We Keep Coding

Converting from base X to base Y in JAVA is returning different characters than the same function in PHP

I've created a method in JAVA in order to do the same thing of an existing PHP function, that is: convert an arbitrarily large number from any base to any base.
The java method is working fine and I can convert numbers from one base to another and then convert it back, but the resulted strings are different from the PHP function. This is a problem to me, because I want to convert a number in PHP and then convert it back in JAVA.
For example, lets convert the number 998765;43210;9999;2 from Base11 with alphabet 0123456789; to Base21 with alphabet 0123456789ABCDEFGHIJK in PHP and JAVA:
Result of the example in PHP:
convBase("998765;43210;9999;2", "0123456789;", "0123456789ABCDEFGHIJK") = "GJK7K6B2KKGKK96"
Result of the example in JAVA:
convBase("998765;43210;9999;2", "0123456789;", "0123456789ABCDEFGHIJK") = "1B0EJAJ0IG3DABI"
I would like the results to be the same, so I could convert a number in PHP and convert it back in JAVA.
I think that the problem can be character encoding, but I don't know how to solve it.
PHP function and test:
<?php
function convBase($numberInput, $fromBaseInput, $toBaseInput)
{
if ($fromBaseInput==$toBaseInput) return $numberInput;
$fromBase = str_split($fromBaseInput,1);
$toBase = str_split($toBaseInput,1);
$number = str_split($numberInput,1);
$fromLen=strlen($fromBaseInput);
$toLen=strlen($toBaseInput);
$numberLen=strlen($numberInput);
$retval='';
if ($toBaseInput == '0123456789')
{
$retval=0;
for ($i = 1;$i <= $numberLen; $i++)
$retval = bcadd($retval, bcmul(array_search($number[$i-1], $fromBase),bcpow($fromLen,$numberLen-$i)));
return $retval;
}
if ($fromBaseInput != '0123456789')
$base10=convBase($numberInput, $fromBaseInput, '0123456789');
else
$base10 = $numberInput;
if ($base10<strlen($toBaseInput))
return $toBase[$base10];
while($base10 != '0')
{
$retval = $toBase[bcmod($base10,$toLen)].$retval;
$base10 = bcdiv($base10,$toLen,0);
}
return $retval;
}
header('Content-Type: text/html; charset=utf-8');
$number = "998765;43210;9999;2";
$fromBase = "0123456789;";
$toBase = "0123456789ABCDEFGHIJK";
$converted = convBase($number, $fromBase, $toBase);
$back = convBase($converted, $toBase, $fromBase);
echo "Number: ".$number."<br>";
echo "Converted: ".$converted."<br>";
echo "Back: ".$back."<br>";
?>
JAVA method and test:
import java.math.BigInteger;
public class ConvBase{
public static String convBase(String number, String fromBaseInput, String toBaseInput){
if (fromBaseInput.equals(toBaseInput))
return number;
BigInteger fromLen = new BigInteger(""+fromBaseInput.length());
BigInteger toLen = new BigInteger(""+toBaseInput.length());
BigInteger numberLen = new BigInteger(""+number.length());
if(toBaseInput.equals("0123456789")){
BigInteger retval = BigInteger.ZERO;
for(int i=1; i<=number.length(); i++){
retval = retval.add(
new BigInteger(""+fromBaseInput.indexOf(number.charAt(i-1))).multiply(
fromLen.pow(numberLen.subtract(new BigInteger(""+i)).intValue())
//pow(fromLen, numberLen.subtract(new BigInteger(""+i)))
)
);
}
return ""+retval;
}
String base10 = fromBaseInput.equals("0123456789") ? number : convBase(number, fromBaseInput, "0123456789");
if(new BigInteger(base10).compareTo(toLen) < 0)
return ""+toBaseInput.charAt(Integer.parseInt(base10));
String retVal = "";
BigInteger base10bigInt = new BigInteger(base10);
while(!base10bigInt.equals(BigInteger.ZERO)){
retVal = toBaseInput.charAt(base10bigInt.mod(toLen).intValue()) + retVal;
base10bigInt = base10bigInt.divide(toLen);
}
return ""+retVal;
}
public static void main(String[] args) {
String number = "98765;43210;9999;2";
String fromBase = "0123456789;";
String toBase = "0123456789ABCDEFGHIJK";
String converted = ConvBase.convBase(number, fromBase, toBase);
String back = ConvBase.convBase(converted, toBase, fromBase);
System.out.println("Number = "+number);
System.out.println("Converted = "+converted);
System.out.println("Back = "+back);
System.exit(0);
}
}

There is a typo in your test case. Both programs seem to be correct, or at least consistent.
Your Java variant converts "98765;43210;9999;2" while your PHP program converts "998765;43210;9999;2". Note the two nines at the beginning. When I changed the number I got the following output:
Number = 998765;43210;9999;2
Converted = GJK7K6B2KKGKK96
Back = 998765;43210;9999;2
which is consistent with the output of the PHP version.

String converting issure

ive got a problem with string conversion.
I am trying to implement a system where numbers (BigDecimal) are printed to the screen when they are updated.
Therefore i created a subclass of BigDecimal (dpzahl) to detect the updated number and send a updaterequest to the ui.
So basically: i save the string (text) from String.xml. example:
"value of %s: %s"
and i save the references of the arguments in argument.
these references can be Strings, SpannableStrings or dpzahl's.
But while preparing the string.format ive got a problem:
Log.d(MainActivity.LOGTAG,"update request is executed");
final Object[] ARGS = new CharSequence[argumente.size()]; //to be put into the formater
int i = 0;
for(Object ooo: arguments) { // private ArrayList<Object> arguments; is a class variable
if (ooo instanceof dpzahl) { // dpzahl extends BigDecimal to get the number i want to format
ARGS[i] = haupt.format_bigies(((dpzahl) ooo).get()); //get the formated string
Log.d(MainActivity.LOGTAG,"number print:"+ARGS[i].toString());
}if(ooo instanceof SpannableString){ //some other arguments i may need in the string.format argument list
ARGS[i] = ((SpannableString)ooo);
}else{ //for any other object, mostly Strings
ARGS[i] = ooo.toString();
}
if (ooo instanceof dpzahl) { //only for debugprint
Log.d(MainActivity.LOGTAG,"loopvalue dpzahl:"+ARGS[i].toString());
}
Log.d(MainActivity.LOGTAG,"loopvalue:"+ARGS[i].toString());
i++;
}
for(Object ooo: ARGS) { //only for debugprint
if(ooo instanceof String){
Log.d(MainActivity.LOGTAG, "againarg Stirng:" + ((String)ooo));
}else if(ooo instanceof SpannableString) {
Log.d(MainActivity.LOGTAG, "againarg SpannableString:" + ((SpannableString)ooo).toString());
}
Log.d(MainActivity.LOGTAG, "againarg Object:" + ooo.toString());
}
sicht.post(new Runnable() {
#Override
public void run() {
Log.d(MainActivity.LOGTAG,"allargs:"+ Arrays.toString(ARGS));
view.setText(SpanFormatter.format(text, ARGS));//Copyright © 2014 George T. Steel, replace string.format for SpannableString
view.invalidate();//the linked TextView
}
});
If i put in the SpannableString "testvalue" and the BigDecimal expression for 4 the output is
output:
update request is executed
loopvalue:testvalue
formated BigDecimal:4
number print:4
loopvalue dpzahl:4.000000000
loopvalue:4.000000000
againarg SpannableString:testvalue
againarg Object:testvalue
againarg Stirng:4.000000000
againarg Object:4.000000000
allargs:[testvalue , 4.000000000]
so the TextView String should be "value of testvalue: 4" but it is "value of testvalue: 4.000000000"
So why have the Value of ARGS[1] first the value of String "4" and later the value "4.000000000" before it is passed to the formater?
ps: the problem appears when i implemented the SpannableString to the formater, before this, the line
final Object[] ARGS = new CharSequence[argumente.size()];
was
final Object[] ARGS = new String[argumente.size()];
and all work fine. But SpannableString does not extend Strings so i need the next upper lowest common denominator which is CharSequence.
pp: using
final Object[] ARGS = new Object[argumente.size()];
does not help.

Change
if(ooo instanceof SpannableString)
to
else if(ooo instanceof SpannableString)

How to validate JSON having multiple root elements

I am having a ccode, which bulids jsonfile in the below format.
{"swap":1,"si":11},{"system":1,host:"new"},{"Cpu":1}
If I validate this jsonfile data i get an error as:
Parse error on line 4:
...": 1, "si": 11},{ "system": 1,
---------------------^ Expecting 'EOF'
How to resolve this issue?

Wrap those jsonObjects in to an JsonArray while building. Then in java iterate through the jsonarray.

In jsonevery key is double quoted "key". Your jsonis missing double quotes at host key. Make sure you're writing a well-formed json.
{ "system": 1, "host": "new" }
^ ^

am not a expert in JSON but i think you want to change a JSON like array value
[{"swap":1,"si":11},{"system":1,host:"new"},{"Cpu":1}]
insted of
{"swap":1,"si":11},{"system":1,host:"new"},{"Cpu":1}

You can also use this custom function even if you have complex objects.
static getParsedJson(jsonString) {
const parsedJsonArr = [];
let tempStr = '';
let isObjStartFound = false;
for (let i = 0; i < jsonString.length; i += 1) {
if (isObjStartFound) {
tempStr += jsonString[i];
if (jsonString[i] === '}') {
try {
const obj = JSON.parse(tempStr);
parsedJsonArr.push(obj);
tempStr = '';
isObjStartFound = false;
} catch (err) {
// console.log("not a valid JSON object");
}
}
}
if (!isObjStartFound && jsonString[i] === '{') {
tempStr += jsonString[i];
isObjStartFound = true;
}
}
return parsedJsonArr;
}

Java: Get last element after split

I am using the String split method and I want to have the last element.
The size of the Array can change.
Example:
String one = "Düsseldorf - Zentrum - Günnewig Uebachs"
String two = "Düsseldorf - Madison"
I want to split the above Strings and get the last item:
lastone = one.split("-")[here the last item] // <- how?
lasttwo = two.split("-")[here the last item] // <- how?
I don't know the sizes of the arrays at runtime :(

You could use lastIndexOf() method on String
String last = string.substring(string.lastIndexOf('-') + 1);

Save the array in a local variable and use the array's length field to find its length. Subtract one to account for it being 0-based:
String[] bits = one.split("-");
String lastOne = bits[bits.length-1];
Caveat emptor: if the original string is composed of only the separator, for example "-" or "---", bits.length will be 0 and this will throw an ArrayIndexOutOfBoundsException. Example: https://onlinegdb.com/r1M-TJkZ8

You can use the StringUtils class in Apache Commons:
StringUtils.substringAfterLast(one, "-");

using a simple, yet generic, helper method like this:
public static <T> T last(T[] array) {
return array[array.length - 1];
}
you can rewrite:
lastone = one.split("-")[..];
as:
lastone = last(one.split("-"));

String str = "www.anywebsite.com/folder/subfolder/directory";
int index = str.lastIndexOf('/');
String lastString = str.substring(index +1);
Now lastString has the value "directory"

Gathered all possible ways together!!
By using lastIndexOf() & substring() methods of Java.lang.String
// int firstIndex = str.indexOf( separator );
int lastIndexOf = str.lastIndexOf( separator );
String begningPortion = str.substring( 0, lastIndexOf );
String endPortion = str.substring( lastIndexOf + 1 );
System.out.println("First Portion : " + begningPortion );
System.out.println("Last Portion : " + endPortion );
split()Java SE 1.4. Splits the provided text into an array.
String[] split = str.split( Pattern.quote( separator ) );
String lastOne = split[split.length-1];
System.out.println("Split Array : "+ lastOne);
How to split String before first comma?
Java 8 sequential ordered stream from an array.
String firstItem = Stream.of( split )
.reduce( (first,last) -> first ).get();
String lastItem = Stream.of( split )
.reduce( (first,last) -> last ).get();
System.out.println("First Item : "+ firstItem);
System.out.println("Last Item : "+ lastItem);
Apache Commons Langjar « org.apache.commons.lang3.StringUtils
String afterLast = StringUtils.substringAfterLast(str, separator);
System.out.println("StringUtils AfterLast : "+ afterLast);
String beforeLast = StringUtils.substringBeforeLast(str, separator);
System.out.println("StringUtils BeforeLast : "+ beforeLast);
String open = "[", close = "]";
String[] groups = StringUtils.substringsBetween("Yash[777]Sam[7]", open, close);
System.out.println("String that is nested in between two Strings "+ groups[0]);
Guava: Google Core Libraries for Java. « com.google.common.base.Splitter
Splitter splitter = Splitter.on( separator ).trimResults();
Iterable<String> iterable = splitter.split( str );
String first_Iterable = Iterables.getFirst(iterable, "");
String last_Iterable = Iterables.getLast( iterable );
System.out.println(" Guava FirstElement : "+ first_Iterable);
System.out.println(" Guava LastElement : "+ last_Iterable);
Scripting for the Java Platform « Run Javascript on the JVM with Rhino/Nashorn
Rhino « Rhino is an open-source implementation of JavaScript written entirely in Java. It is typically embedded into Java applications to provide scripting to end users. It is embedded in J2SE 6 as the default Java scripting engine.
Nashorn is a JavaScript engine developed in the Java programming language by Oracle. It is based on the Da Vinci Machine and has been released with Java 8.
Java Scripting Programmer's Guide
public class SplitOperations {
public static void main(String[] args) {
String str = "my.file.png.jpeg", separator = ".";
javascript_Split(str, separator);
}
public static void javascript_Split( String str, String separator ) {
ScriptEngineManager manager = new ScriptEngineManager();
ScriptEngine engine = manager.getEngineByName("JavaScript");
// Script Variables « expose java objects as variable to script.
engine.put("strJS", str);
// JavaScript code from file
File file = new File("E:/StringSplit.js");
// expose File object as variable to script
engine.put("file", file);
try {
engine.eval("print('Script Variables « expose java objects as variable to script.', strJS)");
// javax.script.Invocable is an optional interface.
Invocable inv = (Invocable) engine;
// JavaScript code in a String
String functions = "function functionName( functionParam ) { print('Hello, ' + functionParam); }";
engine.eval(functions);
// invoke the global function named "functionName"
inv.invokeFunction("functionName", "function Param value!!" );
// evaluate a script string. The script accesses "file" variable and calls method on it
engine.eval("print(file.getAbsolutePath())");
// evaluate JavaScript code from given file - specified by first argument
engine.eval( new java.io.FileReader( file ) );
String[] typedArray = (String[]) inv.invokeFunction("splitasJavaArray", str );
System.out.println("File : Function returns an array : "+ typedArray[1] );
ScriptObjectMirror scriptObject = (ScriptObjectMirror) inv.invokeFunction("splitasJavaScriptArray", str, separator );
System.out.println("File : Function return script obj : "+ convert( scriptObject ) );
Object eval = engine.eval("(function() {return ['a', 'b'];})()");
Object result = convert(eval);
System.out.println("Result: {}"+ result);
// JavaScript code in a String. This code defines a script object 'obj' with one method called 'hello'.
String objectFunction = "var obj = new Object(); obj.hello = function(name) { print('Hello, ' + name); }";
engine.eval(objectFunction);
// get script object on which we want to call the method
Object object = engine.get("obj");
inv.invokeMethod(object, "hello", "Yash !!" );
Object fileObjectFunction = engine.get("objfile");
inv.invokeMethod(fileObjectFunction, "hello", "Yashwanth !!" );
} catch (ScriptException e) {
e.printStackTrace();
} catch (NoSuchMethodException e) {
e.printStackTrace();
} catch (FileNotFoundException e) {
e.printStackTrace();
}
}
public static Object convert(final Object obj) {
System.out.println("\tJAVASCRIPT OBJECT: {}"+ obj.getClass());
if (obj instanceof Bindings) {
try {
final Class<?> cls = Class.forName("jdk.nashorn.api.scripting.ScriptObjectMirror");
System.out.println("\tNashorn detected");
if (cls.isAssignableFrom(obj.getClass())) {
final Method isArray = cls.getMethod("isArray");
final Object result = isArray.invoke(obj);
if (result != null && result.equals(true)) {
final Method values = cls.getMethod("values");
final Object vals = values.invoke(obj);
System.err.println( vals );
if (vals instanceof Collection<?>) {
final Collection<?> coll = (Collection<?>) vals;
Object[] array = coll.toArray(new Object[0]);
return array;
}
}
}
} catch (ClassNotFoundException | NoSuchMethodException | SecurityException
| IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
}
}
if (obj instanceof List<?>) {
final List<?> list = (List<?>) obj;
Object[] array = list.toArray(new Object[0]);
return array;
}
return obj;
}
}
JavaScript file « StringSplit.js
// var str = 'angular.1.5.6.js', separator = ".";
function splitasJavaArray( str ) {
var result = str.replace(/\.([^.]+)$/, ':$1').split(':');
print('Regex Split : ', result);
var JavaArray = Java.to(result, "java.lang.String[]");
return JavaArray;
// return result;
}
function splitasJavaScriptArray( str, separator) {
var arr = str.split( separator ); // Split the string using dot as separator
var lastVal = arr.pop(); // remove from the end
var firstVal = arr.shift(); // remove from the front
var middleVal = arr.join( separator ); // Re-join the remaining substrings
var mainArr = new Array();
mainArr.push( firstVal ); // add to the end
mainArr.push( middleVal );
mainArr.push( lastVal );
return mainArr;
}
var objfile = new Object();
objfile.hello = function(name) { print('File : Hello, ' + name); }
JavaScript Array constructor or array literal.

With Guava:
final Splitter splitter = Splitter.on("-").trimResults();
assertEquals("Günnewig Uebachs", Iterables.getLast(splitter.split(one)));
assertEquals("Madison", Iterables.getLast(splitter.split(two)));
Splitter, Iterables

Since he was asking to do it all in the same line using split so i suggest this:
lastone = one.split("-")[(one.split("-")).length -1]
I always avoid defining new variables as far as I can, and I find it a very good practice

You mean you don't know the sizes of the arrays at compile-time? At run-time they could be found by the value of lastone.length and lastwo.length .

Also you can use java.util.ArrayDeque
String last = new ArrayDeque<>(Arrays.asList("1-2".split("-"))).getLast();

In java 8
String lastItem = Stream.of(str.split("-")).reduce((first,last)->last).get();

I guess you want to do this in i line. It is possible (a bit of juggling though =^)
new StringBuilder(new StringBuilder("Düsseldorf - Zentrum - Günnewig Uebachs").reverse().toString().split(" - ")[0]).reverse()
tadaa, one line -> the result you want (if you split on " - " (space minus space) instead of only "-" (minus) you will loose the annoying space before the partition too =^) so "Günnewig Uebachs" instead of " Günnewig Uebachs" (with a space as first character)
Nice extra -> no need for extra JAR files in the lib folder so you can keep your application light weight.

Java toString() using reflection?

I was writing a toString() for a class in Java the other day by manually writing out each element of the class to a String and it occurred to me that using reflection it might be possible to create a generic toString() method that could work on ALL classes. I.E. it would figure out the field names and values and send them out to a String.
Getting the field names is fairly simple, here is what a co-worker came up with:
public static List initFieldArray(String className) throws ClassNotFoundException {
Class c = Class.forName(className);
Field field[] = c.getFields();
List<String> classFields = new ArrayList(field.length);
for (int i = 0; i < field.length; i++) {
String cf = field[i].toString();
classFields.add(cf.substring(cf.lastIndexOf(".") + 1));
}
return classFields;
}
Using a factory I could reduce the performance overhead by storing the fields once, the first time the toString() is called. However finding the values could be a lot more expensive.
Due to the performance of reflection this may be more hypothetical then practical. But I am interested in the idea of reflection and how I can use it to improve my everyday programming.

Apache commons-lang ReflectionToStringBuilder does this for you.
import org.apache.commons.lang3.builder.ReflectionToStringBuilder
// your code goes here
public String toString() {
return ReflectionToStringBuilder.toString(this);
}

Another option, if you are ok with JSON, is Google's GSON library.
public String toString() {
return new GsonBuilder().setPrettyPrinting().create().toJson(this);
}
It's going to do the reflection for you. This produces a nice, easy to read JSON file. Easy-to-read being relative, non tech folks might find the JSON intimidating.
You could make the GSONBuilder a member variable too, if you don't want to new it up every time.
If you have data that can't be printed (like a stream) or data you just don't want to print, you can just add #Expose tags to the attributes you want to print and then use the following line.
new GsonBuilder()
.setPrettyPrinting()
.excludeFieldsWithoutExposeAnnotation()
.create()
.toJson(this);

W/reflection, as I hadn't been aware of the apache library:
(be aware that if you do this you'll probably need to deal with subobjects and make sure they print properly - in particular, arrays won't show you anything useful)
#Override
public String toString()
{
StringBuilder b = new StringBuilder("[");
for (Field f : getClass().getFields())
{
if (!isStaticField(f))
{
try
{
b.append(f.getName() + "=" + f.get(this) + " ");
} catch (IllegalAccessException e)
{
// pass, don't print
}
}
}
b.append(']');
return b.toString();
}
private boolean isStaticField(Field f)
{
return Modifier.isStatic(f.getModifiers());
}

If you're using Eclipse, you may also have a look at JUtils toString generator, which does it statically (generating the method in your source code).

You can use already implemented libraries, as ReflectionToStringBuilder from Apache commons-lang. As was mentioned.
Or write smt similar by yourself with reflection API.
Here is some example:
class UniversalAnalyzer {
private ArrayList<Object> visited = new ArrayList<Object>();
/**
* Converts an object to a string representation that lists all fields.
* #param obj an object
* #return a string with the object's class name and all field names and
* values
*/
public String toString(Object obj) {
if (obj == null) return "null";
if (visited.contains(obj)) return "...";
visited.add(obj);
Class cl = obj.getClass();
if (cl == String.class) return (String) obj;
if (cl.isArray()) {
String r = cl.getComponentType() + "[]{";
for (int i = 0; i < Array.getLength(obj); i++) {
if (i > 0) r += ",";
Object val = Array.get(obj, i);
if (cl.getComponentType().isPrimitive()) r += val;
else r += toString(val);
}
return r + "}";
}
String r = cl.getName();
// inspect the fields of this class and all superclasses
do {
r += "[";
Field[] fields = cl.getDeclaredFields();
AccessibleObject.setAccessible(fields, true);
// get the names and values of all fields
for (Field f : fields) {
if (!Modifier.isStatic(f.getModifiers())) {
if (!r.endsWith("[")) r += ",";
r += f.getName() + "=";
try {
Class t = f.getType();
Object val = f.get(obj);
if (t.isPrimitive()) r += val;
else r += toString(val);
} catch (Exception e) {
e.printStackTrace();
}
}
}
r += "]";
cl = cl.getSuperclass();
} while (cl != null);
return r;
}
}

Not reflection, but I had a look at generating the toString method (along with equals/hashCode) as a post-compilation step using bytecode manipulation. Results were mixed.

Here is the Netbeans equivalent to Olivier's answer; smart-codegen plugin for Netbeans.