声明方法和返回值

Question

我有一个完整的程序，但不确定如何在主程序中调用该方法？我的返回值需要是：

(word + " appears " + count + " times " );

和

("The average score for reviews containing the word horrible is " + average);

所有代码都需要保留在 methodOne 中。我只需要知道，如何调用该方法并返回正确的值？

注意：我非常是 Java 新手，所以请不要使用复杂的想法

当前代码： 导入 java.util.Scanner； 导入java.io.File； 导入 java.io.FileNotFoundException;

public class ReactionAnalysis {
  public static void main (String [] args)
  {
    System.out.println("Call Method One:");

  }


  public static String methodOne() throws FileNotFoundException
  {

Scanner keyboardInput = new Scanner(System.in);
System.out.println("Enter a word: ");
String word = keyboardInput.next();

File inputFile = new File("movieReviews.txt");
Scanner movieReview = new Scanner(inputFile);

String reviewText;
int reviewScore;
int count = 0;
double total = 0;

while (movieReview.hasNext())
{
  reviewScore = movieReview.nextInt();
  reviewText = movieReview.nextLine();

  if (reviewText.contains(word))
  {
    count++;
    total = total + reviewScore;
  }

}
    String str = (word + " appears " + count + " times " );
    double average = (total / count );
    String str2 = ("The average score for reviews containing the word horrible is " + average);
    return str + str2;
}
}

Answer 1

实际上并没有用于将代码放入方法的模板...您只需让方法返回您想要的内容，并尽可能高效地做到这一点。

您可以返回多个值的一种方法是返回一个数组（或者您可以使用ArrayList，但在这种情况下这将是矫枉过正。）您可以在方法内进行所有计算，当一切都说了并完成返回包含您希望它们的Strings 的数组。例如：

import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;
public class methodOne {
    public static void main(String[] args) {
        Scanner keyboardInput = new Scanner(System.in);
        System.out.println("Enter a word: ");
        String word = keyboardInput.next();

        File inputFile = new File("movieReviews.txt");

        String[] data = wordCount(word, inputFile);

        for(int i =0; i < data.length; i++) {
            System.out.println(data[i]);
        }
    }

    public static String[] wordCount(String word, File inputFile) {
        String[] results = new String[2];
        Scanner movieReview = null;
        try {
            movieReview = new Scanner(inputFile);
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            return null;
        }

        String reviewText;
        int reviewScore;
        int count = 0;
        double total = 0;

        while (movieReview.hasNext()) {
            reviewScore = movieReview.nextInt();
            reviewText = movieReview.nextLine();
            if (reviewText.contains(word)) {
                count++;
                total = total + reviewScore;
            }
        }

        double average = total/count;
        results[0] = word + " appears " + count + " times";
        results[1] = "The average score for reviews containing the word" + word + " is " + average;
        return results;
    }
}

如果您有任何问题，请随时告诉我！

Answer 2

将值传递给方法相当简单。例如：

    public class NewClass {
    public static void main(String[] args) {
        // passing two literal strings into the method
        // and then invoking it
        System.out.println(strCombo("Hello, ", "world!"));             
    }

    // if you are going to call a method in main, it must be static
    public static String strCombo(String str, String str2) {        
        return str + str2;
    }
} 

这适用于任何数据类型，如果它不返回任何内容，您只需将其设置为正确的或 VOID。

希望这会有所帮助！

Answer 3

有很多方法可以改进此代码，但为了使其简单而有用，我建议您：

• 创建一个方法来封装你的整个逻辑：readReviews();
• 让此方法返回一个包含 2 条预期行的数组；
• 从你的 main 中调用方法：String[] result = program.readReviews();（我建议使用 Result 对象，但不适合 OP）；
• 遍历结果以打印每一行。

完整代码：

public class methodOne {
    public static void main(String[] args) throws FileNotFoundException {
        methodOne methodOne = new methodOne();
        String[] result = methodOne.readReviews();
        
        for(String res: result){
            System.out.println(res);
        }

    }
    
    public String[] readReviews() throws FileNotFoundException{
        Scanner keyboardInput = new Scanner(System.in);
        System.out.println("Enter a word: ");
        String word = keyboardInput.next();

        File inputFile = new File("movieReviews.txt");
        Scanner movieReview = new Scanner(inputFile);

        String reviewText;
        int reviewScore;
        int count = 0;
        double total = 0;

        while (movieReview.hasNext()) {
            reviewScore = movieReview.nextInt();
            reviewText = movieReview.nextLine();

            if (reviewText.contains(word)) {
                count++;
                total = total + reviewScore;
            }
        }
        
        double average = (total / count);
        return new String[]{ 
                word + " appears " + count + " times ", 
                "The average score for reviews containing the word horrible is " + average};
    }
}