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Message:

RE: Arrays

Posted by Kishori Sharan on August 03, 2000 at 3:59 PM

Hi
Here is what I understand from you question. You have a text file which consists of 7 columns and many rows. The column contains numeric values and you want to read them in java program so that you can use them. I have writtem a program with the following assumptions:
1. You have a text file with 7 columns.
2. Each row is separated by new line.
3. Each column value is separated by tab.
The program reads all the values in a two dimensional double array ( here it also prints the value on console. ) . I am also giving you the file contents ( for points.txt ).

Thanx
Kishori

////////////// Program Points.java ////////////
import java.util.* ;
import java.io.* ;
import java.text.* ;
public class Points {

private double[] parseStr ( String str ) {
double[] nums = new double[7] ;
DecimalFormat df = new DecimalFormat ( "0.00" ) ;
Number n = null;
String temp;
int counter = 0 ;
int start = 0;
int end = 0 ;

if ( str == null )
return nums ;

// Find the first position of tab
end = str.indexOf ( '\t', start ) ;
while ( end > 0 ) {

// Get the string between the start and end position
temp = str.substring ( start, end ) ;
try {
n = df.parse ( temp ) ;
if ( counter < nums.length )
nums[counter++] = n.doubleValue ( );

} catch ( Exception e ) {
}

// Read the next number
start = end + 1 ;
end = str.indexOf ( '\t', start ) ;
}

// Read the last number
start = str.lastIndexOf ( "\t" ) + 1 ;
end = str.length() ;

// Get the string between the start and end position
temp = str.substring ( start, end ) ;
try {
n = df.parse ( temp ) ;
if ( counter < nums.length )
nums[counter++] = n.doubleValue ( );

} catch ( Exception e ) {
}

return nums ;
}

public static void main ( String[] args ) throws Exception {
int rows = 0 ;
int rowCounter = 0 ;
Points nn = new Points () ;
BufferedReader br = new BufferedReader ( new InputStreamReader
( new FileInputStream ( "C:\\kishori\\points.txt" ) ) );

// Read total number of lines in file
String str = br.readLine ( );
while ( str != null ) {
rows++ ;
str = br.readLine ( );
}
rows-- ; // Decrement by one because rows is incremented by one after reading the line
double[][] points = new double[rows][7] ;

br.close () ;
br = new BufferedReader ( new InputStreamReader ( new FileInputStream ( "C:\\kishori\\points.txt" ) ) );

do {
// Read the first line
str = br.readLine ( );

// Parse the first line read
if ( rowCounter < rows && str != null )
points[rowCounter++] = nn.parseStr ( str ) ;

} while ( str != null ) ;

for ( int i = 0 ; i < points.length ; i ++ ) {
for ( int j = 0; j < points[i].length ; j++ )
System.out.print ( points[i][j] + "\t" );

System.out.println ();
}

// Close the stream
br.close ( );
}

}

//////////////////////// points.txt ////////////////////
100.11 100.12 100.13 100.14 100.15 100.16 100.17
200.11 200.12 200.13 200.14 200.15 200.16 200.17
300.11 300.12 300.13 300.14 300.15 300.16 300.17
400.11 400.12 400.13 400.14 400.15 400.16 400.17
500.11 500.12 500.13 500.14 500.15 500.16 500.17