Develop Reference

why isn't the rest of my method being called? (loop being ignored)

i'm trying to write a program that reads a file and then prints it out and then reads it again but only prints out the lines that begin with "The " the second time around. it DOES print out the contents of the file, but then it doesn't print out the lines that begin with "The " and i can't figure out why. it prints out the println line right before the loop, but then it ignores the for-loop completely. the only difference between my findThe method and my OutputTheArray method is the substring part, so i think that's the problem area but i don't know how to fix it.
import java.util.*;
import java.io.*;
public class EZD_readingFiles
{
public static int inputToArray(String fr[], Scanner sf)
{
int max = -1;
while(sf.hasNext())
{
max++;
fr[max] = sf.nextLine();
}
return max;
}
public static void findThe(String fr[], int max)
{
System.out.println("\nHere are the lines that begin with \"The\": \n");
for(int b = 0; b <= max; b++)
{
String s = fr[b].substring(0,4);
if(s.equals("The "))
{
System.out.println(fr[b]);
}
}
}
public static void OutputTheArray(String fr[], int max)
{
System.out.println("Here is the original file: \n");
for(int a = 0; a <= max; a++)
{
System.out.println(fr[a]);
}
}
public static void main(String args[]) throws IOException
{
Scanner sf = new Scanner(new File("EZD_readme.txt"));
String fr[] = new String[5];
int y = EZD_readingFiles.inputToArray(fr,sf);
EZD_readingFiles.OutputTheArray(fr,y);
int z = EZD_readingFiles.inputToArray(fr,sf);
EZD_readingFiles.findThe(fr,z);
sf.close();
}
}
this is my text file with the tester data (EZD_readme.txt):
Every man tries as hard as he can.
The best way is this way.
The schedule is very good.
Cosmo Kramer is a doofus.
The best movie was cancelled.

Try cloning sf and passing it to the other function.
Something like this:
Scanner sf = new Scanner(new File("EZD_readme.txt"));
Scanner sf1 = sf.clone();
int y = EZD_readingFiles.inputToArray(fr,sf);
EZD_readingFiles.OutputTheArray(fr,y);
int z = EZD_readingFiles.inputToArray(fr,sf1);
EZD_readingFiles.findThe(fr,z);
sf.close();
sf1.close();

How to convert big int number to Binary ? - Java

I am trying to convert int to binary and i am doing below code.
public static String intToBinary16Bit(String strInt) {
String bin = Integer.toBinaryString(strInt);
return String.format("%016d", Integer.parseInt(bin));
}
So, if i am giving strInt = 0211 than it is working fine and giving the output
0000001000010001.
But, if i am giving strInt = 4527 than it is throwing NumberFormateException.
How can I resolved this issue ?

Try what eznme suggests here:
public class A {
public static void main(String[] args) {
int a = Integer.parseInt(args[0]);
System.out.println(a);
int bit=1;
for(int i=0; i<32; i++) {
System.out.print(" "+(((a&bit)==0)?0:1));
bit*=2;
}
}
}

Try the following method, it uses recursion for conversion.
private static void toBinary(int number) {
int remainder;
if (number <= 1) {
System.out.print(number);
return;
}
remainder = number % 2;
toBinary(number >> 1);
System.out.println(remainder);
}

You try:
Long.toBinaryString(2199023255552L);
Java long to binary

Extras values after calling main method

This program works fine if i enter the correct value (int value). However, when I enter in a character or any other wrong value it displays the wrong input message and calls the main method again. The only problem is after calling the main method and inputting the correct input it prints out extra data why is that?
import javax.swing.JOptionPane;
public class TestPolyVal {
public static void main(String[] args){
int xValue = 0;
String value = JOptionPane.showInputDialog(null, "What is the value of X");
try{
xValue = Integer.parseInt(value);}
catch (NumberFormatException e){
JOptionPane.showMessageDialog(null,"Wrong input. Please input only integer values.");
TestPolyVal.main(args);
}
int[] intArray = new int[20] ;
for (int i = 0; i < 20; i ++){
intArray[i] = 2;}
System.out.println(calculateBruteForce(intArray,xValue));
System.out.println("0");
System.out.println(calculateHorner(intArray,xValue));}
static int calculateBruteForce(int[] a, int b){
int sum = 0 ;
for (int i = 0; i < 20; i ++){
sum +=a[i]*powerCalc(b,i);}
return sum;}
static int powerCalc(int c, int d){
int powerValue = c;
if (d==0){
powerValue = 1;}
else if (d==1){
powerValue = c;}
else if (d>1){
for (int i = 1; i<d;i++){
powerValue = powerValue*c;}}
return powerValue;}
static int calculateHorner(int[] e, int f){
int acc = e[e.length-1];
for(int i = e.length-2; i >= 0; i--){
acc = (acc * f)+ e[i];}
return acc;}
}

You are getting extra printouts because the first main execution will continue after the second main invocation is done.
This can be fixed by adding a return; after the new call to main:
catch (NumberFormatException e){
JOptionPane.showMessageDialog(null,"Wrong input. Please input only integer values.");
TestPolyVal.main(args);
return;
}

The approach of calling main() from within main() is not a great approach in this case. I, as an adversarial user, could just type 'a' in the dialog over and over again. Eventually this would cause a Stack Overflow Error and your program would crash.
I would suggest using a loop.
while(true) {
try{
xValue = Integer.parseInt(value);
break;
}
catch (NumberFormatException e){
JOptionPane.showMessageDialog(null,"Wrong input. Please input only integer values.");
}
}
This way your program would just loop forever or until the user enters correct input instead of crashing. Unless you're implementing a recursive algorithm, I can't think of any reason for a method to invoke itself.

Compiling Errors Java

When I try to compile this code, I keep coming up with compiling errors. The code is below.
import java.util.Scanner;
public class BaseballPitcher
{
private final int MAX_GAMES = 15;
private gamesPitched[];
private int totalGames;
private int totalRuns;
private float totalInnings;
private double ERA;
public BaseballPitcher()
{
gamesPitched = new GamePitched[];
}
public void inputGameData()
{
Scanner input = new Scanner (System.in);
do
{
System.out.printf ("How many games will you enter (up to %d): ", MAX_GAMES);
totalGames = input.nextInt();
if (totalGames <= 0 || totalGames > MAX_GAMES)
{
System.out.printf ("Error: You may only enter up to %d games" + " - Please try again\n\n", MAX_GAMES);
}
} while (totalGames <= 0 || totalGames > MAX_GAMES);
for (int x = 0, x < totalGames, x++)
{
gamesPitched[x] = new GamePitched();
gamesPitched[x].inputGame();
}
}
}
The compile errors I am receiving are:
[Please list your compile error or errors].
Why am I getting the compile errors?

It appears you have a custom class named GamePitched. Your array gamesPitched[] is likely supposed to be an array of this type, yet you have declared it without a type. Try private GamePitched[] gamesPitched;
Your loop just has syntax errors -- the , should be ;, which Java uses to separate the clauses in a for loop.
You should read the errors provided in the stacktrace. Even if you are new to Java, they are fairly descriptive and would help you identify where the problems exist (and often suggest the fix).

Well, this is how it should like, I guess
import java.util.Scanner;
public class BaseballPitcher
{
private final int MAX_GAMES = 15;
private GamePitched[] gamesPitched;
private int totalGames;
private int totalRuns;
private float totalInnings;
private double ERA;
public BaseballPitcher()
{
gamesPitched = new GamePitched[10];
}
public void inputGameData()
{
Scanner input = new Scanner (System.in);
do
{
System.out.printf ("How many games will you enter (up to %d): ", MAX_GAMES);
totalGames = input.nextInt();
if (totalGames <= 0 || totalGames > MAX_GAMES)
{
System.out.printf ("Error: You may only enter up to %d games" + " - Please try again\n\n", MAX_GAMES);
}
} while (totalGames <= 0 || totalGames > MAX_GAMES);
for (int x = 0; x < totalGames; x++)
{
gamesPitched[x] = new GamePitched();
gamesPitched[x].inputGame();
}
}
}
at least to compile. Cannot say anything about the logic
and the other class must have at least this method
public class GamePitched {
public void inputGame() {
// TODO Auto-generated method stub
}
}

Uva's 3n+1 problem

I'm solving Uva's 3n+1 problem and I don't get why the judge is rejecting my answer. The time limit hasn't been exceeded and the all test cases I've tried have run correctly so far.
import java.io.*;
public class NewClass{
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException {
int maxCounter= 0;
int input;
int lowerBound;
int upperBound;
int counter;
int numberOfCycles;
int maxCycles= 0;
int lowerInt;
BufferedReader consoleInput = new BufferedReader(new InputStreamReader(System.in));
String line = consoleInput.readLine();
String [] splitted = line.split(" ");
lowerBound = Integer.parseInt(splitted[0]);
upperBound = Integer.parseInt(splitted[1]);
int [] recentlyused = new int[1000001];
if (lowerBound > upperBound )
{
int h = upperBound;
upperBound = lowerBound;
lowerBound = h;
}
lowerInt = lowerBound;
while (lowerBound <= upperBound)
{
counter = lowerBound;
numberOfCycles = 0;
if (recentlyused[counter] == 0)
{
while ( counter != 1 )
{
if (recentlyused[counter] != 0)
{
numberOfCycles = recentlyused[counter] + numberOfCycles;
counter = 1;
}
else
{
if (counter % 2 == 0)
{
counter = counter /2;
}
else
{
counter = 3*counter + 1;
}
numberOfCycles++;
}
}
}
else
{
numberOfCycles = recentlyused[counter] + numberOfCycles;
counter = 1;
}
recentlyused[lowerBound] = numberOfCycles;
if (numberOfCycles > maxCycles)
{
maxCycles = numberOfCycles;
}
lowerBound++;
}
System.out.println(lowerInt +" "+ upperBound+ " "+ (maxCycles+1));
}
}

Are you making sure to accept the entire input? It looks like your program terminates after reading only one line, and then processing one line. You need to be able to accept the entire sample input at once.

I faced the same problem. The following changes worked for me:
Changed the class name to Main.
Removed the public modifier from the class name.
The following code gave a compilation error:
public class Optimal_Parking_11364 {
public static void main(String[] args) {
...
}
}
Whereas after the changes, the following code was accepted:
class Main {
public static void main(String[] args) {
...
}
}
This was a very very simple program. Hopefully, the same trick will also work for more complex programs.

If I understand correctly you are using a memoizing approach. You create a table where you store full results for all the elements you have already calculated so that you do not need to re-calculate results that you already know (calculated before).
The approach itself is not wrong, but there are a couple of things you must take into account. First, the input consists of a list of pairs, you are only processing the first pair. Then, you must take care of your memoizing table limits. You are assuming that all numbers you will hit fall in the range [1...1000001), but that is not true. For the input number 999999 (first odd number below the upper limit) the first operation will turn it into 3*n+1, which is way beyond the upper limit of the memoization table.
Some other things you may want to consider are halving the memoization table and only memorize odd numbers, since you can implement the divide by two operation almost free with bit operations (and checking for even-ness is also just one bit operation).

Did you make sure that the output was in the same order specified in the input. I see where you are swapping the input if the first input was higher than the second, but you also need to make sure that you don't alter the order it appears in the input when you print the results out.
ex.
Input
10 1
Output
10 1 20

If possible Please use this Java specification : to read input lines
http://online-judge.uva.es/problemset/data/p100.java.html
I think the most important thing in UVA judge is 1) Get the output Exactly same , No Extra Lines at the end or anywhere . 2) I am assuming , Never throw exception just return or break with No output for Outside boundary parameters.
3)Output is case sensitive 4)Output Parameters should Maintain Space as shown in problem
One possible solution based on above patterns is here
https://gist.github.com/4676999
/*
Problem URL: http://uva.onlinejudge.org/index.php?option=com_onlinejudge&Itemid=8&page=show_problem&problem=36
Home>Online Judge > submission Specifications
Sample code to read input is from : http://online-judge.uva.es/problemset/data/p100.java.html
Runtime : 1.068
*/
import java.io.*;
import java.util.*;
class Main
{
static String ReadLn (int maxLg) // utility function to read from stdin
{
byte lin[] = new byte [maxLg];
int lg = 0, car = -1;
String line = "";
try
{
while (lg < maxLg)
{
car = System.in.read();
if ((car < 0) || (car == '\n')) break;
lin [lg++] += car;
}
}
catch (IOException e)
{
return (null);
}
if ((car < 0) && (lg == 0)) return (null); // eof
return (new String (lin, 0, lg));
}
public static void main (String args[]) // entry point from OS
{
Main myWork = new Main(); // create a dinamic instance
myWork.Begin(); // the true entry point
}
void Begin()
{
String input;
StringTokenizer idata;
int a, b,max;
while ((input = Main.ReadLn (255)) != null)
{
idata = new StringTokenizer (input);
a = Integer.parseInt (idata.nextToken());
b = Integer.parseInt (idata.nextToken());
if (a<b){
max=work(a,b);
}else{
max=work(b,a);
}
System.out.println (a + " " + b + " " +max);
}
}
int work( int a , int b){
int max=0;
for ( int i=a;i<=b;i++){
int temp=process(i);
if (temp>max) max=temp;
}
return max;
}
int process (long n){
int count=1;
while(n!=1){
count++;
if (n%2==1){
n=n*3+1;
}else{
n=n>>1;
}
}
return count;
}
}

Please consider that the integers i and j must appear in the output in the same order in which they appeared in the input, so for:
10 1
You should print
10 1 20

package pandarium.java.preparing2topcoder;/*
* Main.java
* java program model for www.programming-challenges.com
*/
import java.io.*;
import java.util.*;
class Main implements Runnable{
static String ReadLn(int maxLg){ // utility function to read from stdin,
// Provided by Programming-challenges, edit for style only
byte lin[] = new byte [maxLg];
int lg = 0, car = -1;
String line = "";
try
{
while (lg < maxLg)
{
car = System.in.read();
if ((car < 0) || (car == '\n')) break;
lin [lg++] += car;
}
}
catch (IOException e)
{
return (null);
}
if ((car < 0) && (lg == 0)) return (null); // eof
return (new String (lin, 0, lg));
}
public static void main(String args[]) // entry point from OS
{
Main myWork = new Main(); // Construct the bootloader
myWork.run(); // execute
}
public void run() {
new myStuff().run();
}
}
class myStuff implements Runnable{
private String input;
private StringTokenizer idata;
private List<Integer> maxes;
public void run(){
String input;
StringTokenizer idata;
int a, b,max=Integer.MIN_VALUE;
while ((input = Main.ReadLn (255)) != null)
{
max=Integer.MIN_VALUE;
maxes=new ArrayList<Integer>();
idata = new StringTokenizer (input);
a = Integer.parseInt (idata.nextToken());
b = Integer.parseInt (idata.nextToken());
System.out.println(a + " " + b + " "+max);
}
}
private static int getCyclesCount(long counter){
int cyclesCount=0;
while (counter!=1)
{
if(counter%2==0)
counter=counter>>1;
else
counter=counter*3+1;
cyclesCount++;
}
cyclesCount++;
return cyclesCount;
}
// You can insert more classes here if you want.
}

This solution gets accepted within 0.5s. I had to remove the package modifier.
import java.util.*;
public class Main {
static Map<Integer, Integer> map = new HashMap<>();
private static int f(int N) {
if (N == 1) {
return 1;
}
if (map.containsKey(N)) {
return map.get(N);
}
if (N % 2 == 0) {
N >>= 1;
map.put(N, f(N));
return 1 + map.get(N);
} else {
N = 3*N + 1;
map.put(N, f(N) );
return 1 + map.get(N);
}
}
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
try {
while(scanner.hasNextLine()) {
int i = scanner.nextInt();
int j = scanner.nextInt();
int maxx = 0;
if (i <= j) {
for(int m = i; m <= j; m++) {
maxx = Math.max(Main.f(m), maxx);
}
} else {
for(int m = j; m <= i; m++) {
maxx = Math.max(Main.f(m), maxx);
}
}
System.out.println(i + " " + j + " " + maxx);
}
System.exit(0);
} catch (Exception e) {
}
}
}