Hướng dẫn và ví dụ Java Reader

public abstract class Reader implements Readable, Closeable

JP日本-八洲

public static Reader nullReader()   

public int read(java.nio.CharBuffer target) throws IOException  

public int read() throws IOException  

public int read(char cbuf[]) throws IOException  

public int read(char cbuf[], int off, int len) throws IOException  

public long skip(long n) throws IOException  

public boolean ready() throws IOException   

public boolean markSupported()  

public void mark(int readAheadLimit) throws IOException  

public void reset() throws IOException   

public void close() throws IOException  

public long transferTo(Writer out) throws IOException

public int read() throws IOException

package org.o7planning.reader.ex;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

public class Reader_read_ex1 {

    public static void main(String[] args) throws IOException {
        // StringReader is a subclass of Reader.
        Reader reader = new StringReader("JP日本-八洲");

        int charCode;
        while((charCode = reader.read()) != -1) {
            System.out.println((char)charCode + " " + charCode);
        }
        reader.close();
    }
}

public int read(char[] cbuf) throws IOException

package org.o7planning.reader.ex;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

public class Reader_read_ex2 {

    public static void main(String[] args) throws IOException {
        // StringReader is a subclass of Reader.
        Reader reader = new StringReader("123456789-987654321-12345");
 
        // Create a temporary char array.
        char[] temp = new char[10];
        int charCount = -1;
         
        while ((charCount = reader.read(temp)) != -1) {
            String s = new String(temp, 0, charCount);
            System.out.println(s);
        }
        reader.close();
    }
}

public int read(char[] cbuf, int offset, int len) throws IOException

public int read(java.nio.CharBuffer target) throws IOException

package org.o7planning.reader.ex;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.nio.CharBuffer;

public class Reader_read_ex3 {

    public static void main(String[] args) throws IOException {
        // StringReader is a subclass of Reader.
        Reader reader = new StringReader("123456789-987654321-12345");
 
        CharBuffer cb = CharBuffer.allocate(10);
    
        // Read for the first time
        reader.read(cb);
        System.out.println(cb.flip().toString());
        
        // Read for the second time
        reader.read(cb);
        System.out.println(cb.flip().toString());
        
        // Read for the third time.
        reader.read(cb);
        System.out.println(cb.flip().toString());
        
        reader.close();  
    }
}

public void close() throws IOException

public interface Closeable extends AutoCloseable

package org.o7planning.reader.ex;

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

public class Reader_close_ex1 {
    
    // Or Windows path: C:/Somefolder/utf8-file-without-bom.txt
    private static final String file_path = "/Volumes/Data/test/utf8-file-without-bom.txt";

    public static void main(String[] args) throws IOException {
        
        // (Reader class implements Closeable)
        // (Closeable interface extends AutoCloseable)
        // try block will automatically close stream for you.
        try (Reader fileReader= new FileReader(file_path)) {
            int code;
            while((code = fileReader.read()) !=  -1)  {
                System.out.println((char)code);
            }
        } // end try
    }
}

public long skip(long n) throws IOException

package org.o7planning.reader.ex;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

public class Reader_skip_ex1 {

    public static void main(String[] args) throws IOException {
        // StringReader is a subclass of Reader.
        Reader reader = new StringReader("123456789-987654321-ABCDE");

        int firstCharCode = reader.read();
        int secondCharCode = reader.read();

        System.out.println("First character: " + (char) firstCharCode);
        System.out.println("Second character: " + (char) secondCharCode);

        reader.skip(18); // Skips 18 characters.

        int code;
        while ((code = reader.read()) != -1) {
            System.out.println((char) code);
        }
        reader.close();
    }
}

// Java 10+
public long transferTo(Writer out) throws IOException

package org.o7planning.reader.ex;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.io.Writer;

public class Reader_transferTo_ex1 {

    public static void main(String[] args) throws IOException {
        // StringReader is a subclass of Reader.
        Reader reader = new StringReader("123456789-987654321-ABCDE");

        // Or Windows path: C:/Somepath/out-file.txt
        File file = new File("/Volumes/Data/test/out-file.txt");
        // Create parent folder.
        file.getParentFile().mkdirs();

        Writer writer = new FileWriter(file);

        reader.skip(10); // Skips 10 characters.

        reader.transferTo(writer);

        reader.close();
        writer.close();
    }
}

987654321-ABCDE

public boolean markSupported()

public void mark(int readAheadLimit) throws IOException

package org.o7planning.reader.ex;

import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;

public class Reader_mark_ex1 {

    public static void main(String[] args) throws IOException {
        // StringReader is a subclass of Reader.
        Reader reader = new StringReader("123456789-987654321-ABCDE");

        reader.skip(10); // Skips 10 characters.

        System.out.println("StringReader markSupported? " + reader.markSupported()); // true
        
        reader.mark(9);
        
        int code1 = reader.read();
        int code2 = reader.read();
        
        System.out.println((char) code1); // '9'
        System.out.println((char) code2); // '8'
        reader.skip(5);
        
        System.out.println("Reset");
        reader.reset(); // Return to the marked position.
        
        int code;
        while((code = reader.read())!= -1) {
            System.out.println((char)code);
        }
        reader.close();
    }
}

public void reset() throws IOException

public boolean ready() throws IOException