STACK in JAVA

import java.io.BufferedReader; import java.io.BufferedWriter; import java.io.FileReader; import java.io.FileWriter; import java.io.IOException; import java.io.PrintWriter; import java.util.StringTokenizer;

/** * Read a .dat file and reverse it. * CPS 350 */ public class Reverse { public static void main(String[]args) { if (args.length != 3) { System.err.println(" Incorrect number of arguments"); System.err.println(" Usage: "); System.err. println("\tjava Reverse <stack type> <input file> <output file>");

System.exit(1); }

boolean useList = true; if (args[0].compareTo("list")==0) useList = true; else if (args[0].compareTo("array")==0) useList = false; else { System.err.println("\tSaw "+args[0]+" instead of list or array as first argument"); System.exit(1); }

try { // // Set up the input file to read, and the output file to write to // BufferedReader fileIn = new BufferedReader(new FileReader(args[1])); PrintWriter fileOut = new PrintWriter(new

BufferedWriter(new FileWriter(args[2])));

// // Read the first line of the .dat file to get sample rate.

// We want to store the sample rate value in a variable, // but we can ignore the "; Sample Rate" part of the line. // Step through the first line one token (word) at a time // using the StringTokenizer. The fourth token is the one // we want (the sample rate).

// StringTokenizer str; String oneLine; int sampleRate; String strJunk;

oneLine = fileIn.readLine();

str = new StringTokenizer(oneLine); strJunk = str.nextToken(); // Read in semicolon strJunk = str.nextToken(); // Read in "Sample" strJunk = str.nextToken(); // Read in "Rate"

// Read in sample rate sampleRate = Integer.parseInt(str.nextToken());

// // Read in the remainder of the file on line at a time. // The values in the first column are thrown away.

// Place values from the second column on the stack. // Stop reading if we reach the end of the file. //

DStack s; if (useList) s = new ListStack(); else s = new ArrayStack(); String timestep; double data;

int count = 0; while ((oneLine = fileIn.readLine()) != null) { if (oneLine.charAt(0) == ';') { continue; } str = new StringTokenizer(oneLine);

// Read in time step value from first column timestep = str.nextToken();

// Read in data value from second column data = Double.parseDouble(str.nextToken()); s.push(data); count++; }

System.out.println(count+" samples in file");

// // Print the data values to output .dat file. // First, output the header line: // "; Sample Rate <sample rate>" // fileOut.println("; Sample Rate " + sampleRate);

// Since the first column consists of numbers which start // at 0 and increase by 1/sampleRate every time slice, we'll // just use numSteps to recalculate these numbers. int numSteps = 0;

// Finally, we print the values in reverse order (by popping // them off the stack). The first column consists of numbers // which start at 0 and increase by 1/sampleRate per row, so // we'll use numSteps/sampleRate to recalculate the appropriate // values. Print a tab for uniform spacing.

while (!s.isEmpty()) { fileOut.println((double) numSteps / sampleRate + "\t" + s.pop()); numSteps++; }

// // Close the files // fileIn.close(); fileOut.close();

} catch(IOException ioe) { System.err. println ("Error opening/reading/writing input or output file."); System.exit(1); } catch(NumberFormatException nfe) { System.err.println(nfe.toString()); System.err.println("Error in file format"); System.exit(1); }

} }