使用输入和输出流读取和写入文件：

//Coded By Anurag Goel
//Reading And Writing Files
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;


public class WriteAFile {
    public static void main(String args[]) {
        try {
            byte array [] = {'1','a','2','b','5'};
            OutputStream os = new FileOutputStream("test.txt");
            for(int x=0; x < array.length ; x++) {
                os.write( array[x] ); // Writes the bytes
            }
            os.close();

            InputStream is = new FileInputStream("test.txt");
            int size = is.available();

            for(int i=0; i< size; i++) {
                System.out.print((char)is.read() + " ");
            }
            is.close();
        } catch(IOException e) {
            System.out.print("Exception");
        }
    }
}

如果您希望获得相对轻松的体验，还可以查看Apache Commons IO包，更具体地说是FileUtils类。

永远不要忘记检查第三方库。用于日期操作的Joda Time、用于常见字符串操作的Apache Commons Lang StringUtils等可以使代码更可读。

Java是一种很棒的语言，但标准库有时有点低级。功能强大，但级别较低。

在Java8中，使用文件和路径，并使用trywithresources构造。

import java.io.BufferedWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;

public class WriteFile{
    public static void main(String[] args) throws IOException {
        String file = "text.txt";
        System.out.println("Writing to file: " + file);
        // Files.newBufferedWriter() uses UTF-8 encoding by default
        try (BufferedWriter writer = Files.newBufferedWriter(Paths.get(file))) {
            writer.write("Java\n");
            writer.write("Python\n");
            writer.write("Clojure\n");
            writer.write("Scala\n");
            writer.write("JavaScript\n");
        } // the file will be automatically closed
    }
}

Use:

try (Writer writer = new BufferedWriter(new OutputStreamWriter(new FileOutputStream("myFile.txt"), StandardCharsets.UTF_8))) {
    writer.write("text to write");
} 
catch (IOException ex) {
    // Handle me
}  

使用try（）将自动关闭流。此版本短、快（缓冲），并支持选择编码。

这个特性是在Java7中引入的。

以下是编写文件的代码，也在退出帮助内容网页时删除：

public String writeHelpContent(String filePath, String helpPageContent) throws IOException{
        logger.info("HowToUseRiskOfficeHelpService - writeHelpContent start");
        File file = new File(filePath);
        try(FileWriter fw = new FileWriter(file);){
            file.deleteOnExit();
            if(file.createNewFile()) {
                logger.info("HowToUseRiskOfficeHelpService - file created successfully");
            }else {
                logger.info("HowToUseRiskOfficeHelpService - file already exists");
            }
            fw.write(helpPageContent); 
            fw.flush();
        }

        return "Sucessfully write into help page file";
    }

package fileoperations;
import java.io.File;
import java.io.IOException;

public class SimpleFile {
    public static void main(String[] args) throws IOException {
        File file =new File("text.txt");
        file.createNewFile();
        System.out.println("File is created");
        FileWriter writer = new FileWriter(file);

        // Writes the content to the file
        writer.write("Enter the text that you want to write"); 
        writer.flush();
        writer.close();
        System.out.println("Data is entered into file");
    }
}