程序员在使用需要读写文件的 Java 应用程序时使用 Java 中的文本文件。 文本文件是存储信息、代码或任何其他数据的通用方式。文本文件被视为水平组织的字符序列。 Java 中的文本文件具有扩展名，例如包含 Java 代码的 .java。 Java 提供了不同的实用程序，允许您通过读取或写入纯文本文件来处理它们。您可以根据您的理解选择任何读/写实用程序。
在开始使用这些方法之前，我们正在考虑路径“/Users/praashibansal/Desktop/Data/test.txt”处的文本文件“test.txt”，其内容为“Hello，there”。
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代码：
import java.io.*;
public class BReader {
public static void main(String[] args) throws Exception
{
File f = new File(
"https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
// Creating an object
BufferedReader b
= new BufferedReader(new FileReader(f));
// Declaring a string variable
String s;
// Condition holds till
// there is a character in a string
while ((s = b.readLine()) != null)
// Print the string
System.out.println(s);
}
}输出：
代码：
import java.io.*;
public class RFile {
public static void main(String[] args) throws Exception
{
// Passing the file’s path
FileReader f = new FileReader(
"https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
// declaring loop variable
int i;
while ((i = f.read()) != -1)
// Print the content of a file
System.out.print((char)i);
}
}输出：
代码：
import java.io.File;
import java.util.Scanner;
public class ReadScan
{
public static void main(String[] args) throws Exception
{
// passing the file’s path
File file = new File("https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
Scanner s = new Scanner(file);
while (s.hasNextLine())
System.out.println(s.nextLine());
}
}输出：
代码：
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
public class FCExample {
public static void main(String[] args) {
Path path = Paths.get("https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
try {
byte[] b = Files.readAllBytes(path);
System.out.println("Read bytes: \n"+new String(b));
} catch (IOException e) {
}
}
}输出：
Code:
import java.io.FileWriter;
public class FWFile {
public static void main(String args[]){
try{
FileWriter f=new FileWriter("https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
f.write("Hello");
f.close();
}
catch(Exception e)
{
System.out.println(e);
}
System.out.println("Hello");
}
}Output:
Code:
import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.IOException;
public class BRExample {
public static void main(String args[]) {
String data = "data for output file";
try {
// Creates a FileWriter
FileWriter file = new FileWriter("https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
try ( // Creates a BufferedWriter
var o = new BufferedWriter(file)) {
// Writes the string to the file
o.write(data);
}
}
catch (IOException e) {
e.getStackTrace();
}
}
}Output:
Code:
import java.io.FileOutputStream;
import java.io.IOException;
public class GFG {
public static void main(String[] args)
{
String f = "Hello";
FileOutputStream o = null;
// starting Try block
try {
// creating an object of FileOutputStream
o = new FileOutputStream("https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
// storing byte content from string
byte[] str = f.getBytes();
// writing into the file
o.write(str);
// printing success message
System.out.print(
"data added successfully.");
}
// Catch block for exception handling
catch (IOException e) {
System.out.print(e.getMessage());
}
finally {
// closing the object
if (o != null) {
// checking if the file is closed
try {
o.close();
}
catch (IOException e) {
// showing exception message
System.out.print(e.getMessage());
}
}
}
}
}Output:
Code:
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
/**
* Java Files write file example
*
* @author pankaj
*
*/
public class FCExample {
public static void main(String[] args) {
Path path = Paths.get("https://cdn.educba.com/Users/praashibansal/Desktop/Data/test.txt");
try {
String str = "Example";
byte[] bs = str.getBytes();
Path w = Files.write(path, bs);
System.out.println("Written content in file:\n"+ new String(Files.readAllBytes(w)));
} catch (IOException e) {
}
}
}Output:
Reading and writing a file in Java is a straightforward process. With the availability of different methods and utilities in Java, you can choose a specific way to read from and write to a file. Each utility has its functionality that makes it different from others.
Answer: To read, you can use Reader Class or utility class. Some utility classes are- File Class, FileReader, BufferedReader, and Scanner class.
Answer: To write a file in Java, you can use FileWriter, BufferedWriter, java 7 Files, FileOutputStream, and many other methods.
Answer: You can easily import the File class from the java.io package to work with files.
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