How to read file contents using FileReader and BufferedReader classes in Java

How Java uses the FileReader and BufferedReader classes to read file contents

In Java programming, we often need to read the contents of files. Java provides many classes and methods to implement this function, the most commonly used of which are the FileReader and BufferedReader classes.

The FileReader class is used to read character stream files, while the BufferedReader class is used to buffer character input streams, which can quickly read the contents of large files.

The following is a sample code for reading file content using the FileReader and BufferedReader classes:

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class FileReadExample {
    public static void main(String[] args) {
        try {
            // 创建一个FileReader对象，指定要读取的文件路径
            FileReader fileReader = new FileReader("example.txt");
            
            // 使用BufferedReader包装FileReader对象，提高读取效率
            BufferedReader bufferedReader = new BufferedReader(fileReader);
            
            String line;
            
            // 逐行读取文件内容，直到文件末尾
            while ((line = bufferedReader.readLine()) != null) {
                System.out.println(line);
            }
            
            // 关闭资源
            bufferedReader.close();
            fileReader.close();
            
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

In the above code, we first create a FileReader object and specify the file path to be read. Then, we use the BufferedReader class to wrap the FileReader object, which can improve reading efficiency.

Next, we use a while loop to read the file content line by line. The readLine() method will return a line of content in the file. When the end of the file is read, it will return null so that we can determine whether the loop is terminated.

Finally, we remember to close resources and release memory.

It should be noted that in the sample code, we use try-catch statements to handle exceptions that may occur. In practical applications, we should develop good exception handling habits to avoid program crashes.

In addition to reading the file content line by line, we can also use other methods to read the file. For example, the read() method can read one character at a time, or the read(char[] cbuf) method can be used to read it all at once. Multiple characters.

To summarize, using the FileReader and BufferedReader classes can easily read file contents. When reading large files, using the BufferedReader class can improve reading efficiency. How to choose the correct reading method according to actual needs can be used flexibly according to your own needs.

I hope the above content will help you understand how to use the FileReader and BufferedReader classes to read file contents.

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