StringReader class

see Reader class for descriptions of StringReader's methods. They are:

.mark( readAheadLimit ) Mark the present position in the stream.

.markSupported( ) Tell whether this stream supports the mark(...) operation.

.read( ) Read a single character, returning it in the low end two bytes of an int.

.read( char[ ] ) Read characters into a char array.

.read( char[ ], offset, len) Read characters into a portion of a char array.

.ready( ) Tell whether this stream is ready to be read.

.reset( ) Reset the stream.

.skip( n ) Skip over n characters in the stream.

.close( ) Close the stream.

■ StringReader doesn’t add any methods to Reader's. But it lets you use Reader's methods to read a String from memory as if it were an I/O stream.

■ StringReader supports mark(...) and reset( ).

■ This snippet reads and prints just the first character of a String:

import java.io.*;

String s = "ABCDEF";

try {

StringReader sr = new StringReader( s );

System.out.println( (char) sr.read( )); // just one char is read here

}

catch (IOException e) { }

■ The above example does the same thing as the one above, but it explicitly shows the returned int. Again, just the first character is read.

import java.io.*;

String s = "ABCDEF";

try {

StringReader sr = new StringReader( s );

int x = 0;

x = sr.read( );

System.out.println( (char) x ); // just one char is read here

}

catch (IOException e) { }

■ This snippet reads the entire String in a single operation by determining its length first. Note that, since StringReader's constructor does not throw an IOException, it can be located outside the try-catch block.

import java.io.*;

String s = "ABCDEFGHIJK";

StringReader sr = new StringReader( s );

char[ ] c = new char[ s.length( ) ];

try {

sr.read( c ); // one statement reads the entire String here

for ( int x = 0; x < s.length( ); x++ ) {

System.out.print( c[x] );

}

} catch (IOException e) { }

■ This snippet reads the entire String, one character at a time, without knowing its length beforehand.

import java.io.*;

String s = "XYZ";

StringReader sr = new StringReader( s );

int x;

try {

while ( (x = sr.read( )) != -1 ) { // checks for normal end of stream here

System.out.print( (char) x );

}

} catch (IOException e) { }