Monthly Archives: November 2011

Code of the Day: Groovy Print all Methods of an object

Groovy Code

/**
* @function printAllMethods
* @purpose Prints an objects class name and then list the associated class functions.
*/
// Filename: printAllMethodsExample.groovy
void printAllMethods( obj ){
    if( !obj ){
		println( "Object is null\r\n" );
		return;
    }
	if( !obj.metaClass && obj.getClass() ){
        printAllMethods( obj.getClass() );
		return;
    }
	def str = "class ${obj.getClass().name} functions:\r\n";
	obj.metaClass.methods.name.unique().each{ 
		str += it+"(); "; 
	}
	println "${str}\r\n";
}

Example Code

// Filename: printAllMethodsExample.groovy
void printAllMethods( obj ){
    if( !obj ){
		println( "Object is null\r\n" );
		return;
    }
	if( !obj.metaClass && obj.getClass() ){
        printAllMethods( obj.getClass() );
		return;
    }
	def str = "class ${obj.getClass().name} functions:\r\n";
	obj.metaClass.methods.name.unique().each{ 
		str += it+"(); "; 
	}
	println "${str}\r\n";
}
printAllMethods( null );
printAllMethods( 1 );
printAllMethods( "string" );
printAllMethods( [1:1] );

Output

Object is null
 
class java.lang.Integer functions:
equals(); getClass(); hashCode(); notify(); notifyAll(); toString(); wait(); byteValue(); doubleValue(); floatValue(); intValue(); longValue(); shortValue(); bitCount(); compare(); compareTo(); decode(); getInteger(); highestOneBit(); lowestOneBit(); numberOfLeadingZeros(); numberOfTrailingZeros(); parseInt(); reverse(); reverseBytes(); rotateLeft(); rotateRight(); signum(); toBinaryString(); toHexString(); toOctalString(); valueOf(); 
 
class java.lang.String functions:
equals(); getClass(); hashCode(); notify(); notifyAll(); toString(); wait(); charAt(); codePointAt(); codePointBefore(); codePointCount(); compareTo(); compareToIgnoreCase(); concat(); contains(); contentEquals(); copyValueOf(); endsWith(); equalsIgnoreCase(); format(); getBytes(); getChars(); indexOf(); intern(); isEmpty(); lastIndexOf(); length(); matches(); offsetByCodePoints(); regionMatches(); replace(); replaceAll(); replaceFirst(); split(); startsWith(); subSequence(); substring(); toCharArray(); toLowerCase(); toUpperCase(); trim(); valueOf(); 
 
class java.lang.Class functions:
equals(); getClass(); hashCode(); notify(); notifyAll(); toString(); wait(); clear(); containsKey(); containsValue(); entrySet(); get(); isEmpty(); keySet(); put(); putAll(); remove(); size(); values(); clone();

Larry Battle

I love to program, and discover new tech. Check out my stackoverflow and github accounts.

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Video: Variables in Groovy

Larry Battle

I love to program, and discover new tech. Check out my stackoverflow and github accounts.

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Video: Metaprogramming in Groovy

Larry Battle

I love to program, and discover new tech. Check out my stackoverflow and github accounts.

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Improved Code for Javascript Decimal to Fraction

This post improves the code at “Code of the Day Javascript Decimal to fraction” by using Euclid’s Algorithm to find the Great Common Factor or GCF, aka GCD. This method provides a speed up of 10x when compared to the original algorithm posted.

Code

/**
*@function gcd (aka Euclid's algorithm)
*@purpose returns the greatest common factor between two numbers;
*/
function gcd(a, b) {
    return (b) ? gcd(b, a % b) : a;
}
/**
*@function dec2Frac
*@purpose returns a decimal as a fraction.
*/
var dec2Frac = function ( num ) {
	var top = num.toString().replace(/\d+[.]/, '');
	var bot = Math.pow(10, top.length);
	if (num > 1) {
		top = +top + Math.floor(num) * bot;
	}
	var x = gcd(top, bot);
	return (top / x) + "/" + (bot / x);
};

Usage

dec2Frac( 1.24325 ) // returns "4973/4000"
dec2Frac( 2.45 ) // returns "49/20"

Speed Test between Version 1 and 2 of dec2Frac()

//@requires Firebug or Chrome Developer Tools
//The following code test the speed difference between the Version 1 and 2 of dec2Frac.
function gcd(a, b) {
    return (b) ? gcd(b, a % b) : a;
}
var dec2FracV2 = function (d) {
	var top = d.toString().replace(/\d+[.]/, '');
	var bot = Math.pow(10, top.length);
	if (d > 1) {
		top = +top + Math.floor(d) * bot;
	}
	var x = gcd(top, bot);
	return (top / x) + "/" + (bot / x);
};
function dec2FracV1(d) {
    var df = 1, top = 1, bot = 1;
    var limit = 1e5; //Increase the limit to get more precision.
 
    while (df != d && limit-- > 0) {
        if (df < d) {
            top += 1;
        }
        else {
            bot += 1;
            top = parseInt(d * bot, 10);
        }
        df = top / bot;
    }
    return top + '/' + bot;
}
var getRandomNum = function (i, decLen) {
	return (Math.random() * (i || 1)).toFixed(decLen);
};
 
var runTest = function ( funcName ) {
	var func = { "V1": dec2FracV1, "V2": dec2FracV2 }[ funcName ];
	var i = 1000;
	while (i--) {
		num = getRandomNum(10, 4);
		var x = func(num);
		if (num != eval(x)) {
			console.warn("ERROR: Function %s, The fraction %s != %s", funcName, num, x);
		}
	}
};
console.time( 'V1' );
runTest( "V1" );
console.timeEnd( 'V1' );
 
console.time( 'V2' );
runTest( "V2" );
console.timeEnd( 'V2' );

Chrome Result:
V1: 11628ms
V2: 185ms

Try the test out yourself
jsbin.com

Larry Battle

I love to program, and discover new tech. Check out my stackoverflow and github accounts.

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