I need little help on a homework assignment. I have to create a 10 by 10 ArrayList, not an array. This is what I have and I just need a hint on how to do a for loop to add the date to the 2D ArrayList. By the way this is for putting data that are grades; going from 100 to 82. (Yes I know it is homework but need to be pointed in the correct direction)
public void q6()
{
//part a
ArrayList<ArrayList<Double>> grades;
//part b
grades = new ArrayList<ArrayList<Double>>(10);
//second dimension
grades.add(new ArrayList<Double>(10));
for(int i = 0; i < 10; i++)
{
for(int j = 0; j < 10; j++)
{
// grades.get().add(); Not sure what to do here?
// If this was an array I would do something like:
// grades[i][j] = 100 -j -i;
}
}
}
Something like this could do?
public void q6()
{
//part a
ArrayList<ArrayList<Double>> grades;
//part b
grades = new ArrayList<ArrayList<Double>>(10);
//second dimension
for(int i = 0; i < 10; i++)
{
List<Double> current = new ArrayList<Double>(10);
grades.add(current);
for(int j = 0; j < 10; j++)
{
current.add(100 - j - i);
}
}
}
Given the code, all you left to do is change it a little to receive 10x10 matrix.
public class Main
{
public static final int ROW_COUNT = 5;
public static final int COL_COUNT = 10;
public static void main(String[] args)
{
ArrayList<ArrayList<Double>> grades = new ArrayList<ArrayList<Double>>();
for (int i = 0; i < ROW_COUNT; i++)
{
ArrayList<Double> row = new ArrayList<Double>();
for (int j = 0; j < COL_COUNT; j++)
{
row.add(100.0 - j - i);
}
grades.add(row);
}
for (int i = 0; i < ROW_COUNT; i++)
{
for (int j = 0; j < COL_COUNT; j++)
{
System.out.print(grades.get(i).get(j));
System.out.print(", ");
}
System.out.println("");
}
}
}
Related
In this exercise we have to draw a rectangle using two-dimensional arrays that goes from 10 to 15 rows and 20 to 30 column, putting in the border of the rectangle "#" while putting inside the rectangle "-". It has to look something like this: https://i.stack.imgur.com/IOqY6.png
The code I have so far is this, but I need some help fixing it since I'm a bit lost with the exercise:
public class Practica9{
public static void main(String[] args){
char [][] tablero = new char [10][20];
for (int i = 0; i < 10; i++){
for (int j = 0; j < 20; j++){
tablero [0][19] = #;
tablero [9][19] = #;
System.out.println (tablero[0][19]);
System.out.println (tablero[9][19]);
}
}
for (int i = 0; i < 10; i++){
for (int j = 0; j < 20; j++){
tablero [1][18] = -;
tablero [8][18] = -;
System.out.println (tablero [1][18]);
System.out.println (tablero [8][18]);
}
}
}
}
public static void main(String[] args){
int rows = 15;
int columns =30;
char [][] rectangle = new char[rows][columns];
// fill array
for(int i = 0; i < rows; i++){
for(int j = 0; j < columns; j++){
if(i==0 || j==0 || i==rows-1 || j==columns-1){
rectangle[i][j] = '#';
}
else{
rectangle[i][j] = '-';
}
}
}
// print array
for(int i = 0; i < rows; i++){
for(int j = 0; j < columns; j++){
System.out.print(rectangle[i][j]);
}
System.out.println();
}
}
It only prints out the average to the first column but doesn't do anything for the next.
it only prints out 717, for the first column average. It is a ragged array. Everything else compiles fine.
import java.util.Scanner;
import java.io.*;
public class Fitness
{
public static void main(String [] args)
{
int [][] week = {{800,1000,100},{450,100,845,20,1200,200},{1800,250,400},{0,1500,800,120},{600,500},{700,1400,1700,100},{675}};
System.out.println("Average over 7 days");
avgCalb(week);
static void avgCalb(int [][] x)
{
for(int j = 0; j < x[0].length; j++)
{
int colTotal = 0;
for(int i = 0; i < x.length; i++)
{
colTotal = colTotal + x[i][j];
}
System.out.println(colTotal/7);
break;
}
}
}
summing columns
static void avgCalb(int [][] x)
{
int[] colTotal = new int[x.length];
for(int j = 0; j < x.length; j++)
{
for(int i = 0; i < x[j].length; i++)
{
colTotal[i] += x[j][i]
}
}
for(int i = 0;i<colTotal.length;i++) {
System.out.println((double)colTotal[i]/colTotal.length);
}
}
summing rows
static void avgCalb(int [][] x)
{
for(int j = 0; j < x.length; j++)
{
int colTotal = 0;
for(int i = 0; i < x[j].length; i++)
{
colTotal += x[j][i];
}
System.out.println(colTotal/x[j].length);
}
}
How can I make a program that prompts the size of an array and fill it with random numbers, and then add all the numbers that are not at the edge?
Heres the code:
import javax.swing.*;
public class array {
int matrizNN[][];
public void setMatrizNN(int n){
matrizNN = new int[n][n];
for (int i = 0; i < matrizNN.length; i++) {
for (int j = 0; j < matrizNN[i].length; j++) {
matrizNN[i][j]= (int)(Math.random()*10);
System.out.print(" "+matrizNN[i][j]);
}
System.out.println(" ");
}
}
import javax.swing.*;
public class array {
int matrizNN[][];
public void setMatrizNN(int n){
matrizNN = new int[n][n];
for (int i = 0; i < matrizNN.length; i++) {
for (int j = 0; j < matrizNN[i].length; j++) {
matrizNN[i][j]= (int)(Math.random()*10);
System.out.print(" "+matrizNN[i][j]);
}
System.out.println(" ");
System.out.println("Size "+matrizNN.Length);
}
}
public static void setMatrizNN(int n){
matrizNN = new int[n][n];
for (int i = 0; i < matrizNN.length; i++) {
for (int j = 0; j < matrizNN[i].length; j++) {
matrizNN[i][j]= (int)(Math.random()*10);
System.out.print(" "+matrizNN[i][j]);
}
System.out.println(" ");
}
int sum=0;
System.out.println("=========================");
for (int i = 1; i < matrizNN.length-1; i++) {
for (int j = 1; j < matrizNN[i].length-1; j++) {
//System.out.print(matrizNN[i][j]);
sum+=matrizNN[i][j];
}
}
System.out.println("sum is :"+sum);
}
If you havent find the solution yet here is the code. Hope this is what you want.
You seem to have an idea of how to fill matrizNN[][]. To add the non-edge values up, you can use a similar set of for loops but with the first and last values omitted. Here's the basic idea:
int centerTotal = 0;
for (int i = 1; i < matrizNN.length - 1; i++) {
for (int j = 1; j < matrizNN[i].length - 1; j++) {
centerTotal += matrizNN[i][j];
}
}
System.out.println(centerTotal);
How do I fix this error and what does it mean?
java.lang.ArrayIndexOutOfBoundsException: 5
at Sort.sort(Sort.java:29)
at Sort.<init>(Sort.java:13)
at SortedArray.<init>(SortedArray.java:23)
Here is the code:
import java.util.Scanner;
import java.util.Random;
public class SortedArray
{
Scanner input = new Scanner(System.in);
int [] Array;
Sort sortedArray;
int sizeOfArray;
public SortedArray()
{
System.out.print("Enter the number of values to put in the array: ");
sizeOfArray = input.nextInt();
Array = new int [sizeOfArray];
System.out.println("");
for(int i = 0; i < sizeOfArray; i++)
{
Random r = new Random();
Array[i] = r.nextInt(100) + 1;
System.out.println(Array[i]);
}
sortedArray = new Sort(Array, sizeOfArray);
sortedArray.display();
}
}
public class Sort
{
int[] array;
int sizeOfArray;
public Sort(int[] oldArray, int sizeOfOldArray)
{
sizeOfArray = sizeOfOldArray;
array = new int [sizeOfArray];
for( int i = 0; i < sizeOfArray; i++)
{
array[i] = oldArray[i];
}
sort();
}
public void display()
{
for ( int i = 0; i < sizeOfArray; i++){
System.out.println(array[i]);
}
}
private void sort()
{
for (int i = 0; i < sizeOfArray; i++)
{
for (int j = 0; j < sizeOfArray; i++)
{
if (array[j] < array[i])
{
swap(i,j);
}
}
}
}
private void swap(int x, int y)
{
int temp;
temp = array[x];
array[x] = array[y];
array[y] = temp;
}
}
I get the error when I run the program and enter the value. The program is supposed to sort the numbers from greatest to least. I'm not sure what is wrong.
First, what it means: you have an array and are trying to acces an index that is outside its range (below 0 or bigger or equal than the length of the array).
The probable cause is:
for (int j = 0; j < sizeOfArray; i++)
Notice that you check that j does not get too big but you are increasing i.
The Problem is that the inner loop also incrementsi which isn't correct in this situation!
private void sort()
{
for (int i = 0; i < sizeOfArray; i++)
{
for (int j = 0; j < sizeOfArray; j++)
{
if (array[j] < array[i])
{
swap(i,j);
}
}
}
}
Your problem is on this line
for (int j = 0; j < sizeOfArray; i++)
it should be
for (int j = 0; j < sizeOfArray; j++)
I'm trying to create a matrix of random double numbers. The matrix must be of size n x n and all numbers must be between 1 and 100. I've been trying to sort it out for ages now and I know it must be something so simple (as it usually is).
Here is my code:
public static void main(String[] args) {
PrintRandomGraph(RandomArray(4));
}
private static double[] RandomArray(int n) {
double[] randomArray = new double[n];
double[][] randomMatrix = new double [n][n];
Random rand = new Random();
rand.setSeed(System.currentTimeMillis());
for (int i = 0; i < n; i++) {
Integer r = rand.nextInt()% 100;
randomArray[i] = Math.abs(r);
for (int j = 0; j < n; j++) {
Arrays.fill(randomMatrix, i, i+1, randomArray);
}
}
return randomArray;
}
private static void PrintRandomGraph(double[] inputArray) {
int n = inputArray.length;
double[] showArray = new double[n];
double[][] showMatrix = new double [n][n];
for (int j = 0; j < n; j++) {
for (int i = 0; i < n; i++) {
double r = inputArray[i];
showArray[i] = r;
Arrays.fill(showMatrix, i, i+1, showArray);
}
}
System.out.println(Arrays.deepToString(showMatrix));
}
When I run the code I get a random array repeated n times like :
[[63.0, 97.0, 64.0, 75.0], [63.0, 97.0, 64.0, 75.0], [63.0, 97.0, 64.0, 75.0], [63.0, 97.0, 64.0, 75.0]]
I think I need to go back to the top of the for loop and add the new array...? Please help =(
Any help is much appreciated. Thank you.
Did you try something like this:
private static double[][] RandomArray(int n) {
double[][] randomMatrix = new double [n][n];
Random rand = new Random();
rand.setSeed(System.currentTimeMillis());
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
Integer r = rand.nextInt()% 100;
randomMatrix[i][j] = Math.abs(r);
}
}
return randomMatrix;
}
to Print the graph:
public void printGraph(double[][] array, int n) {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
System.out.println(array[i][j]);
}
}
}
To Print Graph with Square brackets:
public void printGraph(double[][] array, int n) {
for (int i = 0; i < n; i++) {
System.out.print(" [ ");
for (int j = 0; j < n; j++) {
System.out.print(array[i][j]);
}
//Put println instead of print here to have each row in a new line
System.out.print(" ]");
}
}
Also, this seems a lot like homework, if it is, please tag it like so :)
Hi all this provides the answer I was looking for
private static double[][] RandomArray(int n) {
double[][] randomMatrix = new double [n][n];
double[] randomArray = new double [n];
Random rand = new Random();
rand.setSeed(System.currentTimeMillis());
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
Integer r = rand.nextInt()% 100;
randomMatrix[i][j] = Math.abs(r);
}
}
return randomMatrix;
}
public static void main(String[] args){
//PrintRandomGraph(RandomArray(5));
System.out.println(Arrays.deepToString(RandomArray(5)));
}