我认为它应该在InputStremReader下面t的声明中使用：
static BufferedReader in= new BufferedReader(new OutputtStreamReader(System.in));
static String lineFromOutput;
作为
static BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
static String lineFromOutput;
编辑：这很好用。请确保您通过输入控制台提供输入。另请注意，它仅读取和写入（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： 更新了多线输入的程序。它不是每次写入文件时打开和关闭文件的最佳方式，但我只是想让您的程序通过细微的更改即可工作。如果您需要建议以避免重复打开/关闭输出文件，请告诉我。
变化亮点：
- 读取行直到在输入中接收到“exit”（根据需要更改单词）
append以模式打开文件。
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：您更新的程序Scanner用于读取输入：
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();
}