我是

Java编程的新手,我的AP计算机编程课程已经完成,所以请耐心等待.我必须弄清楚如何将两个分数相乘.我想知道是否有任何方法在方法中声明一个变量并在该方法之外使用它(在intro方法中我的while循环).谢谢,希望不要混淆！

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);

}

}}