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Why am i getting nosuchelementexception in my code

Why am i getting NoSuchElementException?
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;
class GFG {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
int t = sc.nextInt();
sc.nextLine();
for (int k = 0; k < t; k++) {
int n = sc.nextInt();
int xn = sc.nextInt();
int yn = sc.nextInt();
sc.nextLine();
ArrayList<Integer> l1 = new ArrayList<Integer>(2000);
ArrayList<Integer> l2 = new ArrayList<Integer>(2000);
int a[] = new int[2000];
int b[] = new int[2000];
for (int i = 0; i < n; i++) {
a[i] = sc.nextInt();
l1.add(a[i]);
}
sc.nextLine();
for (int i = 0; i < n; i++) {
b[i] = sc.nextInt();
l2.add(b[i]);
}
int tip = 0;
while ((xn > 0) && (yn > 0)&& (!l2.isEmpty())&& (!l1.isEmpty())) {
int pi = l1.indexOf(Collections.max(l1));
if (l1.get(pi) >= l2.get(pi)) {
tip += l1.get(pi);
xn--;
} else {
tip += l2.get(pi);
yn--;
}
l2.remove(pi);
l1.remove(pi);
}
if (yn > 0) {
while ((yn > 0) && (!l2.isEmpty())) {
tip += Collections.max(l2);
l2.remove(l2.indexOf(Collections.max(l2)));
yn--;
}
} else {
while ((xn > 0) && (!l1.isEmpty())) {
tip += Collections.max(l1);
l1.remove(l1.indexOf(Collections.max(l1)));
xn--;
}
}
System.out.println(tip);
}
}
}
Output:
Runtime Error: Runtime ErrorException in thread "main"
java.util.NoSuchElementException at
java.util.Scanner.throwFor(Scanner.java:862) at
java.util.Scanner.next(Scanner.java:1485) at
java.util.Scanner.nextInt(Scanner.java:2117) at
java.util.Scanner.nextInt(Scanner.java:2076) at
GFG.main(File.java:22)

I added some logs here:
int tip = 0;
while ((xn > 0) && (yn > 0)) {
System.out.println("l1:"+l1);
System.out.println("Collections.max(l1):"+Collections.max(l1));
int pi = l1.indexOf(Collections.max(l1));
Entring 1 15 9 9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1
I get a different error.
It prints out:
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]
Collections.max(l1):15
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]
Collections.max(l1):14
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]
Collections.max(l1):13
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
Collections.max(l1):12
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11]
Collections.max(l1):11
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
Collections.max(l1):10
l1:[1, 2, 3, 4, 5, 6, 7, 8, 9]
Collections.max(l1):9
l1:[1, 2, 3, 4, 5, 6, 7, 8]
Collections.max(l1):8
l1:[1, 2, 3, 4, 5, 6, 7]
Collections.max(l1):7
l1:[1, 2, 3, 4, 5, 6]
Collections.max(l1):6
l1:[1, 2, 3, 4, 5]
Collections.max(l1):5
l1:[1, 2, 3, 4]
Collections.max(l1):4
l1:[1, 2, 3]
Collections.max(l1):3
l1:[1, 2]
Collections.max(l1):2
l1:[1]
Collections.max(l1):1
l1:[]
Exception in thread "main" java.util.NoSuchElementException
at java.util.ArrayList$Itr.next(ArrayList.java:854)
at java.util.Collections.max(Collections.java:669)
at GFG.main(GFG.java:31)
The problem is that you are calling Collections.max on en empty list.

Array of ArrayList with Integers filled with combinations

Suppose this, I obtain an array of Integer Wraps Objects...
Integer[] p = new Integer[]{7, 5, 3, 2}; //Variable Length
Now, I want create an Array of ArrayList with next respective values.
2
3
3, 2
5
5, 2
5, 3
5, 3, 2
7
7, 2
7, 3
7, 3, 2
7, 5
7, 5, 2
7, 5, 3, 2
7, 5, 3, 2
What code helps me to create an array with value shown before?
In this code I tried generate:
public static void generateTable(int index, int[] current, int[] values) {
if(index == values.length) {
for(int i = 0; i < values.length; i++) {
System.out.print((current[i]) + " ");
}
System.out.println();
} else {
current[index] = 0;
generateTable(index + 1, current, values);
current[index] = values[index];
generateTable(index + 1, current, values);
}
}
This code only show the combination I want to extract only the before combinations (Except Zero values).
0 0 0 0
0 0 0 2
0 0 3 0
0 0 3 2
0 5 0 0
0 5 0 2
0 5 3 0
0 5 3 2
7 0 0 0
7 0 0 2
7 0 3 0
7 0 3 2
7 5 0 0
7 5 0 2
7 5 3 0
7 5 3 2
I test with this code:
java.util.List<Integer>[] arr = new ArrayList[p.length];
for( int i = 0; i < p.length; i++) {
arr[i] = new ArrayList();
for (int j = 0; j <= i; j++) {
arr[i].add(p[j]);
}
System.out.println(arr[i]);
}
The output for before code is not working properly, is not recursive and doesn't show the omitted value like [5, 3, 2] or [7, 5, 2] , etc!
[7]
[7, 5]
[7, 5, 3]
[7, 5, 3, 2]

Instead of directly converting arrays into List. When you do that 0s will also be picked up and placed in your list. Iterate through each index of your array, find only non-zero elements and put them into your list. Can this help?

How to save a 2D array into a text file with BufferedWriter?

I'm trying to store a 2D array in a text file with BufferedWriter and I would also like to retrieve a 2D array from a text file and display in its original array format with BufferedReader. I have little experience with both methods.
The desired outcome to be saved in a txt file is:
1 5 7 8 2 3 9 6 4
4 8 3 7 6 9 2 1 5
6 2 9 5 1 4 7 3 8
5 3 1 9 4 2 6 8 7
2 7 4 3 8 6 5 9 1
8 9 6 1 7 5 3 4 2
9 4 8 2 3 7 1 5 6
3 6 2 4 5 1 8 7 9
7 1 5 6 9 8 4 2 3
BufferedWriter:
// Instantiate a Date object
static Date date = new Date();
static int[][] board = {{0, 0, 5, 9, 7, 1, 8, 4, 6},
{0, 7, 1, 2, 8, 6, 9, 3, 5},
{0, 9, 6, 4, 3, 5, 2, 7, 1},
{0, 6, 8, 7, 4, 9, 5, 2, 3},
{0, 4, 9, 5, 2, 3, 1, 6, 8},
{0, 5, 2, 1, 6, 8, 4, 9, 7},
{0, 2, 4, 8, 1, 7, 3, 5, 9},
{0, 1, 3, 6, 5, 2, 7, 8, 4},
{0, 8, 7, 3, 9, 4, 6, 1, 2}};
try {
File file = new File("/c:/sudoku" + date + ".txt");
if (!file.exists()) {
file.createNewFile();
}
FileWriter fw = new FileWriter(file.getAbsoluteFile());
try (BufferedWriter bw = new BufferedWriter(fw)) {
bw.write(board, 0, board.length());
}
System.out.println("Your Game was saved with success !");
} catch (IOException e) {
}

I suggest (as Bob did) to store it in csv format (comma separated values)
Date date = new Date();
int[][] board = {{0, 0, 5, 9, 7, 1, 8, 4, 6},
{0, 7, 1, 2, 8, 6, 9, 3, 5},
{0, 9, 6, 4, 3, 5, 2, 7, 1},
{0, 6, 8, 7, 4, 9, 5, 2, 3},
{0, 4, 9, 5, 2, 3, 1, 6, 8},
{0, 5, 2, 1, 6, 8, 4, 9, 7},
{0, 2, 4, 8, 1, 7, 3, 5, 9},
{0, 1, 3, 6, 5, 2, 7, 8, 4},
{0, 8, 7, 3, 9, 4, 6, 1, 2}};
StringBuilder builder = new StringBuilder();
for(int i = 0; i < board.length; i++)//for each row
{
for(int j = 0; j < board.length; j++)//for each column
{
builder.append(board[i][j]+"");//append to the output string
if(j < board.length - 1)//if this is not the last row element
builder.append(",");//then add comma (if you don't like commas you can use spaces)
}
builder.append("\n");//append new line at the end of the row
}
BufferedWriter writer = new BufferedWriter(new FileWriter("/c:/sudoku" + date + ".txt"));
writer.write(builder.toString());//save the string representation of the board
writer.close();
Hope it's all clear
EDIT:
Here is how to read back your board:
String savedGameFile = /*...*/;
int[][] board = new int[9][9];
BufferedReader reader = new BufferedReader(new FileReader(savedGameFile));
String line = "";
int row = 0;
while((line = reader.readLine()) != null)
{
String[] cols = line.split(","); //note that if you have used space as separator you have to split on " "
int col = 0;
for(String c : cols)
{
board[row][col] = Integer.parseInt(c);
col++;
}
row++;
}
reader.close();

Strange selection sort behavior

I have tried to attempt implementing my own Selection Sort code. So far, the code sorta works... It just behaves strangely.
class HelloWorld {
public static void main(String[] args) {
long startTime = System.currentTimeMillis();
int a[] = {
3,7,8,4,22,13,9,5,10
};
int max_pos = a.length-1;
int counter = 0;
int min_sort = 0;
int j = -1;
int min_pos = 0;
int i=0;
while (j < max_pos) {
i=j+1;
min_sort = a[i];
// traverse trough unsorted portion
while (i < max_pos) {
i++;
if (min_sort > a[i]) {
min_sort = a[i]; // minimum unsorted
min_pos = i;
}
}
// sorted portion
j++;
a[min_pos] = a[j];
a[j] = min_sort ;
for(int x=0; x < a.length; x++) {
System.out.print(a[x] + ", ");
}
System.out.print("\t\t");
System.out.println("i: " + i + " j: " + j + " min pos: " + min_pos + " min val: "+ min_sort);
}
}
}
I have tried tracing it, and the output goes like this:
3, 7, 8, 4, 22, 13, 9, 5, 10, i: 8 j: 0 min pos: 0 min val: 3
3, 4, 8, 7, 22, 13, 9, 5, 10, i: 8 j: 1 min pos: 3 min val: 4
3, 4, 5, 7, 22, 13, 9, 8, 10, i: 8 j: 2 min pos: 7 min val: 5
3, 4, 5, 7, 22, 13, 9, 7, 10, i: 8 j: 3 min pos: 7 min val: 7
3, 4, 5, 7, 7, 13, 9, 22, 10, i: 8 j: 4 min pos: 7 min val: 7
3, 4, 5, 7, 7, 9, 13, 22, 10, i: 8 j: 5 min pos: 6 min val: 9
3, 4, 5, 7, 7, 9, 10, 22, 13, i: 8 j: 6 min pos: 8 min val: 10
3, 4, 5, 7, 7, 9, 10, 13, 22, i: 8 j: 7 min pos: 8 min val: 13
3, 4, 5, 7, 7, 9, 10, 13, 22, i: 8 j: 8 min pos: 8 min val: 22

Since this is almost certainly an educational process on your part (real code would just call Arrays.sort()), I won't give a direct answer initially.
Instead, you should notice that it's the line where j == 3 which is when the 8 appears to magically transmogrify into a 7.
So you should start to hone your debugging skills. Run the code through a debugger up to the end of the output of the previous line, then single step every single instruction. At some point, you'll see the 7 become an 8 and that's the code you need to focus on.
Once you've done that, you'll hopefully be able to tell what the problem is. However, if you're still stuck (make sure you try first, or you'll never improve), see below.
t---
This is a detailed analysis of your problem. You are storing information about the minimum (both the value min_sort and its position min_pos) each time you find an element that's smaller than the first one you set up in each iteration of the outer loop:
if (min_sort > a[i]) {
min_sort = a[i]; // minimum unsorted
min_pos = i;
}
Now that's a good way to do it, and these two pieces of information are later used in the swapping process(1):
j++;
a[min_pos] = a[j];
a[j] = min_sort;
However, what of the case where you don't find an element smaller than the first one set up, such as the following where when position 3 holds the value 7 and all values beyond that are greater than 7:
3, 4, 5, 7, 22, 13, 9, 8, 10
^
In that case, the body of the if statement will never be run and the initial conditions from the start of the iteration will still apply:
i=j+1;
min_sort = a[i];
Notice anything missing there? Such as, let's see, the position being set to something?
Bingo! If the first element being checked in an iteration is already in its correct position, min_pos will remain set to whatever it was previously and, when you swap, that's not going to be pretty. You can fix that by changing the code immediately inside the outer while loop to be:
i = j + 1;
min_pos = i; // add this line
min_sort = a[i];
and you'll see the greatly improved (i.e., correct) output of:
3, 7, 8, 4, 22, 13, 9, 5, 10, i: 8 j: 0 min pos: 0 min val: 3
3, 4, 8, 7, 22, 13, 9, 5, 10, i: 8 j: 1 min pos: 3 min val: 4
3, 4, 5, 7, 22, 13, 9, 8, 10, i: 8 j: 2 min pos: 7 min val: 5
3, 4, 5, 7, 22, 13, 9, 8, 10, i: 8 j: 3 min pos: 3 min val: 7
3, 4, 5, 7, 8, 13, 9, 22, 10, i: 8 j: 4 min pos: 7 min val: 8
3, 4, 5, 7, 8, 9, 13, 22, 10, i: 8 j: 5 min pos: 6 min val: 9
3, 4, 5, 7, 8, 9, 10, 22, 13, i: 8 j: 6 min pos: 8 min val: 10
3, 4, 5, 7, 8, 9, 10, 13, 22, i: 8 j: 7 min pos: 8 min val: 13
3, 4, 5, 7, 8, 9, 10, 13, 22, i: 8 j: 8 min pos: 8 min val: 22
(1) The swap, by the way, is not necessary when the smallest remaining value is already in the correct position, though it does no harm. If you wanted to avoid the unnecessary swap, you could use:
j++;
if (min_pos != j) {
a[min_pos] = a[j];
a[j] = min_sort ;
}
However, as stated, it's not a problem to do the swap so it's really up to you.

Project Euler, problem 2- Java [closed]

Closed. This question is not reproducible or was caused by typos. It is not currently accepting answers.
This question was caused by a typo or a problem that can no longer be reproduced. While similar questions may be on-topic here, this one was resolved in a way less likely to help future readers.
Closed 8 years ago.
Improve this question
I'm a relatively new java programmer and I've been tinkering around with this program for the better part of the day now and I'm still stuck; I was hoping that you could help me with this.
So the program is supposed to meet the following requirements:
Each new term in the Fibonacci
sequence is generated by adding the
previous two terms. By starting with 1
and 2, the first 10 terms will be:
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, ...
By considering the terms in the
Fibonacci sequence whose values do not
exceed four million, find the sum of
the even-valued terms.
This is my code:
//Generates Fibonacci sequence
while (fibNum < 144)
{
int lastValue = (Integer) fibList.get(fibList.size()-1);
int secondToLastValue = (Integer) fibList.get(fibList.size()-2);
fibNum = secondToLastValue + lastValue;
if (fibNum < 144)
{
fibList.add(fibNum);
}
//Picks out the even numbers from limitFibList
for (int i = 0; i < fibList.size(); i++)
{
if ((Integer) fibList.get(i) % 2 == 0)
{
evenNumsFibList.add(fibList.get(i));
}
}
//Sums up the total value of the numbers in the evenNumsFibList
for (int i = 0; i < evenNumsFibList.size(); i++)
{
sum += (Integer) evenNumsFibList.get(i);
}
...and this is the output that I'm getting:
Fibonacci sequence list: [1, 2, 3]
Size of the Fibonacci list: 3
Even Numbers list: [2]
Total sum of even numbers: 2
Fibonacci sequence list: [1, 2, 3, 5]
Size of the Fibonacci list: 4
Even Numbers list: [2, 2]
Total sum of even numbers: 6
Fibonacci sequence list: [1, 2, 3, 5, 8]
Size of the Fibonacci list: 5
Even Numbers list: [2, 2, 2, 8]
Total sum of even numbers: 20
Fibonacci sequence list: [1, 2, 3, 5, 8, 13]
Size of the Fibonacci list: 6
Even Numbers list: [2, 2, 2, 8, 2, 8]
Total sum of even numbers: 44
Fibonacci sequence list: [1, 2, 3, 5, 8, 13, 21]
Size of the Fibonacci list: 7
Even Numbers list: [2, 2, 2, 8, 2, 8, 2, 8]
Total sum of even numbers: 78
Fibonacci sequence list: [1, 2, 3, 5, 8, 13, 21, 34]
Size of the Fibonacci list: 8
Even Numbers list: [2, 2, 2, 8, 2, 8, 2, 8, 2, 8, 34]
Total sum of even numbers: 156
Fibonacci sequence list: [1, 2, 3, 5, 8, 13, 21, 34, 55]
Size of the Fibonacci list: 9
Even Numbers list: [2, 2, 2, 8, 2, 8, 2, 8, 2, 8, 34, 2, 8, 34]
Total sum of even numbers: 278
Fibonacci sequence list: [1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
Size of the Fibonacci list: 10
Even Numbers list: [2, 2, 2, 8, 2, 8, 2, 8, 2, 8, 34, 2, 8, 34, 2, 8, 34]
Total sum of even numbers: 444
Fibonacci sequence list: [1, 2, 3, 5, 8, 13, 21, 34, 55, 89]
Size of the Fibonacci list: 10
Even Numbers list: [2, 2, 2, 8, 2, 8, 2, 8, 2, 8, 34, 2, 8, 34, 2, 8, 34, 2, 8, 34]
Total sum of even numbers: 654
Obviously my while loop is contributing to my problems, but I don't know how to fix it.
Would greatly appreciate your help,
Haque

If you take a closer look at the numbers in the Fibonacci sequence that you actually need (only the even ones need to be summed), you will see a pattern:
0 1 1 2 3 5 8 13 21 34 55 89 144 ...
- O O E O O E O O E O O E
Notice that every 3rd number starting after 0 is even. Therefore, you can eliminate any checking for evenness if you calculate every third Fibonacci number. Looking again at the sequence, you can see that if k is the present even Fibonacci number you are looking at, and j is the one previous, the next even Fibonacci number n can be obtained by:
n = 4k + j
So in Java, you could try something like this:
int j = 0;
int k = 2;
int sum = j+k;
while (k < LIMIT) {
int tmp = 4*k + j;
sum = sum + tmp;
j = k;
k = tmp;
}

Looks like you are missing the close brackets on the while loop. So the other for's are running within it.
So:
while (fibNum < 144)
{
int lastValue = (Integer) fibList.get(fibList.size()-1);
int secondToLastValue = (Integer) fibList.get(fibList.size()-2);
fibNum = secondToLastValue + lastValue;
if (fibNum < 144)
{
fibList.add(fibNum);
}
}
//Picks out the even numbers from limitFibList
for (int i = 0; i < fibList.size(); i++)
{...

Am I missing something? Why do you need to create list? You just need a sum of even-valued numbers? Right? If I understand you correctly you can get your sum in 10 lines of code... I don't have Java IDE opend, so I'll give you Pythone code. If it is what you need I'll convert it into Java.
def fib(n=4000001): # write Fibonacci series up to n
r = 0
a, b = 0, 1
while b < n:
if not b%2 :
print(b, end=' ')
r += b
a, b = b, a+b
return r
OUTPUT:
2 8 34 144 610 2584 10946 46368 196418 832040 3524578
sum = 4613732

public class Euler002 {
int counter = 0;
public int getCounter () {
return counter;
}
public int getFibTotal () {
final int UPPER_LIMIT = 4000000;
int fib1 = 0;
int fib2 = 1;
int newFib = fib1 + fib2;
int total = 0;
while (newFib < UPPER_LIMIT) {
counter++;
fib1 = fib2;
fib2 = newFib;
newFib = fib1 + fib2;
if ((newFib % 2) == 0) {
total += newFib;
}
}
return total;
}
/**
* #param args
*/
public static void main(String[] args) {
Euler002 euler002 = new Euler002();
int total = euler002.getFibTotal();
System.out.println(" Counter = " + euler002.getCounter() + " And Fib Total is " + total);
}
}

The problem is here:
for (int i = 0; i < fibList.size(); i++)
{
if ((Integer) fibList.get(i) % 2 == 0)
{
evenNumsFibList.add(fibList.get(i)); <-- HERE
}
}
You're adppending a whole new list of all the even numbers to the end of the list you already have.
You need to delete everything in evenNumsFibList before calling this loop again, or modify the loop to only add even numbers that are not already in the list.
That's assuming your indentation is incorrect. If your indentation is actually how you want it, then you're simply missing a closing bracket on your while loop.