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Trying to create a gridgenerator in java: [closed]

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I'm trying to create a program as described in the image linked below. I'm finding trouble with how to print the characters on the same line so that I can get 20 across and how to go to a new line after the first 20 characters have printed. Can you help me figure out a way to print the randomly selected characters into a 20 by 7 grid? Thank you for the help! Below is what I have so far but it's printing every new character on its own line and for gridArray[3] the forward-slash has to have two quotes otherwise it says that it's not a valid string. Does anyone know how I could solve these problems?
Link to Problem Directions
package edu.skidmore.cs106.lab09.problem14;
import java.util.Random;
public class GridGenorator {
public static void main(String[] args) {
// TODO Auto-generated method stub
String[] gridArray = new String[6];
gridArray[0] = "+";
gridArray[1] = "-";
gridArray[2] = "/";
gridArray[3] = "\"";
gridArray[4] = "|";
gridArray[5] = "_";
for (int elementx = 0; elementx < 7; elementx++) {
for(int elementy = 0; elementy<20; elementy++) {
Random rand = new Random();
int randomNum = rand.nextInt(6);
System.out.println(gridArray[randomNum]);
}
}
}
}

System.out.println prints a new line which you do not want to do every time, only after a group of 20, so try
for (int elementx = 0; elementx < 7; elementx++) {
for(int elementy = 0; elementy<20; elementy++) {
Random rand = new Random();
int randomNum = rand.nextInt(6);
System.out.print(gridArray[randomNum]);
}
System.out.println(); // now you want to print a newline
}

ReverseString program [closed]

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I'm trying to make a ReverseString program. It's only returning one word only. I would like a full sentence.
import java.util.Scanner;
public class ReverseString {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String word = input.next();
String reverse = "";
for (int i = word.length() - 1; i >= 0; i--)
reverse += word.charAt(i);
System.out.println(reverse);
}
}

You can use the reverse method of the StringBuilder/StringBuffer class.
Something like :
String reversedString = new StringBuilder(input.nextLine()).reverse().toString();
Or if you want a more low-level approach you could use a Stack push every character in it and pop it one by one to get the reversal of it.
public String reverseString(String s) {
Stack<Character> stack = new Stack<>();
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < s.length(); i++) {
stack.push(s.charAt(i));
}
while (!stack.empty()) {
stringBuilder.append(stack.pop());
}
return stringBuilder.toString();
}

I want to make a program in which when I press the button the text changes [closed]

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It is an android app.
Text is stored in an array. It should change serial wise
Here is what I had done before.
String name = "";
String names[] = {"A", "B", "C", "D"};
int counter = 0;
name = names[counter];
counter++;
if(counter >= 3)
{
counter = 0;
}
return name;
I was doing something like that before. I know it totally incorrect . But something like this I wanted to do.

This may help solve your problem.
import java.util.Scanner;
public class Main {
static int currentIndex = 0;
static String[] words = {"word1", "word2", "word3"};
public static void main(String[] args) {
while(true) {
Scanner keyboard = new Scanner(System.in);
String input = keyboard.nextLine();
if(input != null){
System.out.println(words[currentIndex++]);
if(currentIndex == words.length){
currentIndex = 0;
}
}
}
}
}

Getting Ljava.lang.String;# in my output while iterating through a string [closed]

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Closed 6 years ago.
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so I have to write a program for an assignment, and for that i have to accept a string, make sure it's got the right number of sentences and print the frequency of each word. I've got this almost completely right, but at the end, when I print the words (which I've stored in an array), each word is preceeded by Ljava.lang.String; #xyznumber. I have no idea why this is happening and I can't find a solution on the net. Here's my code:
import java.util.Arrays;
import java.io.*;
class frequency
{
public static void main(String args[])throws IOException
{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter the number of sentences");
int cS = Integer.parseInt(br.readLine());
System.out.println("Enter sentences");
String s = br.readLine();
int cS1 = 0;
int cW = 0;
for(int i = 0; i < s.length(); i++)
{
char ch = s.charAt(i);
if (ch=='.'||ch=='?')
{
cW++;
cS1++;
}
if (ch==' ')
{
cW++;
}
}
if (cS1!=cS)
{
System.out.println("You have entered the wrong number of sentences. Please try again.");
}
else
{
int c = 0;
int d = 0;
String a[] = new String[cW];
System.out.println("Total Number of words: "+cW);
for (int i= 0;i<s.length();i++)
{
char ch=s.charAt(i);
if (ch==' '||ch=='?'||ch=='.')
{
a[c++]=a+s.substring(d,i);
d = i+1;
}
}
int length=0;
firstFor: for(int i=0;i<a.length;i++)
{
for(int j=0;j<i;j++)
{
if (a[j].equalsIgnoreCase(a[i]))
{
continue firstFor;
}
else
{
length++;
}
}
}
String words[] = new String[length];
int counts[] = new int[length];
int k=0;
secondFor: for (int i =0;i<a.length;i++)
{
for(int j = 0; j<i;j++)
{
if (a[j].equalsIgnoreCase(a[i]))
{
continue secondFor;
}
}
words[k]=a[i];
int counter = 0;
for (int j =0;j<a.length;j++)
{
if(a[j].equalsIgnoreCase(a[i]))
{
counter++;
}
}
counts[k]=counter;
k++;
}
for (int i=0;i<words.length;i++)
{
System.out.println(words[i]+"\n"+(counts[i]));
}
}
}
}

The problem stems from this line here:
a[c++]=a+s.substring(d,i);
Since a is a String array, what this does is assigns one of the elements in a to be equal to the String representation of the entire array, plus a substring of s. Arrays don't have a very useful String representation though, which is where the Ljava.lang.String;#xyznumber you see is coming from.
Depending on what you want the first part of a[c] to be, either use an index into the array, or convert the array to a String

Checking if a number is a Happy Number or not Java [closed]

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I'm currently doing a challenge on a website to do with checking if a number is a Happy Number or not. The program is to read in a file with a list of numbers, one on each line and determine if it is a happy number. I'm having some trouble with implementing the check to see if the number is happy or not.
The happy part is fairly straight forward, if it gets to 1 it is a happy number. The problem occurs for me if the number is not happy it will never get to 1 and will stay in an infinite loop so I'm not sure on how to track that successfully
Here is the code:
package com.jconnolly.codeeval;
import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.ArrayList;
public class HappyNumbers {
public static void main(String[] args) {
HappyNumbers hn = new HappyNumbers();
File file = new File(args[0]);
BufferedReader br;
String[] numbers;
try {
// Read in file
br = new BufferedReader(new FileReader(file));
String line;
// Store each line as a string in an array
while((line = br.readLine()) != null) {
numbers = line.split("\n");
for(int i = 0; i < numbers.length; i++) {
if(hn.isHappy(numbers[i])) {
System.out.println(1);
} else {
System.out.println(0);
}
}
}
System.exit(0);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
System.exit(-1);
}
}
// Separates digits, squares them and adds them together
public boolean isHappy(String str) {
int sum = 0;
// Holds numbers after they are squared and added together
ArrayList<Integer> happy = new ArrayList<Integer>();
// Separates the digits to be squared
while((sum != 1) && !happy.contains(sum)) {
for(int i = 0; i < str.length(); i++) {
Character c = new Character(str.charAt(i));
String character = c.toString();
int digit = Integer.parseInt(character);
sum += (digit * digit);
}
happy.add(sum);
}
happy.clear();
return sum == 1;
}
Any advice on a better implementation or correction would be greatly appreciated. It does give results but they are incorrect. Thanks

The only way I can think of to test for "never reaches 1" is to recognize when you're retesting values you've already tested, which would show that you're caught in a loop where all the numbers in that loop are unhappy. Build up a dictionary from there and use it to recognize other unhappy numbers more quickly. I believe that for this formula that's actually practical; for some, it might not be.

Try the following isHappy() method; I think recursion is the most elegant solution, but a list is needed to prevent entering a loop:
ArrayList<Integer> checked = new ArrayList<Integer>(); // used to tell if a number has already been checked
public boolean isHappy(int i) {
if(i == 1)
return true;
for(int j : checked)
if(i == j)
return false
int nextNum = ...; // generate the next number (sum the squared digits of i)
checked.add(nextNum);
return isHappy(nextNum);
}
Hope this helps!