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BufferedReader inputStream = new BufferedReader(new FileReader(fileName));	
String line = "";
StringBuffer text = new StringBuffer();
while((line = inputStream.readLine()) != null){
	text.append(line +"\n");
}

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BufferedReader(Reader in, int sz) 

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#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>

std::stringstream buffer;               //!< string buffer (line by line)
std::vector<char> binBuffer;            //!< binary buffer

/*!
 * Line-by-line read -- adding to stringbuffer
 */
void bufferedReader( char* fileName )
{
        std::ifstream file( fileName );
        std::string line;
        while ( ! file.eof() )
        {
                std::getline( file, line );
                buffer << line << std::endl;
        }
        file.close();
}

/*!
 * Binary-at-once read -- adding to STL vector
 */
void binReader( char* fileName )
{
        std::ifstream binFile( fileName, std::ios::binary | std::ios::in );

        binFile.seekg( 0, std::ios::end );
        size_t binSize = binFile.tellg();
        binFile.seekg( 0, std::ios::beg );

        size_t buffPos = binBuffer.size();
        binBuffer.resize( buffPos + binSize );

        binFile.read( &(binBuffer[buffPos]), binSize );

        binFile.close();
}

/*!
 * argv[1] -> filename; argv[2] -> "1": stringstream, "2": binary STL vec
 */
int main( int, char** argv )
{
        if ( std::string( argv[2] ) == "1" )
        {
                for ( int i = 0; i < 100; ++i )
                {
                        bufferedReader( argv[1] );
                }
                std::cout << "[MAIN] total bytes added to buffer: " << buffer.str().length() << std::endl;
        }
        else if ( std::string( argv[2] ) == "2" )
        {
                for ( int i = 0; i < 100; ++i )
                {
                        binReader( argv[1] );
                }
                std::cout << "[MAIN] total bytes added to buffer: " << binBuffer.size() << std::endl;
        }

        return 0;
}

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$ wc ~/NLD/src/libnldtools/extern/tetgenio/tetgen.cxx
  34961  151648 1278017 /home/ulli/NLD/src/libnldtools/extern/tetgenio/tetgen.cxx

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$ time ./readfile /home/ulli/NLD/src/libnldtools/extern/tetgenio/tetgen.cxx 1
[MAIN] total bytes added to buffer: 127801800

real    0m9.885s
user    0m6.060s
sys     0m1.728s

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$ time ./readfile /home/ulli/NLD/src/libnldtools/extern/tetgenio/tetgen.cxx 2
[MAIN] total bytes added to buffer: 127801700

real    0m5.802s
user    0m1.803s
sys     0m1.812s