我正在尝试创建一个执行时间表的程序，并将其输出到名为log.txt的文件作为日志文件，但是当我运行它时它所做的只是运行并执行时间表和制作文件，但不向文件写入任何内容。有人可以告诉我，我的代码有什么问题吗？如果你这样做，谢谢。
键：
下载链接： - http://wardogsk93-ftp.bugs3.com/Downloads/Java/Counter/
Java Doc： - http://wardogsk93-ftp.bugs3.com/Downloads/Java/Counter/Java%20Doc/
Main.java： -
public class Main {
/************************************************/
/*************STUFF YOU CAN CHANGE***************/
/************************************************/
/** change this to start at a different number must be a number {@link Integer}**/
public static int minCount = 1;
/** change to change the number of where the programme will end must be a number {@link Integer}**/
public static int maxCount = 10;
/** change this to how many times you want to sleep for in seconds (1 = 1 second, 2 = 2 second, 10 = 10 second) before moving to next sum must be a number {@link Integer} **/
public static int sleepAmountMultiplyer = 1;
/** true = outputs to the command prompt / false = outputs to eclipse console {@link boolean}**/
public static boolean outputTOCMD = true;
/************************************************/
/******DONT CHANGE ANYTHING BELOW THIS LINE******/
/************************************************/
/** allows to output to a command prompt **/
private static Console cmd;
private static Output file;
private static int endNumber = maxCount + 1;
private static int sleepAmount = 1000 * sleepAmountMultiplyer;
/**
* main method
* call this to start
**/
public static void start() {
file = new Output();
if (outputTOCMD) {
cmd = new Console();
count();
cmd.exit();
} else {
count();
System.exit(1);
}
}
public static Main getInstance() {
return Main.getInstance();
}
/**code to start running**/
private static void count() {
try {
for (int i = minCount; i < maxCount + 1; i++) {
int j = i * i;
Thread.sleep(sleepAmount);
if (i == endNumber) {
return;
}
if (outputTOCMD) {
cmd.out(i + " X " + i + " = " + j);
file.write(String.valueOf(i) + " X " + String.valueOf(i) + " = " + String.valueOf(j));
} else {
System.out.println(i + " X " + i + " = " + j);
file.write(String.valueOf(i) + " X " + String.valueOf(i) + " = " + String.valueOf(j));
}
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
Output.class： -
import java.io.*;
public class Output {
public Output() {}
private Console cmd;
private File logFile;
private String input;
private BufferedReader reader;
private BufferedWriter writer;
public Output(Console cmd, File logFile, BufferedReader reader, BufferedWriter writer) {
this.cmd = cmd;
this.logFile = logFile;
this.reader = reader;
this.writer = writer;
}
/** writes to a log file using {@link FileWriter} **/
public void write(String message) {
try {
logFile = new File("log.txt");
writer = new BufferedWriter(new FileWriter(logFile));
if (!logFile.exists()) {
writer.write(message);
writer.close();
} else {
read();
if (logFile.isFile()) {
logFile.delete();
writer.write(message);
}
}
} catch (IOException e) {
if (Main.outputTOCMD) {
cmd.out(e.getMessage());
} else {
e.printStackTrace();
}
}
}
/** writes to a log file using {@link FileReader} **/
public void read() {
try {
logFile = new File("log.txt");
reader = new BufferedReader(new FileReader(logFile));
if (logFile.exists()) {
setInput(reader.readLine());
}
} catch (IOException e) {
if (Main.outputTOCMD) {
cmd.out(e.getMessage());
} else {
e.printStackTrace();
}
}
}
/**
* @return the input
*/
private String getInput() {
return input;
}
/**
* @param input the input to set
*/
private String setInput(String input) {
this.input = input;
return input;
}
}
Console.class： -
import java.awt.Color;
import java.awt.Image;
import java.net.MalformedURLException;
import java.net.URL;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JTextArea;
/**
* Creates the command prompt window in class {@link Console}
*/
public class Console {
private JFrame frame;
private JTextArea console;
private Image icon;
public Console() {
try {
frame = new JFrame();
frame.setBackground(Color.BLACK);
frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setName("Commad Prompt");
frame.setSize(678, 340);
frame.setTitle(frame.getName());
frame.setVisible(true);
icon = new ImageIcon(new URL("http://upload.wikimedia.org/wikipedia/en/e/ef/Command_prompt_icon_(windows).png")).getImage();
frame.setIconImage(icon);
console = new JTextArea();
console.setAutoscrolls(true);
console.setBackground(Color.BLACK);
console.setEditable(false);
console.setForeground(Color.WHITE);
console.setSelectionColor(Color.WHITE);
console.setSelectedTextColor(Color.BLACK);
console.setVisible(true);
frame.add(console);
} catch (MalformedURLException e) {
e.printStackTrace();
}
}
/**
* @param {@link String} text does the same as {@link System}.out.println();
*/
public void out(String text) {
console.append(text + "\n");
}
/**
* @exception {@link Exception} to catch any errors and prints them to the window
* does the same has {@link System}.exit(1);
*/
public void exit() {
try {
Thread.sleep(1000 * Main.sleepAmountMultiplyer);
console.disable();
frame.dispose();
System.exit(1);
} catch (Exception e) {
this.out(e.getMessage());
}
}
/**
* @return Allows you to acces all the stuff in <br>{@link Console}</br>
**/
public Console getInstance() {
return this;
}
}
Launch File:-
public class Test {
public static void main(String[] args) {
Main.minCount = 1;
Main.maxCount = 10;
Main.sleepAmountMultiplyer = 1;
Main.outputTOCMD = true;
Main.start();
}
}
答案 0 :(得分：2)
完成写入文件后，必须始终使用close()方法。否则它不会保存它（you also want to close to avoid resource leak errors...read here）。所以在这个方法中：
public void write(String message) {
try {
logFile = new File("log.txt");
writer = new BufferedWriter(new FileWriter(logFile));
if (!logFile.exists()) {
writer.write(message);
writer.close();
} else {
read();
if (logFile.isFile()) {
logFile.delete();
writer.write(message);
}
}
//close the buffer writer in order to save
writer.close();
} catch (IOException e) {
if (Main.outputTOCMD) {
cmd.out(e.getMessage());
} else {
e.printStackTrace();
}
}
}
或者，您可以在finally块中关闭。阅读完毕后，您还必须关闭BufferReader。如果您计划对同一文件进行多次Thread读/写，则在使用Thread时需要非常小心。
注意：每次都会覆盖该文件。但是，如果您想 追加 数据，请更改此行：
writer = new BufferedWriter(new FileWriter(logFile));
要：
writer = new BufferedWriter(new FileWriter(logFile, true));
FileWriter中的第二个参数确认您是要覆盖文件还是附加到文件。看看这个example。