Question

我需要将那些System.out.printlns写入文本文件，但我不知道这是怎么发生的，所以我需要一些先进的人帮助。

  System.out.println("You have have entered "+EnteredNumbers+ " numbers!");
  System.out.println("You have have entered "+Positive+ " Positive numbers!");
  System.out.println("The Average of the Positive Numebers is "+AveragePositive+ "!");
  System.out.println("You have have entered "+Negative+ " Negative numbers!");
  System.out.println("The Sum of the Negative numbers is "+NegativeSum+ "!");

以下是整个代码：

import java.io.*; 

public class Nums { 
  public static void main(String args[]) 
    throws IOException 
  { 
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); 
    String str;
    int EnteredNumbers = -1;
    int Positive = 0;
    int Negative = 0;
    int NegativeSum = 0;
    int PositiveSum = 0; 
    double AveragePositive = 0;

    System.out.println("Enter '0' to quit."); 
    System.out.println("Enter Numbers: "); 
   try{
    do { 
      EnteredNumbers++;
      str = br.readLine();
      int num = Integer.parseInt(str);
      if (num>0)
      {
        Positive++;
        PositiveSum+=num;
      }
      else if (num<0)
      {
        Negative++;
        NegativeSum+=num;
      }
       } 
    while(!str.equals("0")); 
      AveragePositive = (double)PositiveSum/(double)Positive;  
      System.out.println("You have have entered "+EnteredNumbers+ " numbers!");
      System.out.println("You have have entered "+Positive+ " Positive numbers!");
      System.out.println("The Average of the Positive Numebers is "+AveragePositive+ "!");
      System.out.println("You have have entered "+Negative+ " Negative numbers!");
      System.out.println("The Sum of the Negative numbers is "+NegativeSum+ "!");

      }
    catch (java.lang.NumberFormatException ex)
    {
        System.out.println("Invalid Format!");
    }  
} 
}

我是初学者，我很乐意得到一些帮助！

Answer 1

System.out是写入标准输出的PrintStream。您需要创建一个FileOutputStream并使用PrintStream（或更好FileWriter PrintWriter）来装饰它：

File file = new File("C:/file.txt");
FileWriter fw = new FileWriter(file);
PrintWriter pw = new PrintWriter(fw);
pw.println("Hello World");
pw.close();

另见：

Which is the best way to create file and write to it in Java.

Answer 2

这是2014年。所以有java.nio.file。

因此：

final List<String> list = new ArrayList<>();

list.add("first string here");
list.add("other string");
// etc etc

然后：

final Path path = Paths.get("path/to/write/to");

Files.write(path, list, StandardCharsets.UTF_8, StandardOpenOption.CREATE);

don't use File。

Answer 3

你可以使用setOut（）方法将filewrite与System.out.println（）;在调用setOut（）之后每当使用System.out.println（）时，方法sop将打印在文件上或者你在setOut（）方法中给出的那个

将System.Out.Println写入文本文件

3 个答案: