How to read carriage return in java

In Java, a carriage return is usually represented by a newline character. In Windows systems, "\r\n" is used to represent carriage return and line feed, while in Unix/Linux systems, "\n" is used. When reading text that contains carriage returns, Java treats these characters as ordinary characters. You can use the BufferedReader or Scanner classes to read text from an input stream until a carriage return or line feed is encountered.

In Java, a carriage return is usually represented by a newline character. In Windows systems, carriage return and line feed are usually expressed as "\r\n" (i.e. carriage return character \r and line feed character \n), while in Unix/Linux systems, line feed is usually represented as "\n". When reading text that contains carriage returns, Java treats these characters as ordinary characters.

If you want to read from the input stream until you encounter a carriage return and newline character, you can use classes such as java.io.BufferedReader or java.util.Scanner to achieve this. Here is an example using BufferedReader:

java

##

import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
  
public class ReadUntilEnter {  
    public static void main(String[] args) {  
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));  
  
        try {  
            System.out.print("请输入一些文本，然后按回车结束：");  
            StringBuilder input = new StringBuilder();  
            String line;  
              
            // 读取每一行，直到没有更多输入  
            while ((line = reader.readLine()) != null) {  
                // 对于单行输入，通常readLine()会在遇到回车换行时停止读取  
                input.append(line).append("\n"); // 如果需要保留原始换行符，可以添加它  
                  
                // 如果你知道输入只有一行，可以直接读取这一行，不需要循环  
                // input.append(line);  
                  
                // 检查是否读到空行（即用户只按了回车）  
                if (line.isEmpty()) {  
                    break; // 如果是空行，就跳出循环  
                }  
            }  
  
            // 输出读取到的文本  
            System.out.println("你输入的文本是：");  
            System.out.println(input.toString());  
  
        } catch (IOException e) {  
            e.printStackTrace();  
        } finally {  
            try {  
                reader.close();  
            } catch (IOException e) {  
                e.printStackTrace();  
            }  
        }  
    }  
}

In this example , the readLine() method of BufferedReader will read a line of text until it encounters a carriage return and line feed character ("\r\n" in Windows, "\n" in Unix/Linux). If the user only presses Enter without entering other text, the readLine() method will return an empty string.

If you want to detect carriage returns or line feeds directly, you may need to read the input character by character, such as using the read() method of BufferedReader or the next() method of Scanner. Regular expression. But usually, the readLine() method is sufficient to handle most text input scenarios.

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