每当我的程序到达此for循环并尝试运行它时,我都会报错
for (int m = 0; m < students; m++){
allScores = allScores + scores[m];
学生被宣布为int
allScores与scores []数组一样声明为double。
这是错误消息:
线程“主”中的异常java.lang.ArrayIndexOutOfBoundsException:2
在Lab4.main(Lab4.java:51)
第51行是for(int m = 0; m
编辑:
这是我的整个代码,我可能未正确完成scores []数组:
import java.util.*;
import java.text.*;
public class Lab4 {
public static void main(String[] args){
Scanner s= new Scanner(System.in);
String input;
int students;
int d=1;
double allScores = 0;
char [] answerKey= { 'B' , 'D' , 'A' , 'A' , 'C' , 'A' , 'B' , 'A' , 'C' , 'D' , 'B' , 'A' };
char [] userAnswers = new char[answerKey.length];
DecimalFormat df = new DecimalFormat("#0.0");
System.out.print("how many students are in the class? ");
input = s.nextLine();
students=Integer.parseInt(input);
String [] name = new String[students];
double [] scores = new double[students];
for (int j = 0; j < students; ++j)
{
int correctAnswers=0;
System.out.print("Enter name of student " + (j + 1) + ": ");
name[j] = s.nextLine();
System.out.print("Enter quiz score answers :");
String line = s.nextLine().toUpperCase();
for (int k = 0; k < answerKey.length; k++) {
userAnswers[k] = line.charAt(k);
}
for (int i = 0; i < userAnswers.length; i++)
{
if(userAnswers[i] == answerKey[i])
{
correctAnswers++;
}
}
System.out.println(name[j]);
System.out.println((df.format((((float)(correctAnswers) / answerKey.length)) * 100)) + "%");
scores [d] = ((float)((correctAnswers) / answerKey.length) * 100);
d++;
}
System.out.println("the high score is " + "and the low score is " );
for (int m = 0; m < scores.length; m++){
allScores = allScores + scores[m];
}
System.out.println("Average is:" + ((allScores/students)));
}
}
编辑:
对不起,我读错了51行
scores [d] = ((float)((correctAnswers) / answerKey.length) * 100);
编辑:
新代码不再给我错误消息,但是我似乎无法获得平均分数。
import java.util.*;
import java.text.*;
public class Lab4 {
public static void main(String[] args){
Scanner s= new Scanner(System.in);
String input;
int students;
int d=1;
double allScores = 0;
char [] answerKey= { 'B' , 'D' , 'A' , 'A' , 'C' , 'A' , 'B' , 'A' , 'C' , 'D' , 'B' , 'A' };
char [] userAnswers = new char[answerKey.length];
DecimalFormat df = new DecimalFormat("#0.0");
System.out.print("how many students are in the class? ");
input = s.nextLine();
students=Integer.parseInt(input);
String [] name = new String[students];
double [] scores = new double[students + 1];
for (int j = 0; j < students; ++j)
{
int correctAnswers=0;
System.out.print("Enter name of student " + (j + 1) + ": ");
name[j] = s.nextLine();
System.out.print("Enter quiz score answers :");
String line = s.nextLine().toUpperCase();
for (int k = 0; k < answerKey.length; k++) {
userAnswers[k] = line.charAt(k);
}
for (int i = 0; i < userAnswers.length; i++)
{
if(userAnswers[i] == answerKey[i])
{
correctAnswers++;
}
}
System.out.println(name[j]);
System.out.println((df.format((((float)(correctAnswers) / answerKey.length)) * 100)) + "%");
scores [d] = ((float)((correctAnswers) / answerKey.length) * 100);
d++;
}
System.out.println("the high score is " + "and the low score is " );
for (int m = 0; m < scores.length; m++){
allScores = allScores + scores[m];
}
System.out.println("Average is:" + ((allScores/students)));
}
}
最佳答案
在数组中使用length属性进行迭代。
for (int m = 0; m < scores.length; m++){
allScores = allScores + scores[m];
但是,您提到错误发生在第51行,但第51行是:
scores [d] = ((float)((correctAnswers) / answerKey.length) * 100);
因此,您的d等于或大于scores.length。
我很好奇您为什么将d设为1?
将其更改为0可能会解决问题。
int d=0;
您的代码中的另一个问题是:
((float)((correctAnswers) / answerKey.length) * 100);
更改为
(((float)correctAnswers / answerKey.length) * 100);
否则,您将更改结果,该结果已经是要浮点数的int。那会影响结果。
关于java - 混淆for循环,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/15104116/