Java Java类

Java.io.LineNumberInputStream 类只是输入流的扩展，提供了一个额外的工具来保存当前行号的记录。

行是以 : '\r' 结尾的字节序列，即回车字符或字符：'\n'，或回车字符后面的字符。

宣言 ：

public class LineNumberInputStream
   extends Reader

构造函数：

LineNumberInputStream(InputStream in) : 
Constructs a newline no. stream that reads 
it's input from the specified Input Stream.

方法：

• read() : Java.io.LineNumberInputStream.read()从输入流中读取数据的下一个字节。它返回表示 '0 – 255' 范围内的字节的 int 值。它返回“-1”以指示输入流的结束。
  句法 ：

public int read()
Parameters : 
-------
Return : 
int value representing the bytes in the range of '0 - 255'.
return -1, indicating end of Input Stream.
Exception: 
IOException : in case I/O error occurs

执行 ：

Java

// Java program illustrating the working of read() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            // read() method returning Bytes of Input Stream as integer
            // '-1' indicating to read till end Of Input Stream
            while((a = geekline.read()) != -1)
            {
                // Since read() method returns Integer value
                // So, we convert each integer value to char
                c = (char)a;
                System.out.print(c);
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
       {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
以下Java代码不会在此处运行，因为我们无法访问在线 IDE 上的任何文件。
因此，将程序复制到您的系统并在那里运行它。

程序中使用的ABC.txt文件包含：

Hello
Geeks.
Explaining 
read() method

输出 ：

Hello
Geeks.
Explaining 
read() method

• getLineNumber() : Java.io.LineNumberInputStream.getLineNumber()返回当前行的编号。
  句法 ：

public int getLineNumber()
Parameters : 
-------
Return : 
no. of current line

执行 ：

Java

// Java program illustrating the working of getLineNumber() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try
           {
            char c;
            int a, b;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
                // So, we convert each integer value to char
                c = (char)a;
                 
                // Use of getLineNumber() : to print line no.
                a = geekline.getLineNumber();
                System.out.println(" At line : " + a);
                System.out.print(c);
 
            }
            a = geekline.getLineNumber();
            System.out.println(" at line: " + a);
 
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
        {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
以下Java代码不会在此处运行，因为我们无法访问在线 IDE 上的任何文件。
因此，将程序复制到您的系统并在那里运行它。

程序中使用的ABC.txt文件包含：

no. of
lines

输出 ：

At line : 0
n At line : 0
o At line : 0
. At line : 0
  At line : 0
o At line : 0
f At line : 1

 At line : 1
l At line : 1
i At line : 1
n At line : 1
e At line : 1
s at line: 1

• available() : Java.io.LineNumberInputStream.available()返回可以从输入流中读取而不阻塞的字节数。
  句法 ：

public int available()
Parameters : 
-------
Return : 
returns the no. of bytes that an be read from the Input Stream.
Exception: 
IOException : in case I/O error occurs

执行 ：

Java

// Java program illustrating the working of available() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a, b;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
              // So, we convert each integer value to char
                c = (char)a;
 
              // Use of available method : return no. of bytes that can be read
                a = geekline.available();
                System.out.println(c + " Bytes available : " + a);
 
            }
 
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
        {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
以下Java代码不会在此处运行，因为我们无法访问在线 IDE 上的任何文件。
因此，将程序复制到您的系统并在那里运行它。

程序中使用的ABC.txt文件包含：

available

输出 ：

a Bytes available : 4
v Bytes available : 3
a Bytes available : 3
i Bytes available : 2
l Bytes available : 2
a Bytes available : 1
b Bytes available : 1
l Bytes available : 0
e Bytes available : 0

• setLineNumber() : Java.io.LineNumberInputStream.setLineNumber(int arg)将行号分配给我们想要的参数。
  句法 ：

public void setLineNumber(int arg)
Parameters : 
arg : line number to assign
Return : 
void
Exception: 
-----

执行 ：

Java

// Java program illustrating the working of setLineNumber() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a, b = 0;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
                // So, we convert each integer value to char
                c = (char)a;
                 
                // Use of setLineNumber() : to set the line no.
                geekline.setLineNumber(100 + b);
 
                // getLineNumber() : returning the current line no.
                a = geekline.getLineNumber();
                System.out.println(c + " Line No. Set : " + a);
                b++;
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
        {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
以下Java代码不会在此处运行，因为我们无法访问在线 IDE 上的任何文件。
因此，将程序复制到您的系统并在那里运行它。

程序中使用的ABC.txt文件包含：

LineNumber

输出 ：

L Line No. Set : 100
i Line No. Set : 101
n Line No. Set : 102
e Line No. Set : 103
N Line No. Set : 104
u Line No. Set : 105
m Line No. Set : 106
b Line No. Set : 107
e Line No. Set : 108
r Line No. Set : 109

• skip() : Java.io.LineNumberInputStream.skip(long arg)从输入流数据中跳过并丢弃“arg”字节。 LineNumberInputStream 的 skip 方法创建一个字节数组，然后重复读取它，直到读取 n 个字节或到达流的末尾。
  句法 ：

public long skip(long arg)
Parameters : 
arg : no. of bytes of Input Stream data to skip.
Return : 
no. of bytes to be skipped
Exception: 
IOException : in case I/O error occurs

执行 ：

Java

// Java program illustrating the working of setLineNumber() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a, b = 0;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            while((a = geekline.read()) != -1)
            {
                // So, we convert each integer value to char
                c = (char)a;
 
                // skip() : to skip and discard 'arg' bytes
                // Here skip() will skip and discard 3 bytes.
                geekline.skip(3);
                System.out.println(c);
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally{
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
以下Java代码不会在此处运行，因为我们无法访问在线 IDE 上的任何文件。
因此，将程序复制到您的系统并在那里运行它。

程序中使用的ABC.txt文件包含：

Program
Explaining
Skip() method

输出： ”

P
r
E
a
n
k
)
t

• read() : Java.io.LineNumberInputStream.read(byte[] buffer, int offset, int maxlen)从输入流中读取最多 'maxlen' 个字节到字节中。
  句法 ：

public int read(byte[] buffer, int offset, int maxlen)
Parameters : 
buffer : buffer whose data to read
offset : starting offset of the data
maxlen : max. no. of bytes to read
Return : 
total no. of bytes, else return -1 if End of Input Stream is identified
Exception: 
IOException : in case I/O error occurs

执行 ：

Java

// Java program illustrating the working of read() method
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws IOException
    {
        // LineNumberInputStream & FileInputStream initially null
        LineNumberInputStream geekline = null;
        FileInputStream geekinput = null;
 
        try{
            char c;
            int a;
 
            // New InputStream : 'ABC' is created
            geekinput = new FileInputStream("ABC.txt");
            geekline = new LineNumberInputStream(geekinput);
 
            // read() method returning Bytes of Input Stream as integer
            // '-1' indicating to read till end Of Input Stream
            while((a=geekline.read())!=-1)
            {
                // Since read() method returns Integer value
                // So, we convert each integer value to char
                c = (char)a;
                System.out.print(c);
            }
        }
        catch(Exception e)
        {
            // In case of error
            e.printStackTrace();
            System.out.println("ERROR Occurs ");
        }
        finally
       {
            // Closing the streams, Once the End of Input Stream is reached
            if(geekinput != null)
                geekinput.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
以下Java代码不会在此处运行，因为我们无法访问在线 IDE 上的任何文件。
因此，将程序复制到您的系统并在那里运行它。

程序中使用的ABC.txt文件包含：

Read() method

该方法所做的是 offset = r 和 maxlen = 5... 所以 — 即 3 个偏移量，然后是 5 个字节，即 Read(，然后又是偏移量，所以 —
输出 ：

The number of char read: 5

---Read(--

• mark() : Java.io.LineNumberInputStream.mark(int arg)标记输入流的当前位置。它设置readlimit，即在标记位置无效之前可以读取的最大字节数。
  句法 ：

public void mark(int arg)
Parameters :
arg : integer specifying the read limit of the input Stream
Return : 
void

• reset() : Java.io.LineNumberInputStream.reset()由 mark() 方法调用。它将输入流重新定位到标记的位置。
  句法 ：

public void reset()
Parameters :
----
Return : 
void
Exception :
->  IOException : If I/O error occurs.

Java程序解释 LineNumberInputStream 类方法：reset() 和 mark()

Java

// Java program illustrating the working of LineNumberInputStream method
// mark() and reset()
 
import java.io.*;
 
public class NewClass
{
    public static void main(String[] args) throws Exception
    {
 
        LineNumberInputStream geekline = null;
        FileInputStream geek = null;
        try{
 
            geek = new FileInputStream("GEEKS.txt");
            geekline = new LineNumberInputStream(geek);
 
            // read() method : reading and printing Characters one by one
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
 
            // mark() : read limiting the 'geek' input stream
            geekline.mark(0);
 
            // skip() : it results in reading of 'e' in G'e'eeks
            geekline.skip(1);
            System.out.println("skip() method comes to play");
            System.out.println("mark() method comes to play");
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
            System.out.println("Char : " + (char)geekline.read());
 
            boolean check = geekline.markSupported();
            if(geekline.markSupported())
            {
                // reset() method : repositioning the stream to marked positions.
                geekline.reset();
                System.out.println("reset() invoked");
                System.out.println("Char : " + (char)geekline.read());
                System.out.println("Char : " + (char)geekline.read());
            }
            else
            {
                System.out.println("reset() method not supported.");
            }
 
            System.out.println("geekline.markSupported() supported reset() : "
                                                        + check);
 
        }
        catch(Exception except)
        {
 
            // in case of I/O error
            except.printStackTrace();
        }
        finally
        {
            // releasing the resources back to the GarbageCollector when closes
            if(geek != null)
                geek.close();
 
            if(geekline != null)
                geekline.close();
        }
    }
}

笔记 ：
此代码不会在在线 IDE 上运行，因为此处不存在此类文件。
您可以在您的系统上运行此代码以检查工作情况。

代码中使用的ABC.txt文件有

HelloGeeks

输出 ：

Char : H
Char : e
Char : l
skip() method comes to play
mark() method comes to play
Char : o
Char : G
Char : e
reset() method not supported.
geekline.markSupported() supported reset() : false