I'm trying to simplify this Java code by adding arrays, but I'm having difficulty.
The code that I have so far that works:
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Homework4A {
public static void main(String[] args) throws FileNotFoundException {
Scanner scan = new Scanner(System.in);
System.out.print("Enter name of the input file: ");
String fileName = scan.next();
try (Scanner inFile = new Scanner(new FileReader(fileName))) {
char number0 = '0';
char number1 = '1';
char number2 = '2';
char number3 = '3';
char number4 = '4';
char number5 = '5';
char number6 = '6';
char number7 = '7';
char number8 = '8';
char number9 = '9';
int count0 = 0;
int count1 = 0;
int count2 = 0;
int count3 = 0;
int count4 = 0;
int count5 = 0;
int count6 = 0;
int count7 = 0;
int count8 = 0;
int count9 = 0;
while (inFile.hasNextLine()) {
String line = inFile.nextLine();
for (int i = 0; i < line.length(); i++) {
if (line.charAt(i) == number0) {
count0++;
}
else if (line.charAt(i) == number1) {
count1++;
}
else if (line.charAt(i) == number2) {
count2++;
}
else if (line.charAt(i) == number3) {
count3++;
}
else if (line.charAt(i) == number4) {
count4++;
}
else if (line.charAt(i) == number5) {
count5++;
}
else if (line.charAt(i) == number6) {
count6++;
}
else if (line.charAt(i) == number7) {
count7++;
}
else if (line.charAt(i) == number8) {
count8++;
}
else if (line.charAt(i) == number9) {
count9++;
}
}
}
System.out.println("\n-= Count of Thistles in =-");
System.out.println("-= the Hundred Acre Wood =-\n");
System.out.println(" -----------");
System.out.println(" type count");
System.out.println(" -----------");
System.out.println(" 0 " + count0);
System.out.println(" 1 " + count1);
System.out.println(" 2 " + count2);
System.out.println(" 3 " + count3);
System.out.println(" 4 " + count4);
System.out.println(" 5 " + count5);
System.out.println(" 6 " + count6);
System.out.println(" 7 " + count7);
System.out.println(" 8 " + count8);
System.out.println(" 9 " + count9);
System.out.println(" -----------");
}
}
}
However, it's kind of a brute-force attack. The spot of difficulty I'm running into is figuring out where to create and pass arrays. Since the code has to read the external file, should the arrays be created and passed in the while statement?
For further reference, the text file that is being read looks like this:
Thistle Map
The goal is to count the occurrences of digits only.
As you stated, you could use arrays.
I would suggest 2 arrays
One to hold the digits to catch
Second one for the counts
Initialization of the arrays
char[] numbers = new char[10];
//initialize of numbers(char) to count
for(int i = 0; i < numbers.length; i++) {
numbers[i] = (char) ('0' + i);
}
int[] counts = new int[10]; //no initialization needed because int is default 0
In the for-loop where you iterate over the line, add a nested for loop, that iterates over the numbers-array. Here is the whole while loop:
while (inFile.hasNextLine()) {
String line = inFile.nextLine();
for (int i = 0; i < line.length(); i++) {
for(int j = 0; j < numbers.length; j++) {
if(line.charAt(i) == numbers[j]) {
counts[j]++;
}
}
}
}
For the output just use another for over the arrays:
for(int i = 0; i < numbers.length; i++) {
System.out.println(" "+ numbers[i] +" " + counts[i]);
}
Edit: Another solution using a Map
//...
Map<Character, Integer> charCounts = new HashMap<>();
for (int i = 0; i < 10; i++) {
charCounts.put((char) ('0' + i), 0);
}
while (inFile.hasNextLine()) {
String line = inFile.nextLine();
for (int i = 0; i < line.length(); i++) {
charCounts.computeIfPresent(line.charAt(i), (key, val) -> val + 1);
}
}
//...
for (Character number : charCounts.keySet()) {
System.out.println(" " + number + " " + charCounts.get(number));
}
With this solution you can easily extend your program to count any occuring character. Just remove the initialization of the map and add this line below the computeIfPresent.
charCounts.putIfAbsent(line.charAt(i), 1);
With Java 8 you can use Files.lines to get a Stream of all the lines in a file.
Then you can transform the stream to a stream over every char using flatMap and in the end collect it to a map that has the Character as key and the count of the character as value.
try (Stream<String> stream = Files.lines(Paths.get(fileName)) {
Map<Character, Long> charCountMap = stream
.flatMap(line -> line.chars().mapToObj(c -> (char) c))
.collect(Collectors.groupingBy(c -> c, Collectors.counting()));
System.out.println(" 0 " + charCountMap.getOrDefault('0', 0));
} catch (IOException e) {
e.printStackTrace();
}
Probably the way I would do it in a real world scenario, because it's short, but just for practice the other answers are better.
Yes. I would say it can be simplified a great deal with an array. You don't need seperate sentinels for the values, you can check they are in range and then use Character.digit to parse them. Something like,
Scanner scan = new Scanner(System.in);
System.out.print("Enter name of the input file: ");
String fileName = scan.next();
try (Scanner inFile = new Scanner(new FileReader(fileName))) {
int[] count = new int[10];
while (inFile.hasNextLine()) {
String line = inFile.nextLine();
for (int i = 0; i < line.length(); i++) {
if (line.charAt(i) >= '0' && line.charAt(i) <= '9') {
count[Character.digit(line.charAt(i), 10)]++;
}
}
}
System.out.println("\n-= Count of Thistles in =-");
System.out.println("-= the Hundred Acre Wood =-\n");
System.out.println(" -----------");
System.out.println(" type count");
System.out.println(" -----------");
for (int i = 0; i < count.length; i++) {
System.out.printf(" %d %d%n", i, count[i]);
}
System.out.println(" -----------");
}
You can use a single array for this and index notation. Each array index should hold the quantity of digits. Much more clear.
import java.io.FileReader;
import java.io.FileNotFoundException;
import java.util.Scanner;
public class Homework4A {
public static void main(String[] args) throws FileNotFoundException {
Scanner scan = new Scanner(System.in);
System.out.print("Enter name of the input file: ");
String fileName = scan.next();
try (Scanner inFile = new Scanner(new FileReader(fileName))) {
int[] count = new int[10];
while (inFile.hasNextLine()) {
String line = inFile.nextLine();
for (int i = 0; i < line.length(); i++) {
try {
int c = Character.getNumericValue(line.charAt(i));
count[c] += 1;
} catch (Exception e) { }
}
}
System.out.println("\n-= Count of Thistles in =-");
System.out.println("-= the Hundred Acre Wood =-\n");
System.out.println(" -----------");
System.out.println(" type count");
System.out.println(" -----------");
for (int i = 0; i < 10; i++)
System.out.println(" " + i + " " + count[i]);
System.out.println(" -----------");
}
}
}
Related
I want a specific command to print on the same line but it prints on different lines and I can't figure out a simple fix for it.
package lab10;
import java.util.Scanner;
public class PrintArray {
public static void main(String[] args) {
int numItems;
int[] items;
Scanner scan = new Scanner (System.in);
System.out.println("Enter the number of items");
numItems = scan.nextInt();
items = new int [numItems];
if (items.length > 0);{
System.out.println("Enter the value of all items"
+ "(seperated by space):");
for (int i = 0; i < items.length; ++i) {
int val = scan.nextInt();
items[i]= val;
}
}
for (int i = 0; i < items.length; ++i) {
if (i== 0) {
System.out.println("The values are:" + items[i]);
}else {
System.out.println("The values are:" + items[i] + "," + " ");
}
}
}
}
Expected result:
Enter the number of items
3
Enter the value of all items(separated by space):
1 2 3
The values are:1, 2, 3
Actual result:
Enter the number of items
3
Enter the value of all items(separated by space):
1 2 3
The values are:1
The values are:2,
The values are:3,
Instead of i == 0 you want items.length == 0, and "is" not "are". Also, you'll need additional logic to handle joining the values (and use System.out.print to avoid printing a newline). Like,
if (items.length != 0) {
System.out.print("The values are: ");
}
for (int i = 0; i < items.length; ++i) {
if (items.length == 1) {
System.out.print("The value is: " + items[i]);
} else {
if (i != 0) {
System.out.print(", ");
}
System.out.print(items[i]);
}
}
System.out.println();
I think this approach may be cleaner.
StringJoiner joiner = new StringJoiner(", ", "The values are:", "");
if (items.length > 0){
System.out.println("Enter the value of all items"
+ "(seperated by space):");
for (int i = 0; i < items.length; ++i) {
int val = scan.nextInt();
items[i]= val;
joiner.add(items[i]);
}
}
System.out.println(joiner.toString());
BTW, at this line
if (items.length > 0);{
the semicolon(;) should not be there.
I'm currently coding a program that takes in a string and a single character (if you decide to put a single one in that is) and (is supposed) to check how many times that character is in the string and at the end print out the amount of times it is in there. For some reason it isn't working and I would like some help; thank you!
import java.util.Scanner;
public class HowManyChars {
public HowManyChars() {
Scanner sc = new Scanner (System.in);
String askPhrase;
String askChar;
int charCounter = 0;
System.out.println("Enter a phrase");
askPhrase = sc.nextLine();
System.out.println("Enter a letter");
askChar = sc.nextLine();
for (int i = 0; i < askPhrase.length(); i++) {
if (askPhrase.substring(i, i + 1) == askChar) {
charCounter = charCounter + 1;
}
}
System.out.println("There are " + charCounter + " " + askChar + " in " + askPhrase);
}
}
I give credit for this answer to #Mushif, who correctly figured out the problem. Your current comparison logic is comparing a string against a character:
for (int i=0; i < askPhrase.length(); i++) {
// String char
if (askPhrase.substring(i, i + 1) == askChar) {
charCounter = charCounter + 1;
}
}
Try iterating the character set of the input word and then compare apples to apples:
for (int i=0; i < askPhrase.length(); i++) {
if (askPhrase.charAt(i) == askChar) {
charCounter = charCounter + 1;
}
}
You could also use an enhanced loop directly on the input's character set:
for (char chr : askPhrase.toCharArray()) {
if (chr == askChar) {
charCounter = charCounter + 1;
}
}
import java.util.Scanner;
public class HowManyChars {
public HowManyChars() {
Scanner sc = new Scanner (System.in);
String askPhrase;
char askChar;
char[] askChars;
int charCounter = 0;
System.out.println("Enter a phrase");
askPhrase = sc.nextLine();
askChars = askPhrase.toCharArray();
System.out.println("Enter a letter");
askChar = sc.next().charAt(0);
sc.close();
for (int i = 0; i < askChars.length; i++) {
if (Character.toLowerCase(askChar) == Character.toLowerCase(askChars[i])) {
charCounter ++;
}
}
System.out.println("There are " + charCounter + " " + askChar + " in " + askPhrase);
}
}
Array out of bounds ? i'm trying to perform the output in the picture:
Using this INPUT
"JAVA IS A PROGRAMMING LANGUAGE"
This is my code so far
import java.util.Scanner;
public class Main
{
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
System.out.print("Input Phrase:");
String s = in.nextLine();
String[] word=s.split(" ");
String rts=" ";
for(int i=0;i<word.length;i++){
if(word[i].length()>=rts.length()){
rts=word[i];
}
}
int thisislength = rts.length();
for (int a = 0; a < thisislength ;a++ ) {
for (int b = 0; b < word.length ;b++ ) {
System.out.print(word[b].charAt(a)+" ");
}
System.out.println();
}
}
}
When the second word reaches its last letter it doesn't continue the for loop, is there any way to continue the loop even if the second word reaches its max length.
< should have been <=. Reversing left and right hand sides makes it more readably I think.
for (int a = 0; a < thisislength; a++) {
System.out.printf("%3d ", a+1);
for (int b = 0; b < word.length; b++) {
if (a >= word[b].length()) {
System.out.print(' ');
} else {
System.out.print(word[b].charAt(a));
}
System.out.print(' ');
}
System.out.println();
}
Or instead of the if-else statement:
for (String w : word) {
System.out.print(a >= w.length() ? ' ' : w.charAt(a));
}
This gives the result you want:
for (int a = 0; a < thisislength ;a++ ){
for (int b = 0; b < word.length ;b++ ){
if(word[b].length() < a + 1){
System.out.print(" ");
}else{
System.out.print(word[b].charAt(a) + " ");
}
}
System.out.println();
}
This line was changed:
if(word[b].length() < a + 1) and not if(word[b].length() < a)
and 2 spaces print in the if statement
TRY THIS SOLUTION HOPE IT WILL HELP YOU :
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class Main
{
public static void main(String[] args) {
// GET VALUE FROM THE CONSOLE
Scanner in = new Scanner(System.in);
System.out.print("Input Phrase:");
String s = in.nextLine();
// SPLIT STRING TO WORDS
String[] words = s.split(" ");
// CREATE A LIST OF CHAR_ARRAY CALLED : matrix
List<char[]> matrix = new ArrayList<char[]>();
// REFERENCE THE LARGEST WORD IN WORDS ARRAY EX : PROGRAMMING IS THE LARGEST
int max = 0;
// FILL OUR LIST OF ARRAY OF CHARS
for (int b = 0; b < words.length ;b++ ) {
char[] chars = words[b].toCharArray();
max = (chars.length >= max)? chars.length : max ;
matrix.add( chars );
}
// PRINT OUR CHAR
for (int a = 0; a < max ;a++ ) {
for (int b = 0; b < words.length ;b++ ) {
if(a < matrix.get(b).length) {
System.out.print(matrix.get(b)[a]);
System.out.print(" ");
}else {
System.out.print(" ");
System.out.print(" ");
}
}
System.out.println("");
}
}
}
So I have to read a sequence of numbers from the console ( 1 to 50 numbers), none of which are equal and print out the numbers for which is true that a|b == c|d (example: 5|32 == 53|2), but I get an NubmferFormatException each time. Why?
import java.util.Scanner;
public class StuckNumbers {
public static void main(String[] args) {
// create Scanner
Scanner input = new Scanner(System.in);
// input count and declare array
System.out.println("input number of numbers");
int count = input.nextInt();
int[] numbers = new int[count];
// check if count is between 1 and 50
if (count < 1 && count > 50) {
System.out.println("Wrong input. Input a number between 1 and 50");
count = input.nextInt();
}
// input n numbers
for (int i : numbers) {
i = input.nextInt();
// check if i = j
for (int j : numbers) {
if (i == j) {
System.out
.println("All numbers must be dist75inct. Try again.");
i = input.nextInt();
}
}
}
for (int i = 0; i < count; i++) {
for (int j = 0; j < count; j++) {
if (stuckNumbers(numbers[i], numbers[j]) == stuckNumbers(
numbers[j], numbers[i])) {
System.out.println(i + "|" + j + " == " + j + "|" + i);
}
}
}
input.close();
}
public static int stuckNumbers(int a, int b) {
String firstNum = "a";
String secondNum = "b";
String res = "ab";
int result = Integer.parseInt(res);
return result;
}
}
Look at these lines:
String res = "ab";
int result = Integer.parseInt(res);
"ab" is not a number, so you're going to get a NumberFormatException when you try to parse it as an integer.
Change the firstNum and SecondNum variables from "a" and "b" to Integer.toString(a); OR String.valueOf(a); and similar for b.
public static int stuckNumbers(int a, int b) {
String firstNum = String.valueOf(a);
String secondNum = String.valueOf(b);
String res = "";
res.concat(firstNum);
res.concat(secondNum);
int result = Integer.parseInt(res);
return result;
}
I hope this will remove any Exception being thrown.
I have a program for a hangman game and the indexof is not working for me? its on line 30. I have been trying to figure it out but I cannot.if (guessedWord.indexOf(letter) >= 0). I will keep trying to find out what I did wrong
import java.io.PrintStream;
import java.util.Scanner;
public class Hangman
{
public static void main(String[] args)
{
String[] words = { "write", "program", "that", "receive", "positive" };
Scanner input = new Scanner(System.in);
char anotherGame;
do
{
int index = (int)(Math.random() * words.length);
String hiddenWord = words[index];
StringBuilder guessedWord = new StringBuilder();
for (int i = 0; i < hiddenWord.length(); i++) {
guessedWord.append('*');
}
int numberOfCorrectLettersGuessed = 0; int numberOfMisses = 0;
while (numberOfCorrectLettersGuessed < hiddenWord.length()) {
System.out.print("(Guess) Enter a letter in word " + guessedWord +
" > ");
String s = input.nextLine();
char letter = s.charAt(0);
if (guessedWord.indexOf(letter) >= 0) {
System.out.println("\t" + letter + " is already in the word");
} else if (hiddenWord.indexOf(letter) < 0) {
System.out.println("\t" + letter + " is not in the word");
numberOfMisses++;
} else {
int k = hiddenWord.indexOf(letter);
while (k >= 0) {
guessedWord.setCharAt(k, letter);
numberOfCorrectLettersGuessed++;
k = hiddenWord.indexOf(letter, k + 1);
}
}
}
System.out.println("The word is " + hiddenWord + ". You missed " + numberOfMisses + (numberOfMisses <= 1 ? " time" : " times"));
System.out.print("Do you want to guess for another word? Enter y or n> ");
anotherGame = input.nextLine().charAt(0);
}while (anotherGame == 'y');
}
}
You are passing in a char where String is expected. Try using String.valueOf(letter) like this:
if (guessedWord.indexOf(String.valueOf(letter)) >= 0) {
// Your code
}
StringBuilder#indexOf(char) is undefined. You could do
if (guessedWord.indexOf(Character.toString(letter)) >= 0) {
there's no indexOf(char) method for a StringBuilder.
guessedWord.indexOf(letter)
should be
if (guessedWord.toString().indexOf(letter) >= 0) {