java - 将 .txt 导入数组，通过对话框输出

Question

所以我已经在这段代码上工作了一段时间，在添加 JOptionPane 之前我测试了它，有 0 个错误，然后我添加了 JOptionPane 并得到了 27-38 之间的错误。所以我显然在我的 JOptionPane 中做错了什么，但我不确定是什么，我大部分时间只有使用 Scanner 的经验，所以任何帮助将不胜感激。谢谢!

import javax.swing.JOptionPane;
import java.io.*;
import java.util.ArrayList;
import java.util.Scanner;

public class TestScores
{
    public static void main(String args[]) throws IOException {
        String filename = ("scores.txt");
        File file = new File(filename);
        Scanner inputFile = new Scanner(file);

        while (inputFile.hasNextInt()) {
            String line = inputFile.nextLine();
            ArrayList<Integer> scores = new ArrayList<Integer>();
            Scanner scanner = new Scanner(line);
            scanner.useDelimiter(",");

            while(scanner.hasNextInt()) {
                scores.add(scanner.nextInt());
            }

            scanner.close();
        }
    }

    public static int averageScore(int[] numbers) {
        int total = 0;
        for (int i : numbers) {
            total += i;
        }
        return total/(numbers.length);
    }

    public static int modeOfScores(int[] numbers) {
        int modeCount = 0;
        int mode = 0;     
        int currCount = 0;    
        int currElement;

        for (int candidateMode : numbers) {
            currCount = 0;

            for (int element : numbers) {
                if (candidateMode == element) {
                    currCount++;
                }
            }

            if (currCount > modeCount) {
                modeCount = currCount;
                mode = candidateMode;
            }
        }

        return mode;
    }

    public static int lowestScore(int[] numbers) {
        int lowest = numbers[0];

        for(int i = 1; i > numbers.length; i++) {
            if(numbers[i] < lowest) {
                lowest = numbers[i];
            }
        }
        return lowest;
    }

    public static int largestScore(int[] numbers) {  
        int largest = numbers[0];  
        for(int i = 1; i < numbers.length; i++) {  
            if(numbers[i] > largest) {  
                largest = numbers[i];  
            }
        }  
        return largest;
    }
    JOptionPane.showMessageDialog (null, "The Average number is: " + total);
    JOptionPane.showMessageDialog (null, "The Mode number is: " + mode);
    JOptionPane.showMessageDialog (null, "The Lowest number is: " + lowest);
    JOptionPane.showMessageDialog (null, "The Largest number is: " + largest);
}

编辑:这是我得到的所有错误，全部来自 JOptionPane 部分

TestScores.java:86: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                ^
TestScores.java:86: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                 ^
TestScores.java:86: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                       ^
TestScores.java:86: error: ')' expected
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                                                ^
TestScores.java:86: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                                                  ^
TestScores.java:86: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                                                               ^
TestScores.java:86: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                                                                ^
TestScores.java:86: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                                                                 ^
TestScores.java:86: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Average number is: " +(averageScore));
                                                                                  ^
TestScores.java:87: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
              ^
TestScores.java:87: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                 ^
TestScores.java:87: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                       ^
TestScores.java:87: error: ')' expected
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                                             ^
TestScores.java:87: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                                               ^
TestScores.java:87: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                                                            ^
TestScores.java:87: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                                                             ^
TestScores.java:87: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                                                              ^
TestScores.java:87: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Mode number is: " +(modeOfScores));
                                                                               ^
TestScores.java:88: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
              ^
TestScores.java:88: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                 ^
TestScores.java:88: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                       ^
TestScores.java:88: error: ')' expected
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                                               ^
TestScores.java:88: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                                                 ^
TestScores.java:88: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                                                             ^
TestScores.java:88: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                                                              ^
TestScores.java:88: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                                                               ^
TestScores.java:88: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowestScore));
                                                                                ^
TestScores.java:89: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
              ^
TestScores.java:89: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                 ^
TestScores.java:89: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                       ^
TestScores.java:89: error: ')' expected
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                                                ^
TestScores.java:89: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                                                  ^
TestScores.java:89: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                                                               ^
TestScores.java:89: error: illegal start of type
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                                                                ^
TestScores.java:89: error: <identifier> expected
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                                                                 ^
TestScores.java:89: error: ';' expected
   JOptionPane.showMessageDialog(null, "The Largest number is: " +(largestScore));
                                                                                  ^
TestScores.java:90: error: reached end of file while parsing
}

^

Answer 1

首先有两个问题。您的最后 4 个方法调用在类中是松散的。

JOptionPane.showMessageDialog(null, "The Average number is: " +(total));
JOptionPane.showMessageDialog(null, "The Mode number is: " +(mode));
JOptionPane.showMessageDialog(null, "The Lowest number is: " +(lowest));
JOptionPane.showMessageDialog(null, "The Largest number is: " +(largest));

在这种情况下，它们需要位于方法内部。

第二个总数、众数、最低值和最大值仅在各自的方法范围内局部定义。

您需要将它们存储为 TestScores 的成员。

编辑#1

小提示，Java 是用 lowerCamelCase 编写的 http://en.wikipedia.org/wiki/CamelCase

编辑#2

我浏览了整个代码，发现了很多错误。

1. Java 中的数组与ArrayList不同。所以你必须选择一个，在这种情况下，ArrayList 将为您解决问题，如下所示你可以处理得更优雅。
2. ArrayList 没有 array 那样的索引。相反，你必须使用它的方法 get(index)它由 . 运算符访问。
3. 由于这些方法返回 total、mode、lowest 和 largest 的值，为什么不调用它们直接在您的 showMessageDialog() 中？

编辑#3

我现在没有用于测试的scores.txt。这不会产生编译错误。

import javax.swing.JOptionPane;
import java.io.*;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class TestScores
{
    public static void main(String args[]) throws IOException { 
        String filename = ("scores.txt");
        File file = new File(filename);
        Scanner inputFile = new Scanner(file);

        List<Integer> scores = new ArrayList<Integer>();

        while (inputFile.hasNextInt()) {
            String line = inputFile.nextLine();

            Scanner scanner = new Scanner(line);
            scanner.useDelimiter(",");

            while(scanner.hasNextInt()) {
                scores.add(scanner.nextInt());
            }

            scanner.close();
        }

        JOptionPane.showMessageDialog (null, "The Average number is: " + averageScore(scores));
        JOptionPane.showMessageDialog (null, "The Mode number is: " + modeOfScores(scores));
        JOptionPane.showMessageDialog (null, "The Lowest number is: " + lowestScore(scores));
        JOptionPane.showMessageDialog (null, "The Largest number is: " + largestScore(scores));
    }

    public static int averageScore(List<Integer> numbers) {
        int total = 0;
        for (int i : numbers) {
            total += i;
        }
        return total/(numbers.size());
    }

    public static int modeOfScores(List<Integer> numbers) {
        int modeCount = 0;
        int mode = 0;     
        int currCount = 0;    
        int currElement;

        for (int candidateMode : numbers) {
            currCount = 0;

            for (int element : numbers) {
                if (candidateMode == element) {
                    currCount++;
                }
            }

            if (currCount > modeCount) {
                modeCount = currCount;
                mode = candidateMode;
            }
        }

        return mode;
    }

    public static int lowestScore(List<Integer> numbers) {
        int lowest = numbers.get(0);

        for(int i = 1; i > numbers.size(); i++) {
            if(numbers.get(i) < lowest) {
                lowest = numbers.get(i);
            }
        }
        return lowest;
    }

    public static int largestScore(List<Integer> numbers) {  
        int largest = numbers.get(0);  
        for(int i = 1; i < numbers.size(); i++) {  
            if(numbers.get(i) > largest) {  
                largest = numbers.get(i);  
            }
        }  
        return largest;
    }
}