I'm trying to read a text file to get a version number but for some reason no matter what I put in the text file it always returns 0 (zero).
The text file is called version.txt and it contains no spaces or letters, just 1 character that is a number. I need it to return that number. Any ideas on why this doesn't work?
static int i;
public static void main(String[] args) {
String strFilePath = "/version.txt";
try
{
FileInputStream fin = new FileInputStream(strFilePath);
DataInputStream din = new DataInputStream(fin);
i = din.readInt();
System.out.println("int : " + i);
din.close();
}
catch(FileNotFoundException fe)
{
System.out.println("FileNotFoundException : " + fe);
}
catch(IOException ioe)
{
System.out.println("IOException : " + ioe);
}
}
private final int VERSION = i;
Here is the default solution that i use whenever i require to read a text file.
public static ArrayList<String> readData(String fileName) throws Exception
{
ArrayList<String> data = new ArrayList<String>();
BufferedReader in = new BufferedReader(new FileReader(fileName));
String temp = in.readLine();
while (temp != null)
{
data.add(temp);
temp = in.readLine();
}
in.close();
return data;
}
Pass the file name to readData method. You can then use for loop to read the only line in the arraylist, and can use the same loop to read multiple lines from different file...I mean do whatever you like with the arraylist.
Please don't use a DataInputStream
Per the linked Javadoc, it lets an application read primitive Java data types from an underlying input stream in a machine-independent way. An application uses a data output stream to write data that can later be read by a data input stream.
You want to read a File (not data from a data output stream).
Please do use try-with-resources
And since you seem to want an ascii integer, I'd suggest you use a Scanner.
public static void main(String[] args) {
String strFilePath = "/version.txt";
File f = new File(strFilePath);
try (Scanner scanner = new Scanner(f)) {
int i = scanner.nextInt();
System.out.println(i);
} catch (Exception e) {
e.printStackTrace();
}
}
Use an initializing block
An initializing block will be copied into the class constructor, in your example remove public static void main(String[] args), something like
private int VERSION = -1; // <-- no more zero!
{
String strFilePath = "/version.txt";
File f = new File(strFilePath);
try (Scanner scanner = new Scanner(f)) {
VERSION = scanner.nextInt(); // <-- hope it's a value
System.out.println("Version = " + VERSION);
} catch (Exception e) {
e.printStackTrace();
}
}
Extract it to a method
private final int VERSION = getVersion("/version.txt");
private static final int getVersion(String strFilePath) {
File f = new File(strFilePath);
try (Scanner scanner = new Scanner(f)) {
VERSION = scanner.nextInt(); // <-- hope it's a value
System.out.println("Version = " + VERSION);
return VERSION;
} catch (Exception e) {
e.printStackTrace();
}
return -1;
}
or even
private final int VERSION = getVersion("/version.txt");
private static final int getVersion(String strFilePath) {
File f = new File(strFilePath);
try (Scanner scanner = new Scanner(f)) {
if (scanner.hasNextInt()) {
return scanner.nextInt();
}
} catch (Exception e) {
e.printStackTrace();
}
return -1;
}
Related
in the assignment, the code is suppose to print on a single word from each file that repeats the most. I used a path to get to the list of files used for this assignment and i put them into an array. i cannot seems to find the problem as the array has all the files in it set to string. So why cant it find my file?
below is my code for single thread:
import java.io.*;
import java.util.*;
public class SingleThreaded {
public static void main(String[] args) throws IOException {
File directoryPath = new File("C:\\assignment 3\\links");
String[] dir = directoryPath.list();
System.out.println(Arrays.toString(dir));
String result;
//Scanner scan;
//try{
//Scanner scan = new Scanner(System.in);
long startTime = System.nanoTime();
for (String file : dir) {
//if(file.isFile()){
//BufferedReader inputStream = null;
String line;
//int i;
try{
//inputStream = new BufferedReader(new FileReader(file));file
Scanner scan = new Scanner(new File(file));
HashMap<String, Integer> map = new HashMap<>();
while (scan.hasNextLine()){
line = scan.nextLine().replaceAll("\\p{Punct}", " ");
String[] word = line.split("\s+");
for (int i = 0; i < word.length; i++) {
String string = word[i].toLowerCase();
if (string.length() >= 5) {
if (map.containsKey(string)) {
map.put(string, map.get(string) + 1);
} else {
map.put(string, 1);
}
}
}
}
result = Collections.max(map.entrySet(), Comparator.comparingInt(Map.Entry::getValue)).getKey();
System.out.println( file + ": " + result);
}catch (FileNotFoundException e) {
e.printStackTrace();
}
/* }finally{
if(inputStream != null){
inputStream.close();
}
}
*/
// }
}
long endTime = System.nanoTime();
long totalTime = (endTime - startTime)/1000;
System.out.print("Total Time: " + totalTime);
//} catch (FileNotFoundException e) {
//e.printStackTrace();
//}
}
}
I tried changing the path and using different built-in methods but nothing seems to work.
Try this:
public static void main(String[] args) throws IOException {
File directoryPath = new File("C:\\assignment 3\\links");
File[] files = directoryPath.listFiles();
for (File file : files) {
Scanner scan = new Scanner(file);
Notice the difference, using File.listFiles() instead of File.list().
public static void main(String[] args) throws IOException{
try {
List<String> line = Files.readAllLines(Paths.get("/home/madhu/Desktop/demo.txt"));
Scanner scanner = new Scanner((Readable) line);
List<FogDevice> fogdevices =new ArrayList<FogDevice>();
while(scanner.hasNextLine()){
String data[]=scanner.nextLine().split(" ");
System.out.println(data);
fogdevices.add(createFogDevice(data[0],Boolean.parseBoolean(data[1]),Long.parseLong(data[2]),Integer.parseInt(data[3]),Double.parseDouble(data[4]),Double.parseDouble(data[5]),Double.parseDouble(data[6])));
}
scanner.close();
System.out.println(fogdevices);
}catch (NumberFormatException e) {
System.out.println(e);
}
}
private static FogDevice createFogDevice(String name2, boolean x2,long mips2,int ram2, double ratepermips2,
double busypower2, double idlepower2) {
--------
---------some activity-----
return fogdevice ;
}
Format of demo.txt :
FD1,true,102400,4000,0.01,103,83.25
FD0,false,102400,4000,0.01,103,83.25
i want output in the below form by using createfogdevice function.
fogdevice1 : FD1,true,102400,4000,0.01,103,83.25
fogdevice2 : FD0,false,102400,4000,0.01,103,83.25
The problem is that you're confusing and mixing two different approaches to reading a file line-by-line. You started off using the nio method readAllLines, and then tried to switch gears to a Scanner and nextLine().
Either approach will work, you just have to pick one and stick with it.
So, if you like like readAllLines:
try {
List<String> line = Files.readAllLines(Paths.get("/home/madhu/Desktop/demo.txt"));
List<FogDevices> fogdevices = new ArrayList<>();
for (String l : line) {
String data[] = l.split("\\s*,\\s*");
System.out.println(data);
fogdevices.add(
createFogDevice(
data[0],
Boolean.parseBoolean(data[1]),
Long.parseLong(data[2]),
Integer.parseInt(data[3]),
Double.parseDouble(data[4]),
Double.parseDouble(data[5]),
Double.parseDouble(data[6])
));
}
System.out.println(fogdevices);
} catch (NumberFormatException e) {
System.out.println(e);
}
Or if you prefer to go with Scanner:
try {
Scanner scanner = new Scanner(Paths.get("/home/madhu/Desktop/demo.txt"));
List<FogDevices> fogdevices = new ArrayList<FogDevices>();
while (scanner.hasNextLine()) {
String data[] = scanner.nextLine().split("\\s*,\\s*");
System.out.println(data);
fogdevices.add(
createFogDevice(
data[0],
Boolean.parseBoolean(data[1]),
Long.parseLong(data[2]),
Integer.parseInt(data[3]),
Double.parseDouble(data[4]),
Double.parseDouble(data[5]),
Double.parseDouble(data[6])
));
}
scanner.close();
System.out.println(fogdevices);
} catch (NumberFormatException e) {
System.out.println(e);
}
I am have a project that need to modify some text in the text file.
Like BB,BO,BR,BZ,CL,VE-BR
I need make it become BB,BO,BZ,CL,VE.
and HU, LT, LV, UA, PT-PT/AR become HU, LT, LV, UA,/AR.
I have tried to type some code, however the code fail to loop and also,in this case.
IN/CI, GH, KE, NA, NG, SH, ZW /EE, HU, LT, LV, UA,/AR, BB
"AR, BB,BO,BR,BZ,CL, CO, CR, CW, DM, DO,VE-AR-BR-MX"
I want to delete the AR in second row, but it just delete the AR in first row.
I got no idea and seeking for helps.
Please
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.util.Scanner;
public class tomy {
static StringBuffer stringBufferOfData = new StringBuffer();
static StringBuffer stringBufferOfData1 = stringBufferOfData;
static String filename = null;
static String input = null;
static String s = "-";
static Scanner sc = new Scanner(s);
public static void main(String[] args) {
boolean fileRead = readFile();
if (fileRead) {
replacement();
writeToFile();
}
System.exit(0);
}
private static boolean readFile() {
System.out.println("Please enter your files name and path i.e C:\\test.txt: ");
filename = "C:\\test.txt";
Scanner fileToRead = null;
try {
fileToRead = new Scanner(new File(filename));
for (String line; fileToRead.hasNextLine()
&& (line = fileToRead.nextLine()) != null;) {
System.out.println(line);
stringBufferOfData.append(line).append("\r\n");
}
fileToRead.close();
return true;
} catch (FileNotFoundException ex) {
System.out.println("The file " + filename + " could not be found! "+ ex.getMessage());
return false;
} finally {
fileToRead.close();
return true;
}
}
private static void writeToFile() {
try {
BufferedWriter bufwriter = new BufferedWriter(new FileWriter(
filename));
bufwriter.write(stringBufferOfData.toString());
bufwriter.close();
} catch (Exception e) {// if an exception occurs
System.out.println("Error occured while attempting to write to file: "+ e.getMessage());
}
}
private static void replacement() {
System.out.println("Please enter the contents of a line you would like to edit: ");
String lineToEdit = sc.nextLine();
int startIndex = stringBufferOfData.indexOf(lineToEdit);
int endIndex = startIndex + lineToEdit.length() + 2;
String getdata = stringBufferOfData.substring(startIndex + 1, endIndex);
String data = " ";
Scanner sc1 = new Scanner(getdata);
Scanner sc2 = new Scanner(data);
String lineToEdit1 = sc1.nextLine();
String replacementText1 = sc2.nextLine();
int startIndex1 = stringBufferOfData.indexOf(lineToEdit1);
int endIndex1 = startIndex1 + lineToEdit1.length() + 3;
boolean test = lineToEdit.contains(getdata);
boolean testh = lineToEdit.contains("-");
System.out.println(startIndex);
if (testh = true) {
stringBufferOfData.replace(startIndex, endIndex, replacementText1);
stringBufferOfData.replace(startIndex1, endIndex1 - 2,
replacementText1);
System.out.println("Here is the new edited text:\n"
+ stringBufferOfData);
} else {
System.out.println("nth" + stringBufferOfData);
System.out.println(getdata);
}
}
}
I wrote a quick method for you that I think does what you want, i.e. remove all occurrences of a token in a line, where that token is embedded in the line and is identified by a leading dash.
The method reads the file and writes it straight out to a file after editing for the token. This would allow you to process a huge file without worrying about about memory constraints.
You can simply rename the output file after a successful edit. I'll leave it up to you to work that out.
If you feel you really must use string buffers to do in memory management, then grab the logic for the line editing from my method and modify it to work with string buffers.
static void onePassReadEditWrite(final String inputFilePath, final String outputPath)
{
// the input file
Scanner inputScanner = null;
// output file
FileWriter outputWriter = null;
try
{
// open the input file
inputScanner = new Scanner(new File(inputFilePath));
// open output file
File outputFile = new File(outputPath);
outputFile.createNewFile();
outputWriter = new FileWriter(outputFile);
try
{
for (
String lineToEdit = inputScanner.nextLine();
/*
* NOTE: when this loop attempts to read beyond EOF it will throw the
* java.util.NoSuchElementException exception which is caught in the
* containing try/catch block.
*
* As such there is NO predicate required for this loop.
*/;
lineToEdit = inputScanner.nextLine()
)
// scan all lines from input file
{
System.out.println("START LINE [" + lineToEdit + "]");
// get position of dash in line
int dashInLinePosition = lineToEdit.indexOf('-');
while (dashInLinePosition != -1)
// this line has needs editing
{
// split line on dash
String halfLeft = lineToEdit.substring(0, dashInLinePosition);
String halfRight = lineToEdit.substring(dashInLinePosition + 1);
// get token after dash that is to be removed from whole line
String tokenToRemove = halfRight.substring(0, 2);
// reconstruct line from the 2 halves without the dash
StringBuilder sb = new StringBuilder(halfLeft);
sb.append(halfRight.substring(0));
lineToEdit = sb.toString();
// get position of first token in line
int tokenInLinePosition = lineToEdit.indexOf(tokenToRemove);
while (tokenInLinePosition != -1)
// do for all tokens in line
{
// split line around token to be removed
String partLeft = lineToEdit.substring(0, tokenInLinePosition);
String partRight = lineToEdit.substring(tokenInLinePosition + tokenToRemove.length());
if ((!partRight.isEmpty()) && (partRight.charAt(0) == ','))
// remove prefix comma from right part
{
partRight = partRight.substring(1);
}
// reconstruct line from the left and right parts
sb.setLength(0);
sb = new StringBuilder(partLeft);
sb.append(partRight);
lineToEdit = sb.toString();
// find next token to be removed from line
tokenInLinePosition = lineToEdit.indexOf(tokenToRemove);
}
// handle additional dashes in line
dashInLinePosition = lineToEdit.indexOf('-');
}
System.out.println("FINAL LINE [" + lineToEdit + "]");
// write line to output file
outputWriter.write(lineToEdit);
outputWriter.write("\r\n");
}
}
catch (java.util.NoSuchElementException e)
// end of scan
{
}
finally
// housekeeping
{
outputWriter.close();
inputScanner.close();
}
}
catch(FileNotFoundException e)
{
e.printStackTrace();
}
catch(IOException e)
{
inputScanner.close();
e.printStackTrace();
}
}
My output is reflecting the file that I am needing to process into hex values but my hex values are not being reflected in the output. Why isn't my file being converted into hex values?
public class HexUtilityDump {
public static void main(String[] args) {
FileReader myFileReader = null;
try {
myFileReader = new FileReader("src/hexUtility/test.txt");
} catch(Exception ex) {
System.out.println("Error opening file: " + ex.getLocalizedMessage());
}
BufferedReader b = null;
b = new BufferedReader(myFileReader);
//Loop through all the records in the file and print them on the console
while (true){
String myLine;
try {
myLine = b.readLine();
//check for null returned from readLine() and exit loop if so.
if (myLine ==null){break;}
System.out.println(myLine);
} catch (IOException e) {
e.printStackTrace();
//it is time to exit the while loop
break;
}
}
}
Here is the code to pull the file through the conversion
public static void convertToHex(PrintStream out, File myFileReader) throws IOException {
InputStream is = new FileInputStream(myFileReader);
int bytesCounter =0;
int value = 0;
StringBuilder sbHex = new StringBuilder();
StringBuilder sbText = new StringBuilder();
StringBuilder sbResult = new StringBuilder();
while ((value = is.read()) != -1) {
//convert to hex value with "X" formatter
sbHex.append(String.format("%02X ", value));
//If the character is not convertible, just print a dot symbol "."
if (!Character.isISOControl(value)) {
sbText.append((char)value);
} else {
sbText.append(".");
}
//if 16 bytes are read, reset the counter,
//clear the StringBuilder for formatting purpose only.
if(bytesCounter==15) {
sbResult.append(sbHex).append(" ").append(sbText).append("\n");
sbHex.setLength(0);
sbText.setLength(0);
bytesCounter=0;
}else{
bytesCounter++;
}
}
//if still got content
if(bytesCounter!=0){
//add spaces more formatting purpose only
for(; bytesCounter<16; bytesCounter++){
//1 character 3 spaces
sbHex.append(" ");
}
sbResult.append(sbHex).append(" ").append(sbText).append("\n");
}
out.print(sbResult);
is.close();
}
You never call convertToHex, remove the file reading from your main() method. It appears you wanted to do something like,
File f = new File("src/hexUtility/test.txt");
convertToHex(System.out, f);
So I have been working on a java project where the goal is to create a virtual computer. So I am basically done but with one problem. I have created a compiler which translates a txt document with assembly code in it and my compiler has created a new-file with this code written as machine executable ints. But now I need to write a load method that reads these ints and runs the program but I am having difficulty doing this. Any help is much appreciated....also this is not homework if you are thinking this. The project was simply to make a compiler and now I am trying to complete it for my own interest. Thanks.
Here is what I have so far for load:
public void load(String newfile) throws FileNotFoundException
{
try{
File file = new File(newfile);
FileInputStream fs = new FileInputStream(file);
DataInputStream dos = new DataInputStream(fs);
dos.readInt();
dos.close();
}
catch (IOException e)
{
e.printStackTrace();
}
}
Ok here is the part of the Compiler that does the writeInts:
public void SecondPass(SymbolList symbolTable, String filename){
try {
int dc = 99;
//Open file for reading
File file = new File(filename);
Scanner scan = new Scanner(file);
//Make filename of new executable file
String newfile = makeFilename(filename);
//Open Output Stream for writing new file.
FileOutputStream fs = new FileOutputStream(newfile);
DataOutputStream dos = new DataOutputStream(fs);
//Read First line. Split line by Spaces into linearray.
String line = scan.nextLine();
String[] linearray = line.split(" ");
while(line!=null){
if(!linearray[0].equals("REM")){
int inst = 0, opcode, loc;
if(isInstruction(linearray[0])){
opcode = getOpcode(linearray[0]);
loc = symbolTable.searchName(linearray[1]).getMemloc();
inst = (opcode*100)+loc;
} else if(!isInstruction(linearray[0])){
if(isInstruction(linearray[1])){
opcode = getOpcode(linearray[1]);
if(linearray[1].equals("STOP"))
inst=0000;
else {
loc = symbolTable.searchName(linearray[2]).getMemloc();
inst = (opcode*100)+loc;
}
}
if(linearray[1].equals("DC"))
dc--;
}
dos.writeInt(inst);
System.out.println(" inst is being written as:" + inst);
}
try{
line = scan.nextLine();
}
catch(NoSuchElementException e){
line = null;
break;
}
linearray = line.split(" ");
}
scan.close();
for(int i=lc; i<=dc; i++){
dos.writeInt(0);
}
for(int i = dc+1; i < 100; i++)
{
dos.writeInt(symbolTable.searchLocation(i).getValue());
}
dos.close();
fs.close();
}
catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
So what I have done is write a file in txt like:
IN X
In Y
SUB X
STO Y
OUT Y
DC: X 0
DC: Y 0
And I wrote a compiler that has now converted this file into machine code so I have created a file for example called program.txt.ex and it contains a bunch of ####### or machine code and I did this using the SecondPass code above and now I need to write a load method that will allow me to load and run this file.
Here is my Run method
public void run(String filename) throws IOException
{
if (mem == null)
System.out.println("mem null");
if (filename == null)
System.out.println("filename null");
mem.loadFromFile(filename);
cpu.reset();
cpu.setMDR(mem.read(cpu.getMAR()));
cpu.fetch2();
while (!cpu.stop())
{
cpu.decode();
if (cpu.OutFlag())
OutPut.display(mem.read(cpu.getMAR()));
if (cpu.InFlag())
mem.write(cpu.getMDR(),in.getInt());
if (cpu.StoreFlag())
{
mem.write(cpu.getMAR(),in.getInt());
cpu.getMDR();
}
else
{
cpu.setMDR(mem.read(cpu.getMAR()));
cpu.execute();
cpu.fetch();
cpu.setMDR(mem.read(cpu.getMAR()));
cpu.fetch2();
}
}
}
The Run Method:
public void run(int mem)
{
cpu.reset();
cpu.setMDR(mem.read(cpu.getMAR()));
cpu.fetch2();
while (!cpu.stop())
{
cpu.decode();
if (cpu.OutFlag())
OutPut.display(mem.read(cpu.getMAR()));
if (cpu.InFlag())
mem.write(cpu.getMDR(),in.getInt());
if (cpu.StoreFlag())
{
mem.write(cpu.getMAR(),in.getInt());
cpu.getMDR();
}
else
{
cpu.setMDR(mem.read(cpu.getMAR()));
cpu.execute();
cpu.fetch();
cpu.setMDR(mem.read(cpu.getMAR()));
cpu.fetch2();
}
}
}
I notice that your loader does a single
dos.readInt();
...which will read a single integer value from your file. What you probably want to do is create a loop that reads ints until you hit the end-of-file on dos (which might more aptly be named dis, no?). You could add those ints to a dynamic container like an ArrayList, which will grow with every element you stuff into it. Once done loading, you can use toArray to copy all those ints to an array of the appropriate size.
If seems that you need to load the whole file in memory before starting execution, so it would go:
public int[] load(String newfile) throws FileNotFoundException
{
int mem[] = new int[100];
try {
File file = new File(newfile);
FileInputStream fs = new FileInputStream(file);
DataInputStream dis = new DataInputStream(fs);
for (int i = 0; i < mem.length; ++i) {
mem[i] = dis.readInt();
}
dos.readInt();
dos.close();
} catch (IOException e) {
e.printStackTrace();
}
return mem;
}
void run(int mem[]) {
// now execute code
int pc = 0;
loop: while (true) {
int inst = mem[pc++];
int opcode = inst/100;
int loc = inst%100;
switch (opcode) {
case OpCode.STOP:
break loop;
case OpCode.IN:
...
}
}
}