用Java创建和写入(文本)文件的最简单方法是什么?
当前回答
要创建文件而不覆盖现有文件,请执行以下操作:
System.out.println("Choose folder to create file");
JFileChooser c = new JFileChooser();
c.setFileSelectionMode(JFileChooser.DIRECTORIES_ONLY);
c.showOpenDialog(c);
c.getSelectedFile();
f = c.getSelectedFile(); // File f - global variable
String newfile = f + "\\hi.doc";//.txt or .doc or .html
File file = new File(newfile);
try {
//System.out.println(f);
boolean flag = file.createNewFile();
if(flag == true) {
JOptionPane.showMessageDialog(rootPane, "File created successfully");
}
else {
JOptionPane.showMessageDialog(rootPane, "File already exists");
}
/* Or use exists() function as follows:
if(file.exists() == true) {
JOptionPane.showMessageDialog(rootPane, "File already exists");
}
else {
JOptionPane.showMessageDialog(rootPane, "File created successfully");
}
*/
}
catch(Exception e) {
// Any exception handling method of your choice
}
其他回答
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
}
}
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");
}
}
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";
}
请注意,下面的每个代码示例都可能引发IOException。为了简洁起见,省略了Try/catch/finally块。有关异常处理的信息,请参阅本教程。
请注意,如果文件已经存在,下面的每个代码示例都将覆盖该文件
创建文本文件:
PrintWriter writer = new PrintWriter("the-file-name.txt", "UTF-8");
writer.println("The first line");
writer.println("The second line");
writer.close();
创建二进制文件:
byte data[] = ...
FileOutputStream out = new FileOutputStream("the-file-name");
out.write(data);
out.close();
Java 7+用户可以使用Files类写入文件:
创建文本文件:
List<String> lines = Arrays.asList("The first line", "The second line");
Path file = Paths.get("the-file-name.txt");
Files.write(file, lines, StandardCharsets.UTF_8);
//Files.write(file, lines, StandardCharsets.UTF_8, StandardOpenOption.APPEND);
创建二进制文件:
byte data[] = ...
Path file = Paths.get("the-file-name");
Files.write(file, data);
//Files.write(file, data, StandardOpenOption.APPEND);
在Java 7及以上版本中:
try (Writer writer = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream("filename.txt"), "utf-8"))) {
writer.write("something");
}
但有一些有用的实用程序:
来自commons io的FileUtils.writeStringtoFile(..)来自番石榴的文件.write(..)
还要注意,您可以使用FileWriter,但它使用默认编码,这通常是一个坏主意-最好显式指定编码。
以下是Java 7之前的原始答案
Writer writer = null;
try {
writer = new BufferedWriter(new OutputStreamWriter(
new FileOutputStream("filename.txt"), "utf-8"));
writer.write("Something");
} catch (IOException ex) {
// Report
} finally {
try {writer.close();} catch (Exception ex) {/*ignore*/}
}
另请参阅:读取、写入和创建文件(包括NIO2)。
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