This is my second time asking this question because this assignment is due tomorrow, and I am still unclear how to progress in my code! I am in an AP Computer programming class so I am a complete beginner at this. My goal (so far) is to multiply two fractions. Is there any way to use a variable inside a particular method outside of that method in another method? I hope that wasn't confusing, thank you!!
import java.util.Scanner;
import java.util.StringTokenizer;
public class javatest3 {
static int num1 = 0;
static int num2 = 0;
static int denom1 = 0;
static int denom2 = 0;
public static void main(String[] args){
System.out.println("Enter an expression (or \"quit\"): "); //prompts user for input
intro();
}
public static void intro(){
Scanner input = new Scanner(System.in);
String user= input.nextLine();
while (!user.equals("quit") & input.hasNextLine()){ //processes code when user input does not equal quit
StringTokenizer chunks = new StringTokenizer(user, " "); //parses by white space
String fraction1 = chunks.nextToken(); //first fraction
String operand = chunks.nextToken(); //operator
String fraction2 = chunks.nextToken(); //second fraction
System.out.println("Fraction 1: " + fraction1);
System.out.println("Operation: " + operand);
System.out.println("Fraction 2: " + fraction2);
System.out.println("Enter an expression (or \"quit\"): "); //prompts user for more input
while (user.contains("*")){
parse(fraction1);
parse(fraction2);
System.out.println("hi");
int num = num1 * num2;
int denom = denom1 * denom2;
System.out.println(num + "/" + denom);
user = input.next();
}
}
}
public static void parse(String fraction) {
if (fraction.contains("_")){
StringTokenizer mixed = new StringTokenizer(fraction, "_");
int wholeNumber = Integer.parseInt(mixed.nextToken());
System.out.println(wholeNumber);
String frac = mixed.nextToken();
System.out.println(frac);
StringTokenizer parseFraction = new StringTokenizer(frac, "/"); //parses by forward slash
int num = Integer.parseInt(parseFraction.nextToken());
System.out.println(num);
int denom = Integer.parseInt(parseFraction.nextToken());
System.out.println(denom);
}
else if (!fraction.contains("_") && fraction.contains("/")){
StringTokenizer parseFraction = new StringTokenizer(fraction, "/"); //parses by forward slash
int num = Integer.parseInt(parseFraction.nextToken());
System.out.println(num);
int denom = Integer.parseInt(parseFraction.nextToken());
System.out.println(denom);
}else{
StringTokenizer whiteSpace = new StringTokenizer(fraction, " ");
int num = Integer.parseInt(whiteSpace.nextToken());
System.out.println(num);
}
}}
Is there any way to use a variable inside a particular method outside of that method in another method?
Yes you can do that. You can declare a variable in a method, use it there and pass it to another method, where you might want to use it. Something like this
void test1() {
int var = 1;
System.out.println(var); // using it
test2(var); // calling other method and passing the value of var
}
void test2(int passedVarValue) {
System.out.println(passedVarValue); // using the passed value of the variable
// other stuffs
}
Related
I am trying to build a math Calculator in Java but I am having problems with it, I want to build it with methods and not just int.
I am having problems with how to print the return value (rishon+sheni) and also how to check if the in.nextLine() that the console wrote equal to plus like that:
package mehadash;
import java.util.Scanner;
public class lilmod {
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
String plus = null;
String minus = null;
String math;
int sum = 0;
System.out.println("What kind of math you want to do?");
math = in.nextLine();
if(math = plus)
{
System.out.println("Enter the two numbers you would like to check");
SumNumbers(in.nextInt(),in.nextInt());
System.out.println("The answer is :" +SumNumbers());
}
minusNumbers(in.nextInt(),in.nextInt());
}
public static int SumNumbers(int rishon , int sheni)
{
return rishon + sheni;
}
public static int minusNumbers(int rishon , int sheni)
{
return rishon - sheni;
}
}
You can always just define more variables.
int numberA = in.nextInt();
int numberB = in.nextInt();
int result = SumNumbers(numberA, numberB);
System.out.println("The result: " + result);
how to print the return value (rishon+sheni)
Try this way:
System.out.println("The answer is :" +SumNumbers(in.nextInt(),in.nextInt()));
instead of
SumNumbers(in.nextInt(),in.nextInt());
System.out.println("The answer is :" +SumNumbers());
also how to check if the in.nextLine(); that the console wrote equal
to plus
Try
if(math.equals("+"))
instead of
if(math = plus)
New to Java. The task is to Create a MathQuiz application that asks the user whether they would like a simple or difficult math quiz and the number of questions they would like to answer. The application then displays the questions, one at a time,prompting the user for the answer and confirming whether or not the answer is correct. The MathQuiz application should include separate methods for the simple and difficult math quiz.The simple() method should display addition problems. The difficult() method should display multiplication problems. Random numbers should be generated for the quiz questions. This is what I have so far:
import java.util.Scanner;
public class MathQuiz {
public static double simple() {
int randomNumber1 = (int)(20 * Math.random()) + 1;
int randomNumber2 = (int)(20 * Math.random()) + 1;
int randomNumberAdd = randomNumber1 + randomNumber2;
//user input
Scanner keyboard = new Scanner(System.in);
System.out.print(randomNumber1 + " + " + randomNumber2 + " = ");
int GuessRandomNumberAdd = keyboard.nextInt();
if (GuessRandomNumberAdd == randomNumber1 + randomNumber2) {
System.out.println("Correct!");
}else {
System.out.println("Wrong. The correct answer is " + randomNumberAdd);
}
}
public static double difficult() {
int randomNumber1 = (int)(20 * Math.random()) + 1;
int randomNumber2 = (int)(20 * Math.random()) + 1;
int randomNumberMul = randomNumber1 * randomNumber2;
int correct = 0;
//user input
Scanner keyboard = new Scanner(System.in);
System.out.print(randomNumber1 + " * " + randomNumber2 + " = ");
int GuessRandomNumberMul = keyboard.nextInt();
if (GuessRandomNumberMul == randomNumber1 * randomNumber2) {
System.out.println("Correct!");
}else{
System.out.println("Wrong. The correct answer is " + randomNumberMul);
}
}
//user options
public static void main(String[] args) {
int choice;
Scanner input = new Scanner(System.in);
System.out.println("There are two levels available:");
System.out.println("1. Simple");
System.out.println("2. Difficult");
System.out.print("Enter your choice: ");
choice = input.nextInt();
if (choice == 1) {
simple();
} else if (choice == 2) {
difficult();
}
input.close();
}
}
public static double simple() {}
public -> It specifies the access level of this function.
static -> It means this function is a behavior of your class and not specific to any instance of this class.
double -> It's what your function returns, a double typed value here, as an output at end of execution.
simple()-> It's your function name
In both of your functions simple() and difficult() you are not returning any value as output. So you have to change it to void.
Change your method simple() and difficult() return type from double to void and the error should go away
Change the return type of simple() and double() method to void, i.e.
public static void simple() and
public static void difficult()
The return type of these methods is currently double, so it is expected to return a double value. If they don't return a double value, the compiler will give you an error. So, if you don't plan to return a value in your methods, change the return type to void.
Removing the return type of double from your method's signature and setting it to void, the error should go away.
public static void simple() {
// your code
}
public static void difficult() {
// your code
}
For my school I need to create a method which moves a bug in any direction. I have the following code:
package Test;
//imports
import java.util.Scanner;
import java.util.Random;
public class test {
public static void main(String[] args) {
Scanner reader = new Scanner(System.in);
ABug[] BugObj = new ABug[4]; //Creating object BugObj of class ABug
int loop = 1;
int i = 0;
do {
BugObj[i] = new ABug(); //creating instance
System.out.println("Please enter the name of the bug:");
BugObj[i].name = reader.next();
System.out.println("Please enter the species of the bug:");
BugObj[i].species = reader.next();
System.out.println("Please enter the horizontal position of the bug:");
BugObj[i].horpos = reader.nextInt();
System.out.println("Please enter the vertical postion of the bug:");
BugObj[i].vertpos = reader.nextInt();
System.out.println("_______________ Bug " +(+i+1) + " _______________\n" );
System.out.println("Name: " + BugObj[i].name); //Printing bug information out
System.out.println("Species: " + BugObj[i].species);
System.out.println("Horizontal Position: " + BugObj[i].horpos);
System.out.println("Vertical Postion: " + BugObj[i].vertpos + "\n\n");
move();
i++;
System.out.println("Would you like to enter another bug? \n 0-No, 1-Yes\n");
loop = reader.nextInt();
} while(loop == 1);
}
public static void move() {
Scanner reader = new Scanner(System.in);
System.out.println("Would you like this bug to move?\n 0-No, 1-Yes\n");
if (reader.nextInt() == 0) {
System.exit(0);
}
int r = (int) (Math.random() * (2- -2)) + -2;
System.out.println(r);
}
}
class ABug { //ABug class
int horpos, vertpos, energy, id;
char symbol;
String species, name;
}
Basically all I need to do is use the values of the bugs position with the random number generated in the method. I am really new to java and am unsure how to do it or even if its possible.
Since objects are passed by reference in java, you can just pass your ABug object to the move function and change the horpos, vertpos attributes. so
move(BugObj[i]);
and
public static void move(ABug bug){
Scanner reader = new Scanner(System.in);
System.out.println("Would you like this bug to move?\n 0-No, 1-Yes\n");
if (reader.nextInt() == 0)
{
System.exit(0);
}
int r = (int) (Math.random() * (2- -2)) + -2;
int originalHorpos = bug.horpos
int originalVertpos = bug.vertpos
// Now just change the attributes however you see fit. i am just adding r
bug.horpos = originalHorpos + r;
bug.vertpos = originalVertpos + r
/*by the way, we dont need to use variables for the original values. something like this would also work
bug.horpos += r;
bug.vertpos += r;
i just want to explain that in java when you pass objects, they are passed by reference and hence you have access to all of its members.
*/
System.out.println(r);
}
also, you dont need to declare the Scanner object again inside the move function. you can pass that to the move function as well and then read as many times as you like.
I have made it a little further. It turns out I can use loops but not arrays in my assignment. So here's the current version (keep in mind no final calculations or anything yet.) So if you look at the homework method, you can see I am asking for the "number of assignments." Now, for each assignment, I need to ask for and sum both the Earned Score and the Maximum Possible Score. So for instance, if there were 3 assignments, they might have earned scores of 18, 22, and 29, and maximum possible scores of 20, 25, and 30 respectively. I need to grab both using the console, but I don't know how to get two variables using the same loop (or in the same method).
Thanks in advance for your help!
import java.util.*;
public class Grades {
public static void main(String[] args) {
welcomeScreen();
weightCalculator();
homework();
}
public static void welcomeScreen() {
System.out.println("This program accepts your homework scores and");
System.out.println("scores from two exams as input and computes");
System.out.println("your grade in the course.");
System.out.println();
}
public static void weightCalculator() {
System.out.println("Homework and Exam 1 weights? ");
Scanner console = new Scanner(System.in);
int a = console.nextInt();
int b = console.nextInt();
int c = 100 - a - b;
System.out.println();
System.out.println("Using weights of " + a + " " + b + " " + c);
}
public static void homework() {
Scanner console = new Scanner(System.in);
System.out.print("Number of assignments? ");
int totalAssignments = console.nextInt();
int sum = 0;
for (int i = 1; i <= totalAssignments; i++) {
System.out.print(" #" + i + "? ");
int next = console.nextInt();
sum += next;
}
System.out.println();
System.out.println("sum = " + sum);
}
}
I don't know where exactly your problem is, so I will try to give you some remarks. This is how I would start (of course there are other ways to implement this):
First of all - create Assignment class to hold all informations in nice, wrapped form:
public class Assignment {
private int pointsEarned;
private int pointsTotal;
public Assignment(int pointsEarned, int pointsTotal) {
this.pointsEarned = pointsEarned;
this.pointsTotal = pointsTotal;
}
...getters, setters...
}
To request number of assignments you can use simply nextInt() method and assign it to some variable:
Scanner sc = new Scanner(System.in);
int numberOfAssignments = sc.nextInt();
Then, use this variable to create some collection of assignments (for example using simple array):
Assignment[] assignments = new Assignment[numberOfAssignments];
Next, you can fill this collection using scanner again:
for(int i = 0; i < numberOfAssignments; i++) {
int pointsEarned = sc.nextInt();
int pointsTotal = sc.nextInt();
assignments[i] = new Assignment(pointsEarned, pointsTotal)
}
So here, you have filled collection of assignments. You can now print it, calculate average etc.
I hope above code gives you some remarks how to implement this.
I'm writing a program for my class where I have to use a for loop to takes two numbers from the keyboard. The program should then raise the first number to the power of the second number. Use a for loop to do the calculation. I'm getting the error that inum3 is not being initialized (I understand because the loop may never enter) but I cannot figure out how to make this work. Line 25 and 28 to be specific.
import javax.swing.*;
public class Loop2
{
public static void main(String[] args)
{
int inum1, inum2, inum3, count;
String str;
str = JOptionPane.showInputDialog("Please Enter a Numer");
inum1 = Integer.parseInt(str);
str = JOptionPane.showInputDialog("Please Enter a Numer");
inum2 = Integer.parseInt(str);
for (count = 1; count == inum2; count+=1)
{
inum3 = inum3 * inum1;
}
JOptionPane.showMessageDialog(null, String.format ("%s to the power of %s = %s", inum1,inum2, inum3), "The Odd numbers up to" + inum1,JOptionPane.INFORMATION_MESSAGE);
}//main
}// public
you need to initialize the variable inum3. As it stands right now, when your program tries to execute
inum3 = inum3 * inum1;
inum3 has no value, so it can't do the multiplication.
I think you want it to be 1 in this case.
So instead of
int inum1, inum2, inum3, count;
you can do
int inum1, inum2, inum3 = 1, count;
initialize num3 to one because you cand use something to define itself.
num3 = one;
import javax.swing.JOptionPane;
public class Loop2 {
public static void main(String[] args) {
int base, exp, result = 1;
String str;
str = JOptionPane.showInputDialog("Please Enter a Number");
base = Integer.parseInt(str);
str = JOptionPane.showInputDialog("Please Enter an Exponent");
exp = Integer.parseInt(str);
for (int count = 0; count < exp; count++) {
result *= base;
}
JOptionPane.showMessageDialog(null, String.format("%s to the power of %s = %s", base, exp, result),
"The Odd numbers up to" + base, JOptionPane.INFORMATION_MESSAGE);
}
}