The method you want is [BigInteger#valueOf(long val)][1].

E.g.,

    BigInteger bi = BigInteger.valueOf(myInteger.intValue());

Making a String first is unnecessary and undesired.

  [1]: http://download.oracle.com/javase/6/docs/api/java/math/BigInteger.html#valueOf(long)

converting Integer to BigInteger

    		BigInteger big_integer = BigInteger.valueOf(1234);
converting BigInteger back to Integer

    int integer_value = big_integer.intValue();
converting BigInteger back to long

    long long_value = big_integer.longValue();
converting string to BigInteger

    		BigInteger bigInteger = new BigInteger(&quot;1234&quot;);
converting BigInteger back to string

    		String string_expression = bigInteger.toString();




You can do in this way:

        Integer i = 1;
        new BigInteger(&quot;&quot; + i);

The numpy docs recommend using array instead of matrix for working with matrices. However, unlike octave (which I was using till recently), * doesn&#39;t perform matrix multiplication, you need to use the function matrixmultipy(). I feel this makes the code very unreadable.

Does anybody share my views, and has found a solution?

how does multiplication differ for NumPy Matrix vs Array classes?

I have a matrix (32X48).

How can I convert the matrix into a single dimensional array?

Convert a matrix to a 1 dimensional array

I was wondering if there was any way to convert a variable of type Integer, to BigInteger. I tried typecasting the Integer variable, but i get an error that says inconvertible type.

Converting from Integer, to BigInteger

<p>I was wondering if there was any way to convert a variable of type Integer, to BigInteger. I tried typecasting the Integer variable, but i get an error that says inconvertible type.</p>


I have an android project that uses ant to build, is it possible to import this ant project in eclipse IDE?

 update : There is an option to create project using ant `build.xml` in eclipse File-&gt;New-&gt;Project-&gt;Java-&gt;Java project from existing ant Buildfile. and if the build.xml file is selected it show error `Specified buildfile does not contain a javac task`

I guess javac is declared in this task

    &lt;taskdef name=&quot;setup&quot;
    classname=&quot;com.android.ant.SetupTask&quot;
    classpathref=&quot;android.antlibs&quot;/&gt;



Importing ant build.xml in Eclipse

I&#39;ve gone through all the [documentation][1] of [logback][2] and I can&#39;t find anywhere the documentation to configure the encoder&#39;s pattern when logging, such as:

&lt;!-- language: xml --&gt;

    &lt;encoder&gt;
      &lt;pattern&gt;%d{HH:mm:ss.SSS} %-4relative %-5level %logger{35} - %msg%n&lt;/pattern&gt;
    &lt;/encoder&gt;

I would like a table (like the one that log4j has) explaining the different options to configure the pattern. 

Where is the documentation of the pattern? Maybe they are defined in another project?


  [1]: http://logback.qos.ch/documentation.html
  [2]: http://logback.qos.ch/

Where is logback encoder pattern documentation

Why does this throw `NullPointerException`

    public static void main(String[] args) throws Exception {
        Boolean b = true ? returnsNull() : false; // NPE on this line.
        System.out.println(b);
    }

    public static Boolean returnsNull() {
        return null;
    }
    
while this doesn&#39;t

    public static void main(String[] args) throws Exception {
        Boolean b = true ? null : false;
        System.out.println(b); // null
    }

?

The solution is by the way to replace `false` by `Boolean.FALSE` to avoid `null` being unboxed to `boolean` --which isn&#39;t possible. But that isn&#39;t the question. The question is *why*? Are there any references in JLS which confirms this behaviour, especially of the 2nd case?

Booleans, conditional operators and autoboxing

I&#39;m designing a new app based on JPA/Hibernate, Spring and Wicket. The distinction between the DAO and Service layers isn&#39;t that clear to me though. According to Wikipedia, DAO is 

&gt; an object that provides an abstract
&gt; interface to some type of database or
&gt; persistence mechanism, providing some
&gt; specific operations without exposing
&gt; details of the database.

I was wondering whether a DAO could contain methods that don&#39;t really have to do much with data access, but are way easier executed using a query? For example &quot;get a list of all airlines that operate on a certain set of airports&quot;? It sounds to me to be more of a service-layer method, but I&#39;m not sure if using JPA EntityManager in the service layer is an example of good practice?

DAO and Service layers (JPA/Hibernate + Spring)

Can anyone shed some light on why `Double.MIN_VALUE` is not actually the minimum value that Doubles can take? It is a positive value, and a Double can of course be negative.

I understand why it&#39;s a useful number, but it seems a very unintuitive name, especially when compared to `Integer.MIN_VALUE`. Calling it `Double.SMALLEST_POSITIVE` or `MIN_INCREMENT` or similar would have clearer semantics.

Also, what is the minimum value that Doubles can take? Is it `-Double.MAX_VALUE`? The docs don&#39;t seem to say.

Why is Double.MIN_VALUE in not negative

Is there a library that will find the square root of a BigInteger? I want it computed offline - only once, and not inside any loop. So even computationally expensive solution is okay.

I don&#39;t want to find some algorithm and implement. A readily available solution will be perfect.

How can I find the Square Root of a Java BigInteger?

I have been using int(10) and just noticed that Wordpress uses bigint(20) - What is different to use bigint(20) and int(10) for id auto increment? Which one should I use for id column?

    `id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,

Vs
    
    `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

Thanks.

MySQL: bigint Vs int

How would I go about doing arithmetic, + - / * % !,  with arbitrarily large integers without using `java.math.BigInteger`?

For instance, the factorial of 90 returns 0 in Java.
I would like to be able to solve that.

How to handle very large numbers in Java without using java.math.BigInteger

I&#39;m transferring raw data like `[{id: 12000000000002539, Name: &quot;Some Name&quot;}]` and I&#39;m getting the object `[{id: 12000000000002540, Name: &quot;Some Name&quot;}]` after parsing, for now server side converting id into string seems to help.
But is there a better way to transfer bigint data correctly?

JSON transfer of bigint: 12000000000002539 is converted to 12000000000002540?

I looked into this [stackoverflow question relating to Big Integer][1] and specifically I do not understand this line (the words in italics):

&gt; In the BigInteger class, *I have no limits* and there are some helpful
&gt; functions there but it is pretty depressing to convert your beautiful
&gt; code to work with the BigInteger class, specially when primitive
&gt; operators don&#39;t work there and you must use functions from this class.

I don&#39;t know what I am missing but to represent something that has no limit you would require infinite memory ? Whats is the trick here ?

[1]:https://stackoverflow.com/questions/2776400/biginteger-or-not-biginteger

Content Type	Original Author	Original Content on Stackoverflow
Question	Steffan Harris	View Question on Stackoverflow
Solution 1 - Java	jbindel	View Answer on Stackoverflow
Solution 2 - Java	Fabala Dibbasey	View Answer on Stackoverflow
Solution 3 - Java	Giorgios Karagounis	View Answer on Stackoverflow

Converting from Integer, to BigInteger

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Convert a matrix to a 1 dimensional array

how does multiplication differ for NumPy Matrix vs Array classes?

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