.equals() in java dosent work? There is a problem with my program, for some reason in the while loop part it is always active even if the String a = answer[r]
import java.util.Scanner;
public class security {
static Scanner sc = new Scanner(System.in);
public static void main(String[] args) {
String q1[] = {"mother midd name","Father name","your pit name","First school name"};
String a[] = {"Zakia","Mohamed","Dog","Kaliop"};
AskQ(q1,a);
}
public static void AskQ(String q[],String answers[]) {
int r = (int) (Math.random() * q.length) + 1;
for (int i = 0; i < answers.length; i++) {
int c = 1;
System.out.print("please enter your " + q[r] + "?");
String a = sc.nextLine();
do {
c++;
System.out.print("Wrong! try again:");
a = sc.nextLine();
if(c == 2){
System.out.print("only one attempt lift! enter your pass:");
a = sc.nextLine();
c++;
}
if(c == 3){
System.exit(0);
}
c++;
} while (!a.equals(answers[r]));
System.out.println("you are in");
break;
}
}
}
From what I am seeing, your code first sets c equal to 1 in the for-loop, then asks for an answer to a question, then goes into the do-while loop. Inside of the do-while loop it increments c to 2, then takes in another answer to a question, then checks to see if c is equal to 2. Since c is equal to 2 it asks for an aswer to another question then it increments c to 3. Finally, it checks to see if c is equal to 3 (which it is) and exits the program.
I suggest using a while loop over a do-while loop since it looks like you want to check to see if the user entered in the correct answer BEFORE you do any checking and error-handling. If you use a do-while loop, you are doing the error handling before it ever even checks to see if the user entered in the correct answer.
More over, i'd suggest using your second if-statement as an else-if statement.
Related
i want to make a program which related to this question:
An integer that can be expressed as the square of another integer is called a perfect square, such as 4,9,16,25, etc. Write a progran that checks if a number is a perfect square.
I did built something goes like:
import java.util.Scanner;
class Q3{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
int num = 0;
int a = 0;
System.out.println("Type a number to check if it has square");
num = sc.nextInt();
for(a = 1;a<num;a++){ }
if (a*a == num){
System.out.println("Ok");
break;
}
else if (a*a != num){
System.out.println("Not ok");
}
}
}
So it doesn’t give what i want when i run it. What should i change or add ?
I think your for loop interpretation might be wrong, I made up something that might just work. Give this code a try.. You can make the method return a boolean too if you want.
static void perfectSquare(int number) {
for (int i = 1; i < i * number; ++i) {
// 'i' is the divisor, making sure
// it is equal to the quotient
if ((number % i == 0) && (number / i == i)) {
System.out.println(i);
}
}
If you want to brute force every number then you are on the right track but you should only print "Not ok" if all numbers in the loop have failed otherwise you may have a perfect square but "Ok" will be hidden within many "Not ok" lines. Also there is nothing in your for loop so the if statement always checks if 0*0 == num.
This looks like it may be a homework question so I won't give a full answer for you but think about how you can make this more efficient.
If you have found an integer number that matches do you need to keep going?
Do you need to check every number? (a starting point may be following the principles of a binary search)
I ended up like this:
import java.util.Scanner;
class Q3{
public static void main(String[] args){
Scanner sc = new Scanner(System.in);
int num = 0;
int a = 0;
int b = 0;
System.out.println("Type a number to check if it has square");
num = sc.nextInt();
for(a = 1;a<num;a++){
if (a*a == num){
b = 1;
break;
}
}
if(b==1){
System.out.println("Perfect Square");
}
else {
System.out.println("Not ok");
}
}
}
Thanks for support !
I am a beginner and as you can see I made a simple Java game.
The user has 5 tries to guess a number between 1 and 20.
If the user wins a congratulations message will show.
If the user didn't succeed a game over message will pop up.
Issue
When the user enters the right answer on the 5th try both congratulations and game over messages will pop up.
Code
package org.meicode.Loops;
import java.util.Objects;
import java.util.Random;
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
System.out.println("Welcome");
System.out.println("Enter your name please ");
Scanner scanner = new Scanner(System.in);
String name = scanner.next();
System.out.println("Hello " + name);
System.out.println("Type 1 to start the game");
int yes = scanner.nextInt();
while (yes != 1) {
System.out.println("Type 1 to start the game");
yes = scanner.nextInt();
}
System.out.println("Guess the number in my mind,It is between 1 and 20 and you got 5 tries");
int timestried = 0;
Random random = new Random();
int x = random.nextInt(20) + 1;
while (timestried < 5) {
timestried++;
Scanner scanner1 = new Scanner(System.in);
int answer = scanner.nextInt();
if (x == answer) {
System.out.println("Well done, you did it");
} else if (x > answer) {
System.out.println("Try again,hint:the value is bigger than what you typed");
} else if (x < answer) {
System.out.println("Try again,hint:the value is smaller than what you typed");
}
}
System.out.println("Game over, the number was " + x);
}
}
How can I fix it?
Here is my attempt. I have added some comments in the code to help you.
Note that I have changed some of the file names to, so you may need to change them back for it to run, or just copy the main code section:
package com.misc;
import java.util.Objects;
import java.util.Random;
import java.util.Scanner;
public class GameTest {
public static void main(String[] args) {
System.out.println("Welcome");
System.out.println("Enter your name please ");
Scanner scanner = new Scanner(System.in);
String name = scanner.next();
System.out.println("Hello " + name);
System.out.println("Type 1 to start the game");
int yes = scanner.nextInt();
//We initialize the answer variable here to use it later on.
int answer = 0;
while (yes != 1) {
System.out.println("Type 1 to start the game");
yes = scanner.nextInt();
}
System.out.println("Guess the number in my mind,It is between 1 and 20 and you got 5 tries");
int timestried = 0;
Random random = new Random();
int x = random.nextInt(20) + 1;
//Print out the randomly generated number so we can test it. We answer wrong 4 times then put in the right answer to see if the message is fixed.
System.out.println("Testing: the answer is " + x);
while (timestried < 5) {
timestried++;
Scanner scanner1 = new Scanner(System.in);
answer = scanner.nextInt();
if (x == answer) {
System.out.println("Well done, you did it");
} else if (x > answer) {
System.out.println("Try again,hint:the value is bigger than what you typed");
} else if (x < answer) {
System.out.println("Try again,hint:the value is smaller than what you typed");
}
}
//This is the conditional that uses the answer variable we declared earlier above to avoid printing out the Game Over message in a success scenario.
if (x != answer) {
System.out.println("Game over, the number was " + x);
}
}
}
Here is proof that it works. I made the program print out the real answer, answered wrong 4 times and correctly the 5th time.
Simple fix
There are 2 things I would add to your code to achieve the desired behavior:
break or exit the loop on correct answer
set a flag signaling the question was solved to later build the message upon it
Basics: How to break loops and why
You can achieve this by two ways:
break the loop when the user typed the correct answer
add an exit-condition to the loop
return from the whole method prematurely
throw an exception that can either be caught outside or will also exit the method
I will explain (1) and (2) here in this answer (3) in a separate answer.
(1) Breaking the loop
The loop shall continue until:
the maximum number of tries has been reached
the correct answer was given
Use a break; statement to break the loop if correct answer:
if (x == answer) {
System.out.println("Well done, you did it");
break;
}
Note: contrary a continue; will skip further loop-body and jump to the next iteration.
(2) add a flag signaling premature exit (e.g. correct answer)
You can add a flag that is set to true if the user types the correct answer:
boolean userHasAnsweredCorrect = false;
while (timesTried < 5) { // here the flag can be added instead breaking
if (x == answer) {
System.out.println("Well done, you did it");
userHasAnsweredCorrect = true;
break;
}
}
// omitted some lines .. then at the end
if (userHasAnsweredCorrect) {
System.out.println("You beat the game!")
} else {
System.out.println("Game over, the number was " + x);
}
See how you define the flag before the loop, set it inside the loop (together with a break;) and then test on the flag after the loop.
Combined: set flag and add exit-condition
boolean userHasAnsweredCorrect = false;
while (timesTried < 5 && !userHasAnsweredCorrect) { // here the break happens instead
if (x == answer) {
System.out.println("Well done, you did it");
userHasAnsweredCorrect = true;
// break;
}
}
Find 2 more simpler ways of breaking the loop in my other answer, here follows the 3rd way:
Put the whole game into a method like startGame() and exit from that. Either exit after loop with max-tries has finished or inside the loop (prematurely) if answered guess was correct.
(3) Exiting the loop and method using return
That premature method-exit can be achieved by inserting a return; inside the loop.
public void startGame() {
// rest of preparation
// starting the game-loop
for (int i = 1; i <= maxTries; i++) { // for-i is indexed and safer (no infinite-loop)
// read input
// score or evaluate answer against x
if (x == answer) {
System.out.println("Well done, you did it");
return; // exit the method, not reaching "game-over" after the loop
}
// continue the iteration
}
// game-over (if not previously exited because of victory)
}
To have an exit-condition for the for loop, define int maxTries = 5 either as local variable, class field or constant.
For a Java exercise I'm writing a program where the user enters two strings. The program then checks to see if the two strings share any similar characters and outputs them to the screen.
For example is Terrarium and Terraform are the two strings it should print t e r r a r. However when I run my program it always simply outputs all the characters in the first string. (In this case T e r r a f o r m.)
I suspect I'm creating a logical error based on a limited understanding of loops. But when I search for answers people seem to always use a similar method to my own.
Here is the code for your viewing:
import java.util.Scanner;
public class CountMatches
{
public static void main(String[] args)
{
Scanner keyboard = new Scanner(System.in);
System.out.println(" Please enter a String >> ");
String stringA = keyboard.nextLine();
System.out.println(" Please enter another String >> ");
String stringB = keyboard.nextLine();
for(int counter = 0; counter < stringA.length(); counter++ )
{
char compareA = stringA.charAt(counter);
char compareB = stringB.charAt(counter);
//System.out.println(compareA);
//System.out.println(compareB);
//System.out.println("");
if(compareA != compareB)
{
System.out.println("");
}
else if(compareA == compareB);
{
System.out.println(compareA);
System.out.println("");
}
}
}
}
else if(compareA == compareB);
Get rid of the semicolon on this line and it should work. I would also get rid of the first if statement just keep the second one.
You have two problems with this code.
First,
for(int counter = 0; counter < stringA.length(); counter++ )
If the two string are of different length, you could get an exception by going off the end of the other string. So, do this:
int len = stringA.length();
if (len > stringB.lengh()) len = stringB.length();
Next, the reason you code fails is because you have a ; at the end of your else. Your code should be:
if(compareA != compareB)
{
System.out.println("");
}
else // Don't need the == here
{
System.out.println(compareA);
System.out.println("");
}
Good luck with this.
I have tried to find guidance on this, but I keep getting solutions on an entire string, or a single character. I am in my 4th week of Java, and have hit a roadblock.
I have to ask a user to input three letters ("Enter three letters: abc"). Depending on which case they type, I have to write a program that swaps upper with lower and visa versa. For example, if the user types "aBc", my output will be "AbC".
This is what I have so far. If my code is horrible, I'm sorry. I'm learning as I go.
import java.util.Scanner;
public class LowerUpper {
public static void main(String[]args) {
Scanner input = new Scanner(System.in);
System.out.print("Please enter three letters: ");
String letters = input.nextLine();
for (int i = 0; i < letters.length(); i++) {
char letter1 = letters.charAt(0);
char letter2 = letters.charAt(1);
char letter3 = letters.charAt(2);
if (Character.isUpperCase(letters.charAt(0)) == true)
System.out.println(Character.toLowerCase(letter1));
else {
System.out.println(Character.toUpperCase(letter1));
}
if (Character.isUpperCase(letters.charAt(1)) == true)
System.out.println(Character.toLowerCase(letter2));
else {
System.out.println(Character.toUpperCase(letter2));
}
if (Character.isUpperCase(letters.charAt(2)) == true)
System.out.println(Character.toLowerCase(letter3));
else {
System.out.println(Character.toUpperCase(letter3));
}
}
}
}
When I typed "abc" for the input, the output was:
A
B
C
A
B
C
A
B
C
The format of the output is supposed to be "Result: ABC". I can work on that later. I'm just trying to figure out how to get this to execute correctly. My hunch is that I'm definitely going wrong on my if/else statements. I do not know how to print the changed chars all in a row (abc, AbC, ABC, etc). I thought I did it correctly at the beginning with the indexing of the string (0,1,2).
By the way, it's not showing my output correctly this forum. It is supposed to be one letter per line, not "ABCABCABC", if I made sense with that.
The reasoning for this is because it's inside of a for loop, which is essentially worthless, because you are never using the integer 'i'. If you remove the for loop, it should only execute once, thus for outputting "ABC", instead of "A B C A B C A B C". To print the chars in a row, you can simply append each character to a string, and then output that.
The biggest issue I see is that you've got a loop going over the length of the string but you're not using the loop index i to reference the individual characters. In short, you're trying too hard and overlooking the obvious.
Wouldn't this do the trick?
for (int i = 0; i < letters.length(); i++) {
char letter1 = letters.charAt(0);
if (Character.isUpperCase(letter1)) {
System.out.println(Character.toLowerCase(letter1));
} else {
System.out.println(Character.toUpperCase(letter1));
}
}
The reason why you get a redundant printing 'coz you loop the three variables which already contain all characters.
To solve your problem. just remove the for loop. 'coz you already
store each character to the three variables.
You code will look like this now:
import java.util.Scanner;
public class LowerUpper {
public static void main(String[]args) {
Scanner input = new Scanner(System.in);
System.out.print("Please enter three letters: ");
String letters = input.nextLine();
char letter1 = letters.charAt(0);
char letter2 = letters.charAt(1);
char letter3 = letters.charAt(2);
if (Character.isUpperCase(letters.charAt(0)) == true)
System.out.println(Character.toLowerCase(letter1));
else {
System.out.println(Character.toUpperCase(letter1));
}
if (Character.isUpperCase(letters.charAt(1)) == true)
System.out.println(Character.toLowerCase(letter2));
else {
System.out.println(Character.toUpperCase(letter2));
}
if (Character.isUpperCase(letters.charAt(2)) == true)
System.out.println(Character.toLowerCase(letter3));
else {
System.out.println(Character.toUpperCase(letter3));
}
}
}
Ok, here is my new code. It compiled with no errors and the output was just as it was supposed to be:
import java.util.Scanner;
public class LowerUpper {
public static void main(String[]args) {
Scanner input = new Scanner(System.in);
System.out.print("Please enter three letters: ");
String letters = input.nextLine();
char letter1 = letters.charAt(0);
char letter2 = letters.charAt(1);
char letter3 = letters.charAt(2);
if (Character.isUpperCase(letters.charAt(0)) == true)
System.out.print("Result: " + Character.toLowerCase(letter1));
else {
System.out.print("Result: " + Character.toUpperCase(letter1));
}
if (Character.isUpperCase(letters.charAt(1)) == true)
System.out.print(Character.toLowerCase(letter2));
else {
System.out.print(Character.toUpperCase(letter2));
}
if (Character.isUpperCase(letters.charAt(2)) == true)
System.out.print(Character.toLowerCase(letter3));
else {
System.out.print(Character.toUpperCase(letter3));
}
}
}
The problem is that you have a loop then do each letter individually. So get rid of the loop. It would look better if you re-wrote it with a loop but only had one if/else statement inside the loop based on i not 0,1&2.
Replace your for loop with:
System.out.println(letters.toUpperCase());
In the program given I have to make sure that if two consequtive characters are the same. I shouldn't increase the value of the variable (Count)... I have tried "break;", but that skips me out of the "for loop" which is very counter-productive. How can I skip the given part and still continue the "for loop"?
Currently my output for "Hello//world" is 3. It should be 2 (the '/' indicates a ' '(Space)).
Code
import java.util.Scanner;
class CountWordsWithEmergency
{
public static void main()
{
Scanner input = new Scanner(System.in);
System.out.println("Please input the String");
String inp = input.nextLine();
System.out.println("thank you");
int i = inp.length();
int count = 1;
for(int j=0;j<=i-1;j++) //This is the for loop I would like to stay in.
{
char check = inp.charAt(j);
if(check==' ')
{
if((inp.charAt(j+1))==check) //This is the condition to prevent increase for
//count variable.
{
count = count; //This does not work and neither does break;
}
count++;
}
}
System.out.println("The number of words are : "+count);
}
}
You can use the keyword continue in order to accomplish what you are trying to do.
However you can also inverse your conditional test and use count++ only if it is different (!= instead of == in your if) and do nothing otherwise
if ((inp.charAt(j+1)) != check) {
count++;
}
The word you are looking for is "continue".
Try this:
if ((inp.charAt(j+1)) != check) {
count++;
}
Increment the value of count by checking with !=.
Try using continue where you want to skip an block.
Use "continue;" when you want to break the current iteration.
continue is a keyword in java programming used to skip the loop or block of code and reexecutes the loop with new condition.
continue statement is used only in while,do while and for loop.
You may want to use the continue keyword, or modify the logic a little bit:
import java.util.Scanner;
class CountWordsWithEmergency
{
public static void main()
{
Scanner input = new Scanner(System.in);
System.out.println("Please input the String");
String inp = input.nextLine();
System.out.println("thank you");
int i = inp.length();
int count = 1;
for(int j=0;j<=i-1;j++) //This is the for loop I would like to stay in.
{
char check = inp.charAt(j);
if(check==' ')
{
if((inp.charAt(j+1))!=check)
{
count++;
}
}
}
System.out.println("The number of words are : "+count);
}
}
Edit:
You may want to use the split method of the String class.
int wordsCount = str.split(' ').length;
Hope it helps :)
The following should work.
import java.util.Scanner;
class CountWordsWithEmergency
{
public static void main()
{
Scanner input = new Scanner(System.in);
System.out.println("Please input the String");
String inp = input.nextLine();
System.out.println("thank you");
int i = inp.length();
int count = 1;
for(int j=0;j<=i-1;j++) //This is the for loop I would like to stay in.
{
char check = inp.charAt(j);
if(check==' ')
{
if((inp.charAt(j+1))==check) //This is the condition to prevent increase for
//count variable.
{
continue;
}
count++;
}
}
System.out.println("The number of words are : "+count);
}
}