2021-08-29 IO流(MyBufferedReader)

自定义BufferedReader，模拟readLine方法

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

class MyBufferedReader {

    private FileReader fileReader;

    public MyBufferedReader(FileReader fileReader) {
        this.fileReader = fileReader;
    }

    public String myReadLine() throws IOException {
        StringBuilder builder = new StringBuilder();
        int ch;
        while ((ch = fileReader.read()) != -1) {
            if (ch == '\r') {
                continue;
            }
            if (ch == '\n') {
                return builder.toString();
            } else {
                builder.append((char) ch);
            }
        }

        if (builder.length() != 0) {
            return builder.toString();
        }

        return null;
    }

    public void myClose() throws IOException {
        fileReader.close();
    }

}

public class MyBufferedReaderDemo {

    public static void main(String[] args) throws Exception {
        FileReader fileReader = new FileReader("E:\\demo.txt");
        MyBufferedReader myBufferedReader = new MyBufferedReader(fileReader);
        String line;
        if ((line = myBufferedReader.myReadLine()) != null) {
            System.out.println(line);
        }
        myBufferedReader.myClose();
    }

}