I am new in java and I have to use the code below but the code it does work because I have to specifying the path for input data and output data. The code is got it from the internet. please help me
class Svm_scale
{
private BufferedReader rewind(BufferedReader fp, String filename) throws IOException
{
fp.close();
return new BufferedReader(new FileReader(filename));
}
private void output_target(double value)
{
LnCount++;
if(y_scaling)
{
if(value == y_min)
value = y_lower;
else if(value == y_max)
value = y_upper;
else
value = y_lower + (y_upper-y_lower) *
(value-y_min) / (y_max-y_min);
}
formatterscaled.format(value+" ");
System.out.println(" Line Number "+LnCount + " ");
}
private void output(int index, double value)
{
count++;
double Threshold1=0,Threshold2=0;
Threshold1= Avg[index]+(STDV[index]/2);
Threshold2= Avg[index]-(STDV[index]/2);
if(value > Threshold1 )
value = 2;
else if(value < Threshold2 )
value = -2;
else
value = 0;
formatterscaled.format( formatter.format(value) + ",");
// System.out.println(" Counter "+count);
// }
}
String save_filename =Save1; // = null?
String restore_filename =null;
String scale_data_filename =Disc; // set this to the path where the output should be stored, e.g. = "C:\\temp\\scaled";
String data_filename =Libsvm; // set this to the path where the input can be get, e.g. = "C:\\temp\\inputdata"
These are the Strings you need to adapt in order that the program can read and write. Save1, Disc, Libsvm are not in your code, so it can only be guessed where they come from.
data_filename and scale_data_filename are required. save_filename seems to be optional and may be set to null.
I am trying to write a program that converts binary(with or without fraction) inputs into hex which is nearly done but unfortunately in the hex output the point (".")is missing.
Suppose my expected output is e7.6 , but i am getting e76 instead.
only the "." is missing.
here is my BinToHex class..
import java.io.*;
//tried to convert the binary into dec and then dec to hex
public class BinToHex {
double tempDec,fractionpart;
long longofintpart,templongDec;
String inpu ="11100111.011";
String hexOutput=null,tempDecString,hex = null;
static int i = 1;
public void convertbintohex() {
if (inpu.contains(".")) {
int placesAfterPoint = inpu.length() - inpu.indexOf(".") - 1;//every thing
long numerator = Long.parseLong(inpu.replace(".", ""), 2);//goes
double decimalOfInput = ((double) numerator) / (1L << placesAfterPoint);//alright till here
while (true) {
tempDec = decimalOfInput * 16;
if (tempDec == (int)tempDec) {
tempDecString = String.valueOf((long)tempDec);
templongDec = Long.parseLong(tempDecString, 10);
hexOutput = Long.toHexString(templongDec);
break;
} else {
longofintpart = (long)tempDec;
hex=Long.toHexString(longofintpart);
if(i==1){
hexOutput = hex + ".";
i=i+1;
}else{
hexOutput = hexOutput + hex;
}
fractionpart = tempDec-(int)tempDec;
decimalOfInput = fractionpart;
}
}
} else {
// this part is ok
tempDecString = String.valueOf(Integer.parseInt(inpu, 2));
templongDec = Long.parseLong(tempDecString, 10);
hexOutput = Long.toHexString(templongDec);
}
System.out.println(hexOutput);
}
}
my main Test class..
public class Test{
public static void main(String args[]){
BinToHex i = new BinToHex();
i.convertbintohex();
}
}
I am stuck!
plz help .
really, not i can't resist to write a solution... after having such long comments, it jst takes me some minutes ^^
final int CODEBASE = 16;
String input = "11100111.011";
//lets see if we have a '.' in our String
if (input.indexOf(".") > 0) {
//yes, we have one - so we can split the string by '.'
String splits = input.split(".");
//the part left of the dot
String beforeDot = splits[0];
//the part right of the dot
String afterDot = splits[1];
//it's a incomplete input, we must fill up with
//trailing zeros according to out code base
afterDot.fillTrailingZeros(afterDot, CODEBASE);
//now we can parse the input
int asIntBefore = Integer.parseInt(beforeDots, 2);
int asIntAfter = Integer.parseInt(afterDot , 2);
} else {
//use your working code for
//input wthoput dot HERE
}
//fills trailing zeros to input String
String fillTrailingZeros(String input, int base){
//as long as our String is shorter than the codebase...
while (input.length() < base){
//...we have to add trailing zeros
input = input +"0";
}
return input;
}
At last found a proper algorithm for converting decimal(with or without fraction) to hex.
besides, binary(with or without fraction) to decimal in Java is here
The algorithm for converting decimal(with or without fraction) into hex in Java
import java.math.*;
public class DecimalToHex{
public String decimalToHex(String decInpString){
StringBuilder hexOut = new StringBuilder();
double doubleOfDecInp = Double.parseDouble(decInpString);
if(doubleOfDecInp < 0){
hexOut = hexOut.append("-");
doubleOfDecInp = -doubleOfDecInp;
}
BigInteger beforedot = new BigDecimal(doubleOfDecInp).toBigInteger();
hexOut.append(beforedot.toString(16));
BigDecimal bfd =new BigDecimal(beforedot);
doubleOfDecInp = doubleOfDecInp - bfd.doubleValue();
if(doubleOfDecInp == 0){
return hexOut.toString();
}
hexOut.append(".");
for (int i = 0; i < 16; ++i) {
doubleOfDecInp = doubleOfDecInp * 16;
int digit = (int)doubleOfDecInp;
hexOut.append(Integer.toHexString(digit));
doubleOfDecInp = doubleOfDecInp - digit;
if (doubleOfDecInp == 0)
break;
}
return hexOut.toString();
}
public static void main(String args[]){
String decimalInp = "-0.767";
String out ;
DecimalToHex i = new DecimalToHex();
out = i.decimalToHex(decimalInp);
System.out.println(out);
}
}
I have to write a program to convert between linear units in, ft, mi, mm, cm, m, km. I know there are easier and better ways to do this. I think we'ere just trying to fully understand if else if statements. But this is what I have so far. I'm just trying to figure out if I am on the right track. I've tried to write out some pseudocode but it just seems like a lot going on so I find it a bit overwhelming. Next I'm going to add a method to convert form in or mm to whatever is selected by the user.
When I test the program i get this: UnitConversion#76c5a2f7 (EDIT: THIS ISSUE WAS FIXED)
Ok I made the suggested changes and that allowed the first part of the program to run properly. I have now added my second method to convert from in/mm to the other measurements.. I was having issues but I figured it out.
Here is my main method;
public class LinearConversion
{
public static void main(String[] args)
{
UnitConversion newConvert = new UnitConversion("km", "m", 100);
System.out.println(newConvert);
}
}
Any suggestions? What am I missing or not understanding about doing this sort of program?
public class UnitConversion
{
private String input;
private String output;
private double value;
private double temp;
private double in, ft, mi, mm, cm, m, km;
private final double inch_feet = 12;
private final double inch_miles = 63360;
private final double inch_millimeters = 25.4;
private final double inch_centimeters = 2.54;
private final double inch_meters = 0.0254;
private final double inch_kilometers = 0.0000254;
private final double millimeters_inch = 0.0393701;
private final double millimeters_feet = 0.00328084;
private final double millimeters_miles = 0.000000622;
private final double millimeter_centimeters = 10;
private final double millimeter_meters = 1000;
private final double millimeter_kilometers = 1000000;
public UnitConversion(String in, String out, double val)
{
input = in;
output = out;
value = val;
}
public String toString()
{
if (input.equals("mi"))
{
in = value * inch_miles;
input = "in";
}
else if (input.equals("ft"))
{
in = value * inch_feet;
input = "in";
}
else
{
in = value;
input = "in";
}
if (input.equals("km"))
{
mm = value * millimeter_kilometers;
input = "mm";
}
else if (input.equals("m"))
{
mm = value * millimeter_meters;
input = "mm";
}
else if (input.equals("cm"))
{
mm = value * millimeter_centimeters;
input = "mm";
}
else
{
mm = value;
input = "mm";
}
return value + input + " " + output;
}
public double getUnit()
{
if (input.equals("in"))
{
if (output.equals("ft"))
{
ft = in * inch_feet;
System.out.println(ft + "ft");
}
else if (output.equals("mi"))
{
mi = in * inch_miles;
System.out.println(mi + "mi");
}
else if (output.equals("mm"))
{
mm = in * inch_millimeters;
System.out.println(mm + "mm");
}
else if (output.equals("cm"))
{
cm = in * inch_centimeters;
System.out.println(cm + "cm");
}
else if (output.equals("m"))
{
m = in * inch_meters;
System.out.println(m + "m");
}
else if (output.equals("km"))
{
km = in * inch_kilometers;
System.out.println(km + "km");
}
else
{
System.out.println(in + "in");
}
}
else
{
if (output.equals("cm"))
{
cm = mm * millimeter_centimeters;
System.out.println(cm + "cm");
}
else if (output.equals("m"))
{
m = mm * millimeter_meters;
System.out.println(m + "m");
}
else if (output.equals("km"))
{
km = mm * millimeter_kilometers;
System.out.println(km + "km");
}
else if (output.equals("in"))
{
in = mm * millimeters_inch;
System.out.println(in + "in");
}
else if (output.equals("ft"))
{
ft = mm * millimeters_feet;
System.out.println(ft + "ft");
}
else if (output.equals("mi"))
{
mi = mm * millimeters_miles;
System.out.println(mi + "mi");
}
else
{
System.out.println(mm + "mm");
}
}
}
Basically, you need/want to give a String argument to System.out.println in order to display it.
Thus, when you use System.out.println with an Object (that is not a String) as the argument, Java actually outputs the result of the toString method on that object.
If you haven't overridden it, the Object class' implementation of toString is used: this is what gives you your current output: UnitConversion#76c5a2f7.
To learn more about how is this default toString implementation generating that String, you can refer to the javadoc entry for Object#toString.
Base on your output, and your provided code, yes! Rename String getInput() to String toString() and your current main() will work, or change your current main()
System.out.println(newConvert.getInput()); // <-- added .getInput()
I am currently writing a program that will read through a designated text file that checks the transaction values of each buy/sell/summary and checks the arithmetic such that if the transactions from the buy and sell statements do not equal the total transaction amount that was given in the summary then it outputs an error and closes the program. But currently my method scanMoneyValue has an error that says it's not returning a double, when in fact it is. Is there a different way I should go about returning the values from my method? Here is my code for reference:
import java.io.File;
import java.io.IOException;
import java.util.Scanner;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
public class RecurrsionFileChecker {
public static void main(String[] args) {
int result;
//File Chooser Window
JFileChooser chooser = new JFileChooser("/home/nick/workspace/CS 1410-001/src/assignment03");
chooser.setDialogTitle("Please choose a file to be checked");
result = chooser.showOpenDialog(null);
//User Cancelled the chooser
if (result == JFileChooser.CANCEL_OPTION)
return;
File inputfile = chooser.getSelectedFile();
try
{
Scanner in = new Scanner(inputfile);
//Call Method to look at next transaction
scanNextTransaction(in);
}
catch (IOException e)
{
System.out.println("Could not read file: " + inputfile);
}
}
/**
* Returns double if the parameter Scanner has an error that does,
* not match the summary before it.
*
* #param s Any scanner
* #return double if Summaries don't match.
*/
public static double scanNextTransaction(Scanner s)
{
String buy, sell, summary, date;
double amount = 0, referenceValue, total = 0;
summary = s.next();
date = s.next();
referenceValue = scanMoneyValue(s);
while (s.hasNext())
{
if (s.next() == "Buy")
{
date = s.next();
amount = scanMoneyValue(s);
}
if(s.next() == "Sell")
{
date = s.next();
amount = scanMoneyValue(s);
}
if(s.next() == "Summary")
{
amount = scanSubSummary(s);
}
//add the transactions
total = total + amount;
}
return total;
}
public static double scanMoneyValue(Scanner in)
{
String dollar = in.next();
if(dollar.charAt(0) == '$')
{ //convert string to a double
String amount = dollar.substring(1);
double complete = Double.parseDouble(amount);
complete = complete * 100;
return complete;
}
}
public static double scanSubSummary(Scanner sub)
{
String summaryDate, transDate, transType;
int summarySubEntries, count = 0;
double transValue, summaryValue = 0, totalValue = 0, summaryAmount;
summaryDate = sub.next();
summaryAmount = scanMoneyValue(sub);
summarySubEntries = sub.nextInt();
while (count != summarySubEntries)
{
transType = sub.next();
if (transType == "Summary")
{
summaryValue = scanSubSummary(sub);
}
transValue = scanMoneyValue(sub);
totalValue = transValue + totalValue + summaryValue;
count++;
}
if (totalValue != summaryAmount)
{
System.out.print("Summary error on " + summaryDate + ".");
System.out.println("Amount is $" + summaryAmount + ", " + "should be $" + totalValue + ".");
}
return totalValue;
}
}
public static double scanMoneyValue(Scanner in)
{
String dollar = in.next();
if(dollar.charAt(0) == '$')
{ //convert string to a double
String amount = dollar.substring(1);
double complete = Double.parseDouble(amount);
complete = complete * 100;
return complete;
}
}
If the if condition fails then there's no return statement. You have a return inside of the condition but not outside. You'll need to add a return statement at the end, or throw an exception if not having a dollar sign is an error.
Okay, looking at the only relevant part of your code:
public static double scanMoneyValue(Scanner in)
{
String dollar = in.next();
if(dollar.charAt(0) == '$')
{ //convert string to a double
String amount = dollar.substring(1);
double complete = Double.parseDouble(amount);
complete = complete * 100;
return complete;
}
}
You do return a value if dollar starts with a $... but what do you expect to happen if it doesn't start with $? Currently you reach the end of the method without returning anything, which isn't valid.
You should probably throw an exception, if this is unexpected data that you can't actually handle.
Additionally, you shouldn't really use double for currency values anyway, due to the nature of binary floating point types. Consider using BigDecimal instead.
public static double scanMoneyValue(Scanner in)
{
String dollar = in.next();
if(dollar.charAt(0) == '$')
{ //convert string to a double
String amount = dollar.substring(1);
double complete = Double.parseDouble(amount);
complete = complete * 100;
return complete;
}
//NEED RETURN STATEMENT HERE
}
The error you get is because when you write a function all branches of that function must return a value of the correct type. In your case, if the if-statement fails it hits the end of the function without returning anything.
Its better to change it on
public static double scanMoneyValue(Scanner in)
{
String dollar = in.next();
String amount = dollar.replaceAll("[^\\d.]+", "")
double complete = Double.parseDouble(amount);
complete = complete * 100;
return complete;
}
link on explain - Parsing a currency String in java
I have a big text file (5Mb) that I use in my Android application. I create the file as a list of pre-sorted Strings, and the file doesn't change once it is created. How can I perform a binary search on the contents of this file, without reading line-by-line to find the matching String?
Since the content of the file does not change, you can break the file into multiple pieces. Say A-G, H-N, 0-T and U-Z. This allows you to check the first character and immediately be able to cut the possible set to a fourth of the original size. Now a linear search will not take as long or reading the whole file could be an option. This process could be extended if n/4 is still too large, but the idea is the same. Build the search breakdowns into the file structure instead of trying to do it all in memory.
A 5MB file isn't that big - you should be able to read each line into a String[] array, which you can then use java.util.Arrays.binarySearch() to find the line you want. This is my recommended approach.
If you don't want to read the whole file in to your app, then it gets more complicated. If each line of the file is the same length, and the file is already sorted, then you can open the file in RandomAccessFile and perform a binary search yourself by using seek() like this...
// open the file for reading
RandomAccessFile raf = new RandomAccessFile("myfile.txt","r");
String searchValue = "myline";
int lineSize = 50;
int numberOfLines = raf.length() / lineSize;
// perform the binary search...
byte[] lineBuffer = new byte[lineSize];
int bottom = 0;
int top = numberOfLines;
int middle;
while (bottom <= top){
middle = (bottom+top)/2;
raf.seek(middle*lineSize); // jump to this line in the file
raf.read(lineBuffer); // read the line from the file
String line = new String(lineBuffer); // convert the line to a String
int comparison = line.compareTo(searchValue);
if (comparison == 0){
// found it
break;
}
else if (comparison < 0){
// line comes before searchValue
bottom = middle + 1;
}
else {
// line comes after searchValue
top = middle - 1;
}
}
raf.close(); // close the file when you're finished
However, if the file doesn't have fixed-width lines, then you can't easily perform a binary search without loading it into memory first, as you can't quickly jump to a specific line in the file like you can with fixed-width lines.
Here's something I quickly put together. It uses two files, one with the words, the other with the offsets. The format of the offset file is this: the first 10 bits contains the word size, the last 22 bits contains the offset (the word position, for example, aaah would be 0, abasementable would be 4, etc.). It's encoded in big endian (java standard). Hope it helps somebody.
word.dat:
aaahabasementableabnormalabnormalityabortionistabortion-rightsabracadabra
wordx.dat:
00 80 00 00 01 20 00 04 00 80 00 0D 01 00 00 11 _____ __________
01 60 00 19 01 60 00 24 01 E0 00 2F 01 60 00 3E _`___`_$___/_`_>
I created these files in C#, but here's the code for it (it uses a txt file with words separated by crlfs)
static void Main(string[] args)
{
const string fIn = #"C:\projects\droid\WriteFiles\input\allwords.txt";
const string fwordxOut = #"C:\projects\droid\WriteFiles\output\wordx.dat";
const string fWordOut = #"C:\projects\droid\WriteFiles\output\word.dat";
int i = 0;
int offset = 0;
int j = 0;
var lines = File.ReadLines(fIn);
FileStream stream = new FileStream(fwordxOut, FileMode.Create, FileAccess.ReadWrite);
using (EndianBinaryWriter wwordxOut = new EndianBinaryWriter(EndianBitConverter.Big, stream))
{
using (StreamWriter wWordOut = new StreamWriter(File.Open(fWordOut, FileMode.Create)))
{
foreach (var line in lines)
{
wWordOut.Write(line);
i = offset | ((int)line.Length << 22); //first 10 bits to the left is the word size
offset = offset + (int)line.Length;
wwordxOut.Write(i);
//if (j == 7)
// break;
j++;
}
}
}
}
And this is the Java code for the binary file search:
public static void binarySearch() {
String TAG = "TEST";
String wordFilePath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/word.dat";
String wordxFilePath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/wordx.dat";
String target = "abracadabra";
boolean targetFound = false;
int searchCount = 0;
try {
RandomAccessFile raf = new RandomAccessFile(wordxFilePath, "r");
RandomAccessFile rafWord = new RandomAccessFile(wordFilePath, "r");
long low = 0;
long high = (raf.length() / 4) - 1;
int cur = 0;
long wordOffset = 0;
int len = 0;
while (high >= low) {
long mid = (low + high) / 2;
raf.seek(mid * 4);
cur = raf.readInt();
Log.v(TAG + "-cur", String.valueOf(cur));
len = cur >> 22; //word length
cur = cur & 0x3FFFFF; //first 10 bits are 0
rafWord.seek(cur);
byte [] bytes = new byte[len];
wordOffset = rafWord.read(bytes, 0, len);
Log.v(TAG + "-wordOffset", String.valueOf(wordOffset));
searchCount++;
String str = new String(bytes);
Log.v(TAG, str);
if (target.compareTo(str) < 0) {
high = mid - 1;
} else if (target.compareTo(str) == 0) {
targetFound = true;
break;
} else {
low = mid + 1;
}
}
raf.close();
rafWord.close();
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
if (targetFound == true) {
Log.v(TAG + "-found " , String.valueOf(searchCount));
} else {
Log.v(TAG + "-not found " , String.valueOf(searchCount));
}
}
In a uniform character length text file you could seek to the middle of the interval in question character wise, start reading characters until you hit your deliminator, then use the subsequent string as an approximation for the element wise middle. The problem with doing this in android, though, is you apparently can't get random access to a resource (although I suppose you could just reopen it every time). Furthermore this technique doesn't generalize to maps and sets of other types.
Another option would be to (using a RandomAccessFile) write an "array" of ints - one for each String - at the beginning of the file then go back and update them with the locations of their corresponding Strings. Again the search will require jumping around.
What I would do (and did do in my own app) is implement a hash set in a file. This one does separate chaining with trees.
import java.io.BufferedInputStream;
import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.RandomAccessFile;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedList;
import java.util.Set;
class StringFileSet {
private static final double loadFactor = 0.75;
public static void makeFile(String fileName, String comment, Set<String> set) throws IOException {
new File(fileName).delete();
RandomAccessFile fout = new RandomAccessFile(fileName, "rw");
//Write comment
fout.writeUTF(comment);
//Make bucket array
int numBuckets = (int)(set.size()/loadFactor);
ArrayList<ArrayList<String>> bucketArray = new ArrayList<ArrayList<String>>(numBuckets);
for (int ii = 0; ii < numBuckets; ii++){
bucketArray.add(new ArrayList<String>());
}
for (String key : set){
bucketArray.get(Math.abs(key.hashCode()%numBuckets)).add(key);
}
//Sort key lists in preparation for creating trees
for (ArrayList<String> keyList : bucketArray){
Collections.sort(keyList);
}
//Make queues in preparation for creating trees
class NodeInfo{
public final int lower;
public final int upper;
public final long callingOffset;
public NodeInfo(int lower, int upper, long callingOffset){
this.lower = lower;
this.upper = upper;
this.callingOffset = callingOffset;
}
}
ArrayList<LinkedList<NodeInfo>> queueList = new ArrayList<LinkedList<NodeInfo>>(numBuckets);
for (int ii = 0; ii < numBuckets; ii++){
queueList.add(new LinkedList<NodeInfo>());
}
//Write bucket array
fout.writeInt(numBuckets);
for (int index = 0; index < numBuckets; index++){
queueList.get(index).add(new NodeInfo(0, bucketArray.get(index).size()-1, fout.getFilePointer()));
fout.writeInt(-1);
}
//Write trees
for (int bucketIndex = 0; bucketIndex < numBuckets; bucketIndex++){
while (queueList.get(bucketIndex).size() != 0){
NodeInfo nodeInfo = queueList.get(bucketIndex).poll();
if (nodeInfo.lower <= nodeInfo.upper){
//Set respective pointer in parent node
fout.seek(nodeInfo.callingOffset);
fout.writeInt((int)(fout.length() - (nodeInfo.callingOffset + 4))); //Distance instead of absolute position so that the get method can use a DataInputStream
fout.seek(fout.length());
int middle = (nodeInfo.lower + nodeInfo.upper)/2;
//Key
fout.writeUTF(bucketArray.get(bucketIndex).get(middle));
//Left child
queueList.get(bucketIndex).add(new NodeInfo(nodeInfo.lower, middle-1, fout.getFilePointer()));
fout.writeInt(-1);
//Right child
queueList.get(bucketIndex).add(new NodeInfo(middle+1, nodeInfo.upper, fout.getFilePointer()));
fout.writeInt(-1);
}
}
}
fout.close();
}
private final String fileName;
private final int numBuckets;
private final int bucketArrayOffset;
public StringFileSet(String fileName) throws IOException {
this.fileName = fileName;
DataInputStream fin = new DataInputStream(new BufferedInputStream(new FileInputStream(fileName)));
short numBytes = fin.readShort();
fin.skipBytes(numBytes);
this.numBuckets = fin.readInt();
this.bucketArrayOffset = numBytes + 6;
fin.close();
}
public boolean contains(String key) throws IOException {
boolean containsKey = false;
DataInputStream fin = new DataInputStream(new BufferedInputStream(new FileInputStream(this.fileName)));
fin.skipBytes(4*(Math.abs(key.hashCode()%this.numBuckets)) + this.bucketArrayOffset);
int distance = fin.readInt();
while (distance != -1){
fin.skipBytes(distance);
String candidate = fin.readUTF();
if (key.compareTo(candidate) < 0){
distance = fin.readInt();
}else if (key.compareTo(candidate) > 0){
fin.skipBytes(4);
distance = fin.readInt();
}else{
fin.skipBytes(8);
containsKey = true;
break;
}
}
fin.close();
return containsKey;
}
}
A test program
import java.io.File;
import java.io.IOException;
import java.util.HashSet;
class Test {
public static void main(String[] args) throws IOException {
HashSet<String> stringMemorySet = new HashSet<String>();
stringMemorySet.add("red");
stringMemorySet.add("yellow");
stringMemorySet.add("blue");
StringFileSet.makeFile("stringSet", "Provided under ... included in all copies and derivatives ...", stringMemorySet);
StringFileSet stringFileSet = new StringFileSet("stringSet");
System.out.println("orange -> " + stringFileSet.contains("orange"));
System.out.println("red -> " + stringFileSet.contains("red"));
System.out.println("yellow -> " + stringFileSet.contains("yellow"));
System.out.println("blue -> " + stringFileSet.contains("blue"));
new File("stringSet").delete();
System.out.println();
}
}
You'll also need to pass a Context to it, if and when you modify it for android, so it can access the getResources() method.
You're also probably going to want to stop the android build tools from compressing the file, which can apparently only be done - if you're working with the GUI - by changing the file's extension to something such as jpg. This made the process about 100 to 300 times faster in my app.
You might also look into giving yourself more memory by using the NDK.
Though it might sound like overkill, don't store data you need to do this with as a flat file. Make a database and query the data in the database. This should be both effective and fast.
Here is a function that I think works (using this in practice). Lines can have any length. You have to supply a lambda called "nav" to do the actual line check so you are flexible in the file's order (case-sensitive, case-insensitive, ordered by a certain field etc.).
import java.io.File;
import java.io.RandomAccessFile;
class main {
// returns pair(character range in file, line) or null if not found
// if no exact match found, return line above
// nav takes a line and returns -1 (move up), 0 (found) or 1 (move down)
// The line supplied to nav is stripped of the trailing \n, but not the \r
// UTF-8 encoding is assumed
static Pair<LongRange, String> binarySearchForLineInTextFile(File file, IF1<String, Integer> nav) {
long length = l(file);
int bufSize = 1024;
RandomAccessFile raf = randomAccessFileForReading(file);
try {
long min = 0, max = length;
int direction = 0;
Pair<LongRange, String> possibleResult = null;
while (min < max) {
ping();
long middle = (min + max) / 2;
long lineStart = raf_findBeginningOfLine(raf, middle, bufSize);
long lineEnd = raf_findEndOfLine(raf, middle, bufSize);
String line = fromUtf8(raf_readFilePart(raf, lineStart, (int) (lineEnd - 1 - lineStart)));
direction = nav.get(line);
possibleResult = (Pair<LongRange, String>) new Pair(new LongRange(lineStart, lineEnd), line);
if (direction == 0) return possibleResult;
// asserts are to assure that loop terminates
if (direction < 0) max = assertLessThan(max, lineStart);
else min = assertBiggerThan(min, lineEnd);
}
if (direction >= 0) return possibleResult;
long lineStart = raf_findBeginningOfLine(raf, min - 1, bufSize);
String line = fromUtf8(raf_readFilePart(raf, lineStart, (int) (min - 1 - lineStart)));
return new Pair(new LongRange(lineStart, min), line);
} finally {
_close(raf);
}
}
static int l(byte[] a) {
return a == null ? 0 : a.length;
}
static long l(File f) {
return f == null ? 0 : f.length();
}
static RandomAccessFile randomAccessFileForReading(File path) {
try {
return new RandomAccessFile(path, "r");
} catch (Exception __e) {
throw rethrow(__e);
}
}
// you can change this function to allow interrupting long calculations from the outside. just throw a RuntimeException.
static boolean ping() {
return true;
}
static long raf_findBeginningOfLine(RandomAccessFile raf, long pos, int bufSize) {
try {
byte[] buf = new byte[bufSize];
while (pos > 0) {
long start = Math.max(pos - bufSize, 0);
raf.seek(start);
raf.readFully(buf, 0, (int) Math.min(pos - start, bufSize));
int idx = lastIndexOf_byteArray(buf, (byte) '\n');
if (idx >= 0) return start + idx + 1;
pos = start;
}
return 0;
} catch (Exception __e) {
throw rethrow(__e);
}
}
static long raf_findEndOfLine(RandomAccessFile raf, long pos, int bufSize) {
try {
byte[] buf = new byte[bufSize];
long length = raf.length();
while (pos < length) {
raf.seek(pos);
raf.readFully(buf, 0, (int) Math.min(length - pos, bufSize));
int idx = indexOf_byteArray(buf, (byte) '\n');
if (idx >= 0) return pos + idx + 1;
pos += bufSize;
}
return length;
} catch (Exception __e) {
throw rethrow(__e);
}
}
static String fromUtf8(byte[] bytes) {
try {
return bytes == null ? null : new String(bytes, "UTF-8");
} catch (Exception __e) {
throw rethrow(__e);
}
}
static byte[] raf_readFilePart(RandomAccessFile raf, long start, int l) {
try {
byte[] buf = new byte[l];
raf.seek(start);
raf.readFully(buf);
return buf;
} catch (Exception __e) {
throw rethrow(__e);
}
}
static <A> A assertLessThan(A a, A b) {
assertTrue(cmp(b, a) < 0);
return b;
}
static <A> A assertBiggerThan(A a, A b) {
assertTrue(cmp(b, a) > 0);
return b;
}
static void _close(AutoCloseable c) {
try {
if (c != null)
c.close();
} catch (Throwable e) {
throw rethrow(e);
}
}
static RuntimeException rethrow(Throwable t) {
throw t instanceof RuntimeException ? (RuntimeException) t : new RuntimeException(t);
}
static int lastIndexOf_byteArray(byte[] a, byte b) {
for (int i = l(a) - 1; i >= 0; i--)
if (a[i] == b)
return i;
return -1;
}
static int indexOf_byteArray(byte[] a, byte b) {
int n = l(a);
for (int i = 0; i < n; i++)
if (a[i] == b)
return i;
return -1;
}
static boolean assertTrue(boolean b) {
if (!b)
throw fail("oops");
return b;
}
static int cmp(Object a, Object b) {
if (a == null) return b == null ? 0 : -1;
if (b == null) return 1;
return ((Comparable) a).compareTo(b);
}
static RuntimeException fail(String msg) {
throw new RuntimeException(msg == null ? "" : msg);
}
final static class LongRange {
long start, end;
LongRange(long start, long end) {
this.end = end;
this.start = start;
}
public String toString() {
return "[" + start + ";" + end + "]";
}
}
interface IF1<A, B> {
B get(A a);
}
static class Pair<A, B> {
A a;
B b;
Pair(A a, B b) {
this.b = b;
this.a = a;
}
public String toString() {
return "<" + a + ", " + b + ">";
}
}
}