使用 text.io 的简单 java 方法

Question

如果有人可以帮我解决这个简单的任务，我将永远感激不尽！我对 Java 很陌生，不明白如何调试这个简单的代码。

我需要：

• 读取每行列出的冰淇淋风味的外部文件

• 计算冰淇淋的总数

• 数一数名为“草莓”的冰淇淋的数量

• 计算“草莓”冰淇淋的百分比

这是我到目前为止所得到的......

package icecreamcounter;

import java.io.*; //Import TextIO

public class IcecreamCounter {

public static void main(String[] args) {
    // Open file for reading; if it cannot be opened, end the program
         try {
     TextIO.readFile("icecream.dat");
  }
  catch (IllegalArgumentException e) {
     System.out.println("Can't open file \"icecream.dat\" for reading!");
     System.out.println("Please make sure the file is present before");
     System.out.println("running the program.");
     System.exit(1);  // Terminates the program.

     //read the file
     string flavor;
     int strawb; //Total number of strawberry icecreams
     int totalIcecream; // Total number of icecreams
     double percentageStrawb; //Percentage of icecreams which are strawberry

     strawb = 0;
     percentageStrawb = (totalIcecream - strawb)/totalIcecream;

     while (!TextIO.eof()) {  // process one line of data.
         flavor = TextIO.getlnString();  // Get the rest of the line.
         totalIcecream = totalIcecream + 1; // Add one to the count of total icecreams
         return totalIcecream;
         if (flavor.equals("Strawberry") { // If icecream name is strawberry 
             strawb=strawb+1;         //then add one to the count of strawberry
             return strawb;
         }
     }

     System.out.println("Total number of cones is" totalIcecream);
     System.out.println("Total number of strawberry cones is" strawb);
     System.out.println("Percentage of strawberry cones is" percentageStrawb);
  }
}

}

问题可能与读取文件部分有关，但当我尝试打印答案时，它也会在底部出现错误。另外，我是否必须返回例如“totalIcecream”的值才能稍后打印出来？任何帮助将不胜感激！

Answer 1

首先，在system.exit(1) 之后，关闭catch 块，因为之后的代码永远不会到达。

其次，在println中，应该是"this is some text" + somevariable

将字符串变量或数字添加到字符串需要加号。

Answer 2

我建议使用 NIO，对我来说它运行良好且易于理解，这是我使用 Java 的 NIO API 的方法（自 Java 1.5 起可用）

try {
        Path pathToMyTextFile = Paths.get("c:/data/icecream.dat");

        //Here you must use the Charset according to the encoding of your TEXT file (I use ISO_8859_1)
        List<String> linesInFile = Files.readAllLines(pathToMyTextFile, StandardCharsets.ISO_8859_1);

        int totalNumberOfIceCreams = linesInFile.size();
        String targetFlavor = "Strawberry";//I would like to handle this in a variable
        int numberOfTargetFlavor = 0;

        for (String iceCreamLine : linesInFile) {
            if (iceCreamLine.equals(targetFlavor)) {
                numberOfTargetFlavor++;
            }
        }

        //Here I calculate the percentage:
        double percentage = (numberOfTargetFlavor * 100) / totalNumberOfIceCreams;

        System.out.println("Total number of Ice Creams: " + totalNumberOfIceCreams);
        System.out.println("Total number of " + targetFlavor + " Ice Creams: " + numberOfTargetFlavor);
        System.out.println("Percentage of Ice Creams that are flavor " + targetFlavor + ": " + percentage + "%");

    } catch (IOException e) {
        //Control your exception here
        e.printStackTrace();
    }

我使用了一个名为“icecream.dat”的文件，该文件位于我的 c:/data 文件夹中。该文件的内容如下：

Strawberry
Chocolate
Strawberry
Orange
Cheese
Strawberry
Raspberry
Apple
Strawberry

我得到的输出是：

Total number of Ice Creams: 9
Total number of Strawberry Ice Creams: 4
Percentage of Ice Creams that are flavor Strawberry: 44.0%

我知道这不是 TextIO，但也是一个好方法。如果您必须使用 TextIO 进行练习，那么现在您有一种新方法，如果您将来需要它。

问候和快乐编码:)