java - 帮助在 Java 代码中计算带分数

Question

我想计算1_1/2 * 1_1/2. 我不知道我们该怎么做，但下面是我当前的代码，下面是我对此实现的想法代码。我知道我的代码仅限于基本的 num1 操作。和 num2。我想如果 num1 或 num2 等于 1_1/2 是 1 似乎是一个整数并使其成为 2/2 并将其添加到 1/2 以使 3/2 并进行除法以使其成为 1.5 并遵循方程套装。

static int DO_DEBUG = 0;  // set to 1 for messages on, or 0 for messages off

static final boolean BASIC_VERSION = true;


public static void main( String[] args ) {

    calculator();
    //test();
}


public static void test() {
    String[] tests  = { 
            "1+1",
            "12 * 12",
            "1_1/2 * 1_1/2",
            "12 + mom",
            "12/3 / 3",
            "1_/3 + 5",
            "1 & 4",
            "12 +5",
            "1/3 - 1_4/5/6"
    };
    for (int i = 0; i < tests.length; i++ ) {
        System.out.println( "TESTING: " + tests[i] );
        processInput( tests[i] );
    }

}
static void calculator() {

    Scanner console = new Scanner ( System.in ); //turing input on

    System.out.println();
    String level = "Basic";
    if (! BASIC_VERSION ) {
        level = "Advanced";
    }
    System.out.println( "Welcome to the " + level + " Calculator");// have the option to pick basic or advance

    String input = "";
    while ( true ) {
        printPrompt();//this prompt is introduced in a different method
        input = console.nextLine();
        if ( isQuitRequest( input ) ) {//method to quit, says 'bye'
            break;//ends
        }
        processInput( input );// doing the task
    }
    System.out.println( "bye" );
    System.out.println( );
    console.close(); // quite keyword that closes console
}

static boolean isQuitRequest( String input ) {
    return input.equalsIgnoreCase( "quit" );
}

static void processInput( String input )  {

    if ( isQuitRequest( input ) ) { // if quit, does not reach here
        return;
    }

    String error = null;

    String[] tokens = input.split(" ");
    if ( tokens.length < 3 ) {
        error = "Not enough entires.";
    } else if (tokens.length > 3 ) {
        error = "Too many entries.";
    }
    if (error != null ) {
        printError( input, error );
        return;
    }

    String operator = tokens[1];
    String addition  = "+";
    String subtraction = "-";
    String multiplication = "*";
    String division = "/";
    double num1 = Double.parseDouble(tokens[0]);
    double num2 = Double.parseDouble(tokens[2]);
    double result;
    String number1 = tokens[0];
    String operation = tokens[1];
    String number2 = tokens[2];
    debug( "processInput: parse result number1='" + number1 + "' "
            + "number2='" + number2 + "' "
            + "operation='" + operation  + "'."
        );

    if ( (! isNumberValid( number1 ) ) 
            || (! isNumberValid( number2 )
            || ( operation.length() != 1 )
            || ("+-*/".indexOf( operation ) < 0 )) ) {
        error = "Syntax error.";
    }
        // If there is an error, print it,
        //  else print the parse results.
    if (error != null ) {
        printError( input, error );
    } else {
        //System.out.println( "Numbers are " + number1 + " and "
            //  + number2 + ".  Operation is " + operation +".");

        if (operator.equals(addition)){
            result = num1 + num2;
            System.out.println("Answer is " + result);          
        }
        else if (operator.equals(subtraction)){
            result = num1 - num2;
            System.out.println("Answer is " + result);          
        }
        else if (operator.equals(multiplication)){
            result = num1 * num2;
            System.out.println("Answer is " + result);          
        }
        else if (operator.equals(division)) {
            result = num1 / num2;
            System.out.println("Answer is " + result);          
        }
        else {

        }

            }
    }



//just validating -_-
 static boolean isNumberValid( String  numstr ) {
     boolean isValid = true;
     if ( BASIC_VERSION ) {
         isValid = isValidInt( numstr );
     } else {    // ADVANCED version.
         isValid =  isValidMixedFraction( numstr );;
     }
     return isValid;
 }

//This is to assure that everything entered is valid
 static boolean isValidInt( String  numstr ) {
     boolean isValid = true;
     for( int i = 0; i < numstr.length(); i++ ) {
        char c = numstr.charAt( i );
        if (! Character.isDigit( c )) {
            isValid = false;
        }
     }
     return isValid;
 }


 // formating of mixed numbers
 static boolean isValidMixedFraction( String  numstr ) {
     boolean isvalid = true;

        // get parts this string around the _
     String[] underscoreTokens = numstr.split("_");
     String firstPart = underscoreTokens[0];
     String secondPart;
     if( underscoreTokens.length == 1 ) {
         secondPart = null;
     } else  if( underscoreTokens.length == 2 ) {
         secondPart =  underscoreTokens[1];
     } else {  // underscoreTokens.length > 2 length matters
         return false;
     }


     debug( "isValidMixedFraction:  firstPart='"+ firstPart + "',  secondPart='"
             + secondPart +"'" );        
     if (secondPart == null ) {
         // first part can be "n" or "n/n"
         if( (! isValidInt( firstPart ) ) && (! isValidFraction( firstPart )) ) {
             isvalid = false;
         }
     } else {  // 2nd part not null.

         if  ( ! isValidInt( firstPart ) ) {
             isvalid = false;
         }
         if  ( ! isValidFraction( secondPart ) ) {
             isvalid = false;
         }
     }   // end else second part not null
     return isvalid;
 }

//validating the format of the fraction if it is to be valid
 static boolean isValidFraction( String  numstr ) {
     boolean isValid = true;
        // get parts this string around the _
     String[] slashTokens = numstr.split("/");
     if( slashTokens.length != 2 ) {
        return false;
     }

     String firstPart = slashTokens[0];
     String secondPart = slashTokens[1];

     if ( ! isValidInt(firstPart) ) {
         isValid = false;
     }  else if (! isValidInt(secondPart) ) {
         isValid = false;
     }
     return isValid;
 }


 static void printError( String input, String error ) {
    System.out.println( "ERROR: " + error + "  for input '" + input + "'." );
}

static void printPrompt() {
    System.out.print( "> " );
}

static void debug( String s ) {
    if ( 0 < DO_DEBUG) {
        System.out.println( "DBG: " + s);}
    }

}

其他：

String num1; 
String num2;

d1 = Double.parse.Double(num 1);
d1 = convtMixed(num1);



double convertMixed(String fract)
double result = 0;
fract.split(_);

result + = Double.parseDouble(token[0]);

如何？你会怎么做？我使用范围对吗？在哪里？

score 0 · Accepted Answer

我真的希望你在解析方程时不需要帮助，只是为了让整个事情顺利进行。如果是真的，您可能会发现我的回答很有用。

尝试为数字创建新类。这个新类将有两个字段：

int divisor
int divident

整数也可以这样保存：1 = 1/1, 2=2/1。

您将必须提供标准化功能，将 25/5 更改为 5/1 的功能。这相对容易，因为您只需找到这些数字的最大公约数，然后将它们相除。

您将不得不覆盖加法、乘法、除法等操作。例如（加法的伪代码）

Number a;
Number b;
divident = a.divident * b.divident;
divisor = a.divisor * b.divident + b.divisor*a.divident;
normalise();

在并且如果您只想要原始结果，您可以实现将简单地划分除数和除数并将结果作为双精度返回的函数

例如： 1_1/2 使用该方法将被处理如下（解析后）： number a: 1/1 number b: 1/2 action: 加法如果加法执行正确，将返回 3/2 作为结果。

在您的应用程序模型中，我不建议将 3/2 更改为 1.5 。这种或多或少的一种方式转换应该在应用程序的 wiev 部分完成。这样，您可以灵活地显示结果。您可以以用户想要的任何方式提供它，就像在真正的高级计算器中一样。

score 0 · Accepted Answer

从这段代码中得到想法，您的代码是错误的先生，您将面临很多麻烦，所以我建议您更改整个代码

*不要使用很多 if ，用 switch 替换它

String number1 = tokens[0];
String operation = tokens[1];
String number2 = tokens[2];

if(number2 == '('){
tempNum = number1 ;
tempOP =operation ;

number1 =  tokens[2];
operation = tokens[3];
number2 = tokens[4];
     }

if( tokens[5] == ')'){
number1 = tempNum ;
operation = tempOP ;
number2 = result 

}

我的建议以改进您的代码

    String addition  = "+";
    String subtraction = "-";
    String multiplication = "*";
    String division = "/";



 if (operator.equals(addition)){
            result = num1 + num2;
            System.out.println("Answer is " + result);          
        }
        else if (operator.equals(subtraction)){
            result = num1 - num2;
            System.out.println("Answer is " + result);          
        }
        else if (operator.equals(multiplication)){
            result = num1 * num2;
            System.out.println("Answer is " + result);          
        }
        else if (operator.equals(division)) {
            result = num1 / num2;
            System.out.println("Answer is " + result);          
        }

用 , 替换所有这些代码（如果你有很多比较，不要使用嵌套 if，使用 switch）

  switch (operator) {
    case "+":
         result = num1 + num2;
         System.out.println("Answer is " + result); 
    break;
// other compare here
    default:
        break;
    }


 String[] tokens = input.split(" ");
    if ( tokens.length < 3 ) {
        error = "Not enough entires.";
    } else if (tokens.length > 3 ) {
        error = "Too many entries.";
    }

在这里你限制你的操作只有三个元素，使用StringTokenizer

                                              // any input here
StringTokenizer string = new StringTokenizer("1 / ( 1 / 2 )");
       for(int i = 0 ; i<string.countTokens() ; i++){
           // you can put result in array of string to refer to it alter 
           //String [] result , and fill it with tokens from StringTokenizer 
           String result = string.nextToken();
           if(result.equalsIgnoreCase("(")){
               // write my syntax here 

           }
       }

java - **帮助** 在 Java 代码中计算带分数

2 回答 2

Related

Reference

java - 帮助在 Java 代码中计算带分数