Java 写入控制台和文件

我试图让java程序的输出写入文件

用户输入一些不应包含在文件中的数据。当程序响应时，它应该向用户输出信息，并将输出写入文件

从示例中，我开始在我的驾驶课程中使用以下内容：

static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
static String lineFromOutput;

此代码位于我可能从程序接收输出的每个位置：

try {
    lineFromInput = in.readLine();
    FileWrite.write(lineFromInput);
} catch (IOException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
}

其调用的类是：

public class FileWrite {
    public static void write(String message) { 
        PrintWriter out = null;
        try {
            out = new PrintWriter(new FileWriter("output.txt"), true);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        out.write(message);
        out.close();
    }
}

它创建输出文件，但仅此而已。程序的所有输出均未写入。 我已经看了很多例子，这似乎是最简单的方法让球滚动，虽然我愿意接受任何其他建议

---

谢谢

我认为应该是

InputStremReader

，在下面的语句中使用单个

t

：

static BufferedReader in= new BufferedReader(new OutputtStreamReader(System.in));
static String lineFromOutput;

作为

编辑：这很好用请确保通过输入控制台提供输入。另外请注意，它只能读写（覆盖）单行。

    public class FileWrite {
       public static void write(String message) { 
                PrintWriter out = null;
              try {
                  out = new PrintWriter(new FileWriter("output.txt"), true);
              } catch (IOException e) {
                  // TODO Auto-generated catch block
                  e.printStackTrace();
              }
                out.write(message);
                out.close();
        }

       public static void main(String[] args){
           String lineFromInput;
           try {
                BufferedReader in = new BufferedReader(
                                            new InputStreamReader(System.in));
                lineFromInput = in.readLine();
                FileWrite.write(lineFromInput);
                in.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
           }
       }
     }

编辑2:更新多行输入程序这不是每次编写时打开和关闭文件的最佳方式，但我只是想让您的程序进行一些小的更改。如果您需要避免重复打开/关闭输出文件的建议，请告诉我

变化亮点：

读取行，直到输入中接收到“退出”（根据需要更改单词）

在

append

模式下打开文件

public class FileWrite {
   public static void write(String message) { 
            PrintWriter out = null;
          try {
              out = new PrintWriter(new FileWriter("output.txt", true), true);
          } catch (IOException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
          }
            out.write(message);
            out.close();
    }

   public static void main(String[] args){
       String lineFromInput = "";
       try {
            System.out.println("Provide the inputs in any number of lines");
            System.out.println("Type \"exit\" in new line when done");
            BufferedReader in = new BufferedReader(
                                new InputStreamReader(System.in));
            while(!"exit".equals(lineFromInput)){
               lineFromInput = in.readLine();
               FileWrite.write(lineFromInput+System.lineSeparator());
            }
            in.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
       }
   }
 }

EDIT3:使用

Scanner

读取输入的更新程序：

        private static HashMap<Integer, Object> shapes = 
                                              new HashMap<Integer, Object>();
        static int i = 0;

        public static void main(String[] args) {
            PrintWriter output = null;
            Scanner scanner = new Scanner(System.in);
            try {
                output = new PrintWriter(new FileWriter("output.txt"), true);
            } catch (IOException e1) {
                System.err.println("You don't have accress to this file");
                System.exit(1);
            }
            String command = "";
            while(!"quit".equalsIgnoreCase(command)){
                System.out.println("Enter your Command: ");
                command = scanner.next();
                if (command.equalsIgnoreCase("create")) {
                    String type = scanner.next();
                    if (type.equalsIgnoreCase("line")) {
                        double length = scanner.nextDouble();
                        Line l = new Line(length);
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, l);
                        i++;
                    }else if (type.equalsIgnoreCase("circle")) {
                        double radius = scanner.nextDouble();
                        String color = scanner.next();
                        Circle c = new Circle(radius, Colors.valueOf(color));
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, c);
                        i++;
                    }else if (type.equals("rectangle")) {
                        double length = scanner.nextDouble();
                        double width = scanner.nextDouble();
                        String color = scanner.next();
                        Rectangle r = new Rectangle(length, width,
                        Colors.valueOf(color));
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, r);
                        i++;
                    }else if (type.equals("square")) {
                        double length = scanner.nextDouble();
                        String color = scanner.next();
                        Square s = new Square(length, Colors.valueOf(color));
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, s);
                        i++;
                    }
                }else if (command.equals("printbyperimeter")) {
                    Shape[] shapeArray = shapes.values().toArray(new Shape[0]);
                    Arrays.sort(shapeArray);
                            System.out.println("Print in ascending order...");
                    for (int j = 0; j < shapeArray.length; j++) {
                        Shape temp = shapeArray[j];
                        if (temp.getClass().getName().equals("Line")) {
                            System.out.println("Shape: " 
                                    + temp.getClass().getName() + ", Perimeter: "
                                    + temp.getPerimeter());
                                } else {
                            System.out.println("Shape: " 
                                    + temp.getClass().getName() + ", Color: "
                                    + ((Colorable) temp).getColor()
                                    + ", Perimeter: " + temp.getPerimeter());
                                }
                            }
                }else if (command.equals("printbyarea")) {
                    Shape[] shapeArray = shapes.values().toArray(new Shape[0]);
                    System.out.println("Print in random order...");
                    for (int j = 0; j < shapeArray.length; j++) {
                        Shape temp = shapeArray[j];
                        if (!temp.getClass().getName().equals("Line")) {
                            System.out.println("Shape: "
                                    + temp.getClass().getName() + ", Color: "
                                    + ((Colorable) temp).getColor() + ", Area: "
                                    + ((Areable) temp).getArea());
                                }
                        }
                }else if (command.equals("quit")) {
                    scanner.close();
                    System.exit(0);
                }
           }
           output.close();
        }

私有静态哈希映射形状=
新的HashMap（）；
静态int i=0；
公共静态void main（字符串[]args）{
PrintWriter输出=null；
扫描仪=新的扫描仪（System.in）；
试一试{
输出=新的PrintWriter（新的FileWriter（“output.txt”），true；
}捕获（IOE1异常）{
System.err.println（“您没有此文件的授权”）；
系统出口（1）；
}
String命令=”；
while（！“quit”.equalsIgnoreCase（命令））{
System.out.println（“输入命令：”）；
command=scanner.next（）；
if（command.equalsIgnoreCase（“创建”））{
字符串类型=scanner.next（）；
if（类型.equalsIgnoreCase（“行”））{
双倍长度=scanner.nextDouble（）；
l线=新线（长度）；
scanner.nextLine（）；//刷新上一行
字符串行=scanner.nextLine（）；
输出格式（“%s”，行）；
形状。放置（i，l）；
i++；
}else if（类型.equalsIgnoreCase（“圆圈”））{
双半径=scanner.nextDouble（）；
字符串颜色=scanner.next（）；
圆c=新圆（半径、颜色。值（颜色））；
scanner.nextLine（）；//刷新上一行
字符串行=scanner.nextLine（）；
输出格式（“%s”，行）；
形状。放置（i，c）；
i++；
}else if（type.equals（“矩形”））{
双倍长度=scanner.nextDouble（）；
双倍宽度=scanner.nextDouble（）；
字符串颜色=scanner.next（）；
矩形r=新矩形（长度、宽度、，
颜色（颜色）的值；
scanner.nextLine（）；//刷新上一行
字符串行=scanner.nextLine（）；
输出格式（“%s”，行）；
形状。放置（i，r）；
i++；
}else if（类型等于（“平方”））{
双倍长度=scanner.nextDouble（）；
字符串颜色=scanner.next（）；
正方形s=新正方形（长度、颜色。值（颜色））；
scanner.nextLine（）；//刷新上一行
字符串行=scanner.nextLine（）；
输出格式（“%s”，行）；
形状。放置（i，s）；
i++；
}
}else if（command.equals（“PrintByPermiture”））{
Shape[]shapeArray=shapes.values（）.toArray（新形状[0]）；
数组.sort（shapeArray）；
System.out.println（“按升序打印…”）；
对于（int j=0；j        private static HashMap<Integer, Object> shapes = 
                                              new HashMap<Integer, Object>();
        static int i = 0;

        public static void main(String[] args) {
            PrintWriter output = null;
            Scanner scanner = new Scanner(System.in);
            try {
                output = new PrintWriter(new FileWriter("output.txt"), true);
            } catch (IOException e1) {
                System.err.println("You don't have accress to this file");
                System.exit(1);
            }
            String command = "";
            while(!"quit".equalsIgnoreCase(command)){
                System.out.println("Enter your Command: ");
                command = scanner.next();
                if (command.equalsIgnoreCase("create")) {
                    String type = scanner.next();
                    if (type.equalsIgnoreCase("line")) {
                        double length = scanner.nextDouble();
                        Line l = new Line(length);
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, l);
                        i++;
                    }else if (type.equalsIgnoreCase("circle")) {
                        double radius = scanner.nextDouble();
                        String color = scanner.next();
                        Circle c = new Circle(radius, Colors.valueOf(color));
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, c);
                        i++;
                    }else if (type.equals("rectangle")) {
                        double length = scanner.nextDouble();
                        double width = scanner.nextDouble();
                        String color = scanner.next();
                        Rectangle r = new Rectangle(length, width,
                        Colors.valueOf(color));
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, r);
                        i++;
                    }else if (type.equals("square")) {
                        double length = scanner.nextDouble();
                        String color = scanner.next();
                        Square s = new Square(length, Colors.valueOf(color));
                        scanner.nextLine();//flush the previous line
                        String line = scanner.nextLine();
                        output.format("%s", line);
                        shapes.put(i, s);
                        i++;
                    }
                }else if (command.equals("printbyperimeter")) {
                    Shape[] shapeArray = shapes.values().toArray(new Shape[0]);
                    Arrays.sort(shapeArray);
                            System.out.println("Print in ascending order...");
                    for (int j = 0; j < shapeArray.length; j++) {
                        Shape temp = shapeArray[j];
                        if (temp.getClass().getName().equals("Line")) {
                            System.out.println("Shape: " 
                                    + temp.getClass().getName() + ", Perimeter: "
                                    + temp.getPerimeter());
                                } else {
                            System.out.println("Shape: " 
                                    + temp.getClass().getName() + ", Color: "
                                    + ((Colorable) temp).getColor()
                                    + ", Perimeter: " + temp.getPerimeter());
                                }
                            }
                }else if (command.equals("printbyarea")) {
                    Shape[] shapeArray = shapes.values().toArray(new Shape[0]);
                    System.out.println("Print in random order...");
                    for (int j = 0; j < shapeArray.length; j++) {
                        Shape temp = shapeArray[j];
                        if (!temp.getClass().getName().equals("Line")) {
                            System.out.println("Shape: "
                                    + temp.getClass().getName() + ", Color: "
                                    + ((Colorable) temp).getColor() + ", Area: "
                                    + ((Areable) temp).getArea());
                                }
                        }
                }else if (command.equals("quit")) {
                    scanner.close();
                    System.exit(0);
                }
           }
           output.close();
        }

public static void main(String[] args) {
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
String lineFromOutput;

try {
    lineFromOutput = in.readLine();
    FileWrite.write(lineFromOutput);
} catch (IOException e) {
// TODO Auto-generated catch block
 e.printStackTrace();
}



}

public static class FileWrite {
    private static void write(String message) throws IOException { 
      BufferedWriter out = null;
    try {
        out = new BufferedWriter(new FileWriter(new File("C:\\Users\\Teresa\\Dropbox\\output.txt")));
        //Replace the above line with your path.
        out.write(message);
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
      out.close();
    }
}