiler.runCommand(JavacCompiler.java:272)
我的代码:
import java.io.*;
import java.util.*;
public class Popcorn
{
public static void main(String args[])throws IOException
{
printHeading(4, "Popcorn");
//This will call a method to validate a user input as a file name, then
//create a Scanner object to read from the FileReader object
String fileName = validatedFileName();
Scanner inFromFile = new Scanner(new FileReader("Test.txt"));
printBarGraphHeader();
while(inFromFile.hasNextLine())
{
String thisLine = inFromFile.nextLine();
barGraphByLine(thisLine);
}
inFromFile.close();
}
private static String validatedFileName()
{
Scanner keyboardIn = new Scanner(System.in);
System.out.print("Please enter a file name.");
String tryName = keyboardIn.next();
File createFile = new File(tryName);
while(!createFile.exists())
{
System.out.print("The file name you entered is invalid, Please enter a
vaild file name.");
tryName = keyboardIn.next();
createFile = new File(tryName);
}
keyboardIn.close();
return tryName;
}
public static void printBarGraphHeader()
{
System.out.println(" Popcorn Co-Op ");
System.out.println();
System.out.println(" Production in Hundreds ");
System.out.println(" of Pint Jars per Acre ");
System.out.println("Farm Name 1 2 3 4 5 6");
System.out.println(" ---|---|---|---|---|---|");
}
public static void barGraphByLine(String str)
{
String acresString = "";
String jarsString = "";
//This takes any spaces of one or more grouped together and replaces it
//with a single space.
str = str.replaceAll("\\s+" , " ");
//This takes the String str that is composed of the entire line from the file and splits it into two strings at the
//comma, since every name has a comma after it.
String[] splitStr = str.split(", ", 2);
String str1 = splitStr[0];
String str2 = splitStr[1];
String farmName = str1;
Scanner readStr2 = new Scanner(str2);
while(readStr2.hasNext())
{
acresString = readStr2.next();
jarsString = readStr2.next();
}
double acres = Double.parseDouble(acresString);
double jars = Double.parseDouble(jarsString);
double jarsPerAcre = jars/acres;
String graphStars = "";
if(jarsPerAcre < 400)
{
for(int count = 25; count < jarsPerAcre; count += 25)
{
graphStars += "*";
}
for(int count = 375; count >jarsPerAcre;count -= 25)
{
graphStars = graphStars + " ";
}
graphStars = graphStars + "|";
}
else
{
for(int count = 25; count < 400; count += 25)
{
graphStars += "*";
}
graphStars += "#";
for(int count = 400; count < jarsPerAcre; count += 25)
{
graphStars += "*";
}
}
int afterNameSpaceCount = 29 - farmName.length();
for(int count = 0; count < afterNameSpaceCount; count++)
{
farmName = farmName + " ";
}
System.out.println(farmName + graphStars);
readStr2.close();
}
}
# 1 楼答案
请看以下几行:
在这里,您两次调用了
next()
方法,第二次调用没有使用hasNext()
进行显式检查。你有NoSuchElementException
的风险。这与你的问题没有直接关系,但你会发现下一个问题如果你想读两个字符串,你必须每次调用
hasNext()
。但是,请注意:对于您的代码,如果while语句循环超过2次,您将丢失从readStr2
读取的一些值