將System.Out.Println寫入文本文件

Question

我需要將這些System.out.printlns寫入文本文件，但我不知道如何發生這種情況，所以我需要一些高級的幫助。

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+ "!"); 

這裏是整個代碼：

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!"); 
    } 
} 
} 

我是初學者，我很想得到一些幫助！

Answer 1

System.out是寫入標準輸出的PrintStream。您需要創建一個FileOutputStream與PrintStream（或更好FileWriter與PrintWriter）裝飾它：

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

---

另見：

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

Answer 2

此爲2014年5 。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 

然後：

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

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

而且don't use File。

Answer 3

你可以使用setOut（）方法進行filewrite和System.out.println（）;在使用System.out.println（）後調用setOut（），那麼方法sop將打印在文件上或者您在setOut（）方法中輸出的方法