I am having some trouble with a Java program. I have a txt data file, which I will display, that I need to add into two separate arrays. The text file is 8 lines long that is supposed to go into two separate 4x4 matrices. A little background info on this program, reads in two arrays, compares them and outputs the largest elements of the same index and outputs them in a separate array. I somehow cannot seem to figure out how to add the data file into two separate arrays. My code is below, thanks in advance.
Data File:
2 7 6 4
6 1 2 4
9 7 2 6
8 3 2 1
4 1 3 7
6 2 3 8
7 2 2 4
4 2 3 1
Code:
public class prog465a
{
public static void main(String[] args) {
Scanner inFile = null;
try
{
inFile = new Scanner(new File("prog465a.dat.txt"));
}
catch(FileNotFoundException e)
{
System.out.println("File not found!");
System.exit(0);
}
int[][] firstData = new int[4][4];
int[][] secondData = new int[4][4];
int[][] finalData = new int[4][4];
for (int i = 0; i< 8; i++)
{
for(int j = 0; j < 8; j++)
{
if (i < 4 && j < 4){ //Trying to add first four lines to one matrix
firstData[i][j] = inFile.nextInt();
} else if (i >= 4 && j >= 4)
{
secondData[i][j] = inFile.nextInt();
}
}
}
for (int i = 0; i< 8; i++)
{
for(int j = 0; j < 8; j++)
{
if (firstData[i][j] >= secondData[i][j])
{
firstData[i][j] = finalData[i][j];
}
else if (secondData[i][j] >= firstData[i][j])
{
secondData[i][j] = finalData[i][j]
}
}
}
for ( int c = 0 ; c < finalData.length ; c++ )
{
for ( int d = 0 ; d < finalData.length ; d++ )
{
System.out.print(finalData[c][d]+" ");
}
System.out.print("\n");
}
}
}
The problems is that you are trying to parse a file with 8 rows and 8 column..
change this:
int[][] finalData = new int[4][4];
for (int i = 0; i< 8; i++)
{
for(int j = 0; j < 8; j++)
to:
int[][] finalData = new int[4][4];
for (int i = 0; i< 8; i++)
{
for(int j = 0; j < 4; j++)
that means 8 rows of file with 4 column each.
Also on the second part of your forloop again you are trying to get 8x8 matrix it should be 4x4..
change:
for (int i = 0; i< 8; i++)
{
for(int j = 0; j < 8; j++)
{
if (firstData[i][j] >= secondData[i][j])
{
firstData[i][j] = finalData[i][j];
}
else if (secondData[i][j] >= firstData[i][j])
{
secondData[i][j] = finalData[i][j]
}
}
}
to:
for (int i = 0; i< 4; i++)
{
for(int j = 0; j < 4; j++)
{
if (firstData[i][j] >= secondData[i][j] )
{
finalData[i][j] = firstData[i][j];
}
else if (secondData[i][j] >= firstData[i][j])
{
finalData[i][j] = secondData[i][j] ;
}
}
}
Related
I tried taking input of a 6 by 6 matrix in java using the string split function when the string is input in the following way, and to print the matrix.
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
1 2 3 4 5 6
The output that I get is
Main.java:24: error: incompatible types: String[] cannot be converted to String
c[j] = b[i].split(" ");
my code:
import java.util.*;
import java.io.*;
class Solution {
public static void main(String args[]) {
Scanner s = new Scanner(System.in);
int a[][] = new int[6][6];
String b[] = new String[6];
for (int i = 0; i < 6; i++) {
b[i] = s.nextLine();
}
// initializing the 2d array a[][]
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
String c[] = new String[6];
c[j] = b[i].split(" ");
a[i][j] = Integer.parseInt(c[j]);
}
}
// printing the input array
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
System.out.print("\ta[i][j]\t");
}
}
}
}
pls, suggest how I can overcome this error
When we call split function of String return the String[]. So c[j] (which is of type String) can't be equal to String[].
Below code should be replaced as:
// initializing the 2d array a[][]
for (int i = 0; i < 6; i++) {
String[] c = b[i].split(" ");
for (int j = 0; j < 6; j++) {
a[i][j] = Integer.parseInt(c[j]);
}
}
The return type of split() function is type of array. Because you are asking java to give me each value as separate which is separated by " " (space). So java will create an array of each value and returns you the array. For storing the array you need an variable of type array. here c represent an array, but c[j] represents an single index of the array.
You can change your code like:
for (int i = 0; i < 6; i++) {
String c[] = b[i].split(" ");
for (int k = 0; k < c.length; k++) {
a[i][k] = Integer.parseInt(c[k]);
}
}
The the inputs are integer and you are converting them to integer later, I would suggest you to take input as integer like below:
class Solution {
public static void main(String args[]) {
Scanner s = new Scanner(System.in);
int a[][] = new int[6][6];
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
a[i][j] = s.nextInt();
}
}
// printing the input array
for (int i = 0; i < 6; i++) {
for (int j = 0; j < 6; j++) {
System.out.print("\ta[i][j]\t");
}
}
}
}
So I'm currently playing around with multidimensional arrays (2D) and I'm trying to reverse the order of each array in a 2-d array.
So I have a 2D-array set as:
int firstArray[][] = {{5,6,7,8,9,10}, {11,12,13,14,15,16}}
I have manually looked through the issue to see where I may have went wrong, to see which part of my code would end up going out of bounds in regards to my for-loops. The -1 part also caught me off guard.
I have began doing reverses on a regular 1-d array, and tried to apply the same concept to multidimensional arrays.
class Test2 {
public static void main (String[] args) {
int firstArray[][] = {{5,6,7,8,9,10}, {10,11, 12, 13, 14, 15}};
System.out.println("FIRST ARRAY");
display(firstArray);
}
public void display(int [][]num) {
for (int i = 0; i < num.length; i++) {
for (int j = 0; j < num[i].length/2; j++) {
int temp = num[i][j];
num[i][j] = num[i][num.length-1-j];
num[i][num.length-1-j] = temp;
}
}
for (int a = 0; a < num.length; a++) {
for (int b = 0; b < num[a].length; b++) {
System.out.print(num[a][b] + "\t");
}
System.out.println();
}
}
}
I want the output using my display method to basically be a reverse of the arrays in my 2-d array:
10 9 8 7 6 5
15 14 13 12 11 10
The issue that I'm getting is an
Exception in thread "main"java.lang.ArrayIndexOutOfBoundsException: -1
ArrayIndexOutOfBoundsException: -1
at Test2.display(Test2.java:30)
at Test2.main(Test2.java:20)
You are using the length of the wrong dimension.
With num.length you are using the number of rows and not the number of columns of the current row.
You need to change that to num[i].length.
public static void display(int [][]num) {
for (int i = 0; i < num.length; i++) {
for (int j = 0; j < num[i].length/2; j++) {
int temp = num[i][j];
num[i][j] = num[i][num[i].length-1-j];
num[i][num[i].length-1-j] = temp;
}
}
for (int a = 0; a < num.length; a++) {
for (int b = 0; b < num[a].length; b++) {
System.out.print(num[a][b] + "\t");
}
System.out.println();
}
}
Notice you wrote num[i][num.length-1-j];
num.length-1-j is basically 2 - 1 -j.
public static void display(int [][]num) {
for (int i = 0; i < num.length; i++) {
for (int j = 0; j < num[i].length/2 ; j++) {
int temp = num[i][j];
num[i][j] = num[i][num[i].length-1-j];
num[i][num[i].length-1-j] = temp;
}
}
for (int a = 0; a < num.length; a++) {
for (int b = 0; b < num[a].length; b++) {
System.out.print(num[a][b] + "\t");
}
System.out.println();
}
}
This question already has answers here:
Syntax for creating a two-dimensional array in Java
(13 answers)
Closed 3 years ago.
I am working with 2-D arrays and I require help on this topic. My task is to create a 2-D array such that it is n by n (i.e. the number of rows and columns are equal). Fill the array with alternating 0's and 1's
void setup()
{
int n=3;
// code to populate the array
// code to display the output of array in a table format
/* output should be as follows:
The expected result when n=3 should be as the following:
1 0 1
0 1 0
1 0 1
*/
}
Solution:
class test{
public static void main(String[] args) {
int n = 3;
int[][] arr = setup(n);
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.print(arr[i][j]);
}
System.out.println();
}
}
static int[][] setup(int n){
int[][] arr = new int [n][n];
boolean even = false;
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
arr[i][j] = even ? 1 : 0;
even = !even;
}
}
return arr;
}
}
Output:
0 1 0
1 0 1
0 1 0
This should work.
You can replace the 3 that is given to n with any number you want as the 2D-Array's length.
void setup(){
int n = 3;
int count = 0;
int[][] myArray = new int[n][n];
for(int i = 0; i < n; i++){
for(int j = 0; j < n; j++){
if(count % 2 == 0){
myArray[i][j] = 1;
}
else{
myArray[i][j] = 0;
}
System.out.print(myArray[i][j] + " ");
count++;
}
System.out.println();
}
}
Output:
0 1 0
1 0 1
0 1 0
It's not complex, you just have to iterate two loops, that's it. Although you can get the solution on different ways.
public static void main(String[] args) {
int n = 3;
int [][] arr = new int[n][n];
int val = 1;
for(int i=0; i<n; i++) {
for(int j=0; j<n; j++) {
arr[i][j] = val;
val = (val == 0) ? 1 : 0;
}
}
for(int i=0; i<n; i++) {
for(int j=0; j<n; j++) {
System.out.print(arr[i][j] + " ");
}
System.out.println();
}
}
Output:
0 1 0
1 0 1
0 1 0
A simple implementation:
void setup()
{
int n=3;
final int[][] array = new int[n][n];
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if ((n * i + j) % 2 == 0) {
array[i][j] = 1;
}
}
}
}
Here is how you can approach your logic , create a counter and negate each time after it prints value.
public static void main(String[] args) {
int counter = 0;
int n = 3;
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= n; j++) {
System.out.print(counter==0?1:0);
counter = ~counter;
}
System.out.println();
}
}
Output
101
010
101
Here is Online source code.
I am trying to write a nested for loop that will print out the values of the following code in a specific order:
public static void main(String[] args) {
int[][] array2d = new int[3][5];
for (int i = 0; i < array2d.length; i++) {
for (int j = 0; j < array2d[0].length; j++) {
array2d[i][j] = (i * array2d[0].length) + j + 1;
}
}
for (int x = 0; x <= 4; x++) {
for (int y = 0; y <= 2; y++) {
System.out.println(array2d[y][x]);
}
}
}
}
The current array prints the way I want it, but each printout on a separate line.
I want the output (on a single line) to be this:
1 6 11 2 7 12 3 8 13 4 9 14 5 10 15
Thanks for the help.
You can use System.out.print instead:
System.out.print(array2d[y][x] + " ");
Replace println with print and it should work
String s = "";
for (int i = 0; i < array2d.length; i++) {
for (int j = 0; j < array2d[i].length; j++) {
s += array2d[i][j] + " ";
}
}
System.out.println(s);
public static void main(String[] args) {
int[][] array2d = new int[3][5];
for (int i = 0; i < array2d.length; i++) {
for (int j = 0; j < array2d[0].length; j++) {
array2d[i][j] = (i * array2d[0].length) + j + 1;
}
}
StringBuilder builder = new StringBuilder();
for (int x = 0; x <= 4; x++) {
for (int y = 0; y <= 2; y++) {
builder.append(array2d[y][x]);
if(!(x == 4 && y == 2)){
builder.append(" ");
}
}
}
System.out.println(builder.toString());
}
You basically had it right, except for changing the println to be print and formatting the string how you want. I changed it a little to show how the StringBuilder works. Whenever possible I use a StringBuilder because it is more convenient.
My professor wants me to print out the matrices side by side with the "+" between the two matrices and then a "=" sign. In the end he wants us to add the matrices together.
This is the work so far.
So the result would come out as:
1 2 3 9 8 7 10 10 10
4 5 6 + 6 5 4 = 10 10 10
7 8 9 3 2 1 10 10 10
enter code here public static void main(String[] args) {
int matrix1[][] = {{1,2,3},{4,5,6},{6,7,8}};
int matrix2[][] = {{9,8,7},{6,5,4},{3,2,1}};
int result1;
int[][] result2 = new int[2][3];
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[0].length; j++) {
System.out.printf(matrix1[i][j] + " ");
System.out.print("");
}
System.out.println("");
}
for (int i = 0; i < matrix2.length; i++) {
for (int j = 0; j < matrix2[0].length; j++) {
System.out.printf(matrix2[i][j] + " ");
}
System.out.println("");
}
}
My problem is, how could I print it side by side with the solutions?
Consider the two printing loops for your matrices:
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[0].length; j++) {
System.out.printf(matrix1[i][j] + " ");
}
System.out.println("");
}
for (int i = 0; i < matrix2.length; i++) {
for (int j = 0; j < matrix2[0].length; j++) {
System.out.printf(matrix2[i][j] + " ");
}
System.out.println("");
}
They print matrix 1, then 2 - and so the matrices will be below each other.
If you want the matrices side by side, you need to print line 1 of every matrix, then - after a new line - line 2 of every matrix, etc. By re-arranging how the loops go through the matrices, you could have your new layout.
You unfortunately cannot print them one at a time, you need to take it row by row. This solution requires both matrix1 and matrix2 to be of equal height. But here's a template that should get you started.
for (int i = 0; i < matrix1.length; i++) {
for (int j = 0; j < matrix1[i].length; j++) {
}
if (i == matrix1/2) {
} else { //One part of if handles when "+" is needed, other one doesn't
}
for (int j = 0; j < matrix2[i].length; j++) {
}
if (i == matrix1/2) {
}
for (int j = 0; j < ???; j++) {
}
}