    BigDecimal value = new BigDecimal(Float.toString(123.4f));

From the [javadocs][1], the string constructor is generally the preferred way to convert a `float` into a BigDecimal, as it doesn&#39;t suffer from the unpredictability of the `BigDecimal(double)` constructor. 

[1]: http://download.oracle.com/javase/1.4.2/docs/api/java/math/BigDecimal.html

Quote from the docs:

&gt; *Note: For values other float and double  NaN and &#177;Infinity, this constructor is compatible with the values returned by Float.toString(float) and Double.toString(double). **This is generally the preferred way to convert a float or double into a BigDecimal**, as it doesn&#39;t suffer from the unpredictability of the BigDecimal(double) constructor.* 

    float f = 45.6f;
    BigDecimal bd = BigDecimal.valueOf(f);

Quote from documentations:

&gt; Note: This is generally the preferred way to convert a double (or
&gt; float) into a BigDecimal, as the value returned is equal to that
&gt; resulting from constructing a BigDecimal from the result of using
&gt; Double.toString(double).

Reference: [BigDecimal (Java Platform SE 6)][1]


  [1]: http://docs.oracle.com/javase/6/docs/api/java/math/BigDecimal.html#valueOf%28double%29

For a precision of 3 digits after the decimal point:

    BigDecimal value = new BigDecimal(f,
            new MathContext(3, RoundingMode.HALF_EVEN));



This is upto my knowledge :


       public static BigDecimal floatToBigDecimal(Float a){
		
		
		if(a == null || a.isInfinite() || a.isNaN()){
			return BigDecimal.ZERO;
		}
		try{
			return BigDecimal.valueOf(a);
			
		}catch(Exception e){
			return BigDecimal.ZERO;
		}
		
	}

&gt; *Note:This is generally the preferred way to convert a double (or float) into a BigDecimal, as the value returned is equal to that resulting from constructing a BigDecimal from the result of using Double.toString(double).


public static BigDecimal valueOf(double val)

 
**Parameters**:&lt;br&gt;
    val - double to convert to a BigDecimal.&lt;br&gt;
**Returns**:&lt;br&gt;
    a BigDecimal whose value is equal to or approximately equal to the value of val.&lt;br&gt;
**Throws:**&lt;br&gt;
    ***NumberFormatException*** - if val is infinite or NaN.&lt;br&gt;
**Since:**&lt;br&gt;
    1.5 &lt;br&gt;


I have checked whether Infinite or Not a Number, so that there is less chances of NumberFormatException

I&#39;ve been doing some reading on the Strategy Pattern, and have a question.  I have implemented a very basic Console Application below to explain what I&#39;m asking.

I have read that having &#39;switch&#39; statements is a red flag when implementing the strategy pattern.  However, I can&#39;t seem to get away from having a switch statement in this example.  Am I missing something?  I was able to remove the logic from the **Pencil**, but my **Main** has a switch statement in it now.  I understand that I could easily create a new **TriangleDrawer** class, and wouldn&#39;t have to open the **Pencil** class, which is good.  However, I would need to open **Main** so that it would know which type of **IDrawer** to pass to the **Pencil**.  Is this just what needs to be done if I&#39;m relying on the user for input?  If there&#39;s a way to do this without the switch statement, I&#39;d love to see it!

    class Program
    {
        public class Pencil
        {
            private IDraw drawer;

            public Pencil(IDraw iDrawer)
            {
                drawer = iDrawer;
            }

            public void Draw()
            {
                drawer.Draw();
            }
        }

        public interface IDraw
        {
            void Draw();
        }

        public class CircleDrawer : IDraw
        {
            public void Draw()
            {
                Console.Write(&quot;()\n&quot;);
            }
        }

        public class SquareDrawer : IDraw
        {
            public void Draw()
            {
                Console.WriteLine(&quot;[]\n&quot;);
            }
        }

        static void Main(string[] args)
        {
            Console.WriteLine(&quot;What would you like to draw? 1:Circle or 2:Sqaure&quot;);
            
            int input;
            if (int.TryParse(Console.ReadLine(), out input))
            {
                Pencil pencil = null;
                
                switch (input)
                {
                    case 1:
                        pencil = new Pencil(new CircleDrawer());
                        break;
                    case 2:
                        pencil = new Pencil(new SquareDrawer());
                        break;
                    default:
                        return;
                }

                pencil.Draw();

                Console.WriteLine(&quot;Press any key to exit...&quot;);
                Console.ReadKey();
            }
        }
    }

**Implemented Solution shown below** (Thanks to all who responded!)
This solution got me to the point where the only thing I need to do to use a new **IDraw** object is to create it.

    public class Pencil
        {
            private IDraw drawer;

            public Pencil(IDraw iDrawer)
            {
                drawer = iDrawer;
            }

            public void Draw()
            {
                drawer.Draw();
            }
        }

        public interface IDraw
        {
            int ID { get; }
            void Draw();
        }

        public class CircleDrawer : IDraw
        {
              
            public void Draw()
            {
                Console.Write(&quot;()\n&quot;);
            }

            public int ID
            {
                get { return 1; }
            }
        }

        public class SquareDrawer : IDraw
        {
            public void Draw()
            {
                Console.WriteLine(&quot;[]\n&quot;);
            }

            public int ID
            {
                get { return 2; }
            }
        }

        public static class DrawingBuilderFactor
        {
            private static List&lt;IDraw&gt; drawers = new List&lt;IDraw&gt;();

            public static IDraw GetDrawer(int drawerId)
            {
                if (drawers.Count == 0)
                {
                    drawers =  Assembly.GetExecutingAssembly()
                                       .GetTypes()
                                       .Where(type =&gt; typeof(IDraw).IsAssignableFrom(type) &amp;&amp; type.IsClass)
                                       .Select(type =&gt; Activator.CreateInstance(type))
                                       .Cast&lt;IDraw&gt;()
                                       .ToList();
                }

                return drawers.Where(drawer =&gt; drawer.ID == drawerId).FirstOrDefault();
            }
        }

        static void Main(string[] args)
        {
            int input = 1;

            while (input != 0)
            {
                Console.WriteLine(&quot;What would you like to draw? 1:Circle or 2:Sqaure&quot;);

                if (int.TryParse(Console.ReadLine(), out input))
                {
                    Pencil pencil = null;

                    IDraw drawer = DrawingBuilderFactor.GetDrawer(input);

                    pencil = new Pencil(drawer); 
                    pencil.Draw();
                }
            }
        }

Strategy Pattern with no &#39;switch&#39; statements?

How would you configure annotations in the following example code? I&#39;d like to stick with JPA annotations only and avoid Hibernate specific dependencies. **Is the code below correct?**

    @Entity
    public class RefExample extends RefData {
    	
    }

(There will be multiple versions of these classes, RefSomeOtherExample, etc, and one db table per class. Some may add additional fields (columns) but most will simply make use of the basic fields inherited from the &quot;RefData&quot; base class.)

Base class:

    @Entity
    public abstract class RefData {
    	
    	private long id;
    	private String code;
    	private String desc;
    	
    	@Id
    	@GeneratedValue(strategy = GenerationType.IDENTITY)
    	@Column(unique = true, nullable = false)
    	public long getId() {
    	
    		return id;
    	}
    	
    	public void setId(long id) {
    	
    		this.id = id;
    	}
    	
    	@Column(unique = true, nullable = false, length=8)
    	public String getCode() {
    	
    		return code;
    	}
    	
    	public void setCode(String code) {
    	
    		this.code = code;
    	}
    	
    	@Column(unique = true, nullable = false, length=80)
    	public String getDesc() {
    	
    		return desc;
    	}
    	
    	public void setDesc(String desc) {
    	
    		this.desc = desc;
    	}
    }

Ultimately I&#39;d like to generate schema creation scripts from this using Hibernate&#39;s SchemaExport class.  In the case above these two classes should only result in the creation of a single table named &quot;RefExample&quot; with the three columns from &quot;RefData&quot;. Will this work?

Inherited abstract class with JPA (+Hibernate)

How to convert from float to bigDecimal  in java?

How to convert from float to bigDecimal in java?

<p>How to convert from float to bigDecimal  in java?</p>


I installed Netbeans and tryed to access the server&#39;s manager using: (id/pass)manager/manager, admin/admin, system/password... None of them worked. 

What is the default username and password in Tomcat?

I have the following code:

    public class Tests {
    	public static void main(String[] args) throws Exception {
    		int x = 0;
    		while(x&lt;3) {
    			x = x++;
    			System.out.println(x);
    		}
    	}
    }

We know he should have writen just `x++` or `x=x+1`, but on `x = x++` it should first attribute `x` to itself, and later increment it. Why does `x` continue with `0` as value?

**--update**

Here&#39;s the bytecode:

    public class Tests extends java.lang.Object{
    public Tests();
      Code:
       0:	aload_0
       1:	invokespecial	#1; //Method java/lang/Object.&quot;&lt;init&gt;&quot;:()V
       4:	return
    
    public static void main(java.lang.String[])   throws java.lang.Exception;
      Code:
       0:	iconst_0
       1:	istore_1
       2:	iload_1
       3:	iconst_3
       4:	if_icmpge	22
       7:	iload_1
       8:	iinc	1, 1
       11:	istore_1
       12:	getstatic	#2; //Field java/lang/System.out:Ljava/io/PrintStream;
       15:	iload_1
       16:	invokevirtual	#3; //Method java/io/PrintStream.println:(I)V
       19:	goto	2
       22:	return
    
    }

I&#39;ll read about the [instructions][1] to try to understand...


  [1]: http://en.wikipedia.org/wiki/Java_bytecode_instruction_listings

Why does this go into an infinite loop?

I am HTTP POST-ing to URL http://laptop:8080/apollo/services/rpc?cmd=execute

with
POST data

```json
{ &quot;jsondata&quot; : &quot;data&quot; }
```

Http request has Content-Type of `application/json; charset=UTF-8`

How do I get the POST data (jsondata) from HttpServletRequest?

If I enumerate the request params, I can only see one param, 
which is &quot;cmd&quot;, not the POST data.



HttpServletRequest get JSON POST data

How can I extract a `.war` file with Linux command prompt?

Linux command for extracting war file?

I have the following logback.xml file:


    &lt;configuration debug=&quot;true&quot;&gt; 

    &lt;appender name=&quot;STDOUT&quot; class=&quot;ch.qos.logback.core.ConsoleAppender&quot;&gt; 
    &lt;encoder&gt;
      &lt;pattern&gt;%d{HH:mm:ss.SSS} [%thread] %-5level %logger{36} - %msg%n&lt;/pattern&gt;
    &lt;/encoder&gt;
    &lt;/appender&gt;

    &lt;root level=&quot;debug&quot;&gt;
      &lt;appender-ref ref=&quot;STDOUT&quot; /&gt;
    &lt;/root&gt;
    &lt;/configuration&gt;

Now, upon the occurrence of a specific event, I want to programmatically change the level of the root logger from _debug_ to _error_. I can&#39;t use variable substitution, it is mandatory that I do this within the code.

How can it be done ? Thanks.

How to change root logging level programmatically for logback

Can someone point towards (or show) some good general floating point comparison functions in C# for comparing floating point values? I want to implement functions for `IsEqual`, `IsGreater` an `IsLess`. I also only really care about doubles not floats. 

Floating point comparison functions for C#

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

How do I get the numbers after a decimal point?

For example, if I have `5.55`, how do i get `.55`?

How to get numbers after decimal point?

I encountered negative zero in output from python; it&#39;s created for example as follows:

    k = 0.0
    print(-k)

The output will be `-0.0`.

However, when I compare the `-k` to 0.0 for equality, it yields True. Is there any difference between `0.0` and `-0.0` (I don&#39;t care that they presumably have different internal representation; I only care about their behavior in a program.) Is there any hidden traps I should be aware of?

negative zero in python

Is there any (non-microoptimization) performance gain by coding

    float f1 = 200f / 2

in comparision to

    float f2 = 200f * 0.5

A professor of mine told me a few years ago that floating point divisions were slower than floating point multiplications without elaborating the why.

Does this statement hold for modern PC architecture?

**Update1**

In respect to a comment, please do also consider this case:


    float f1;
    float f2 = 2
    float f3 = 3;
    for( i =0 ; i &lt; 1e8; i++)
    {
      f1 = (i * f2 + i / f3) * 0.5; //or divide by 2.0f, respectively
    }


**Update 2**
Quoting from the comments:

&gt; [I want] to know what are the algorithmic / architectural requirements that cause &gt; division to be vastly more complicated in hardware than multiplication


Floating point division vs floating point multiplication

What is the difference between this two call? (Is there any?)

    // 1.
    new BigDecimal(&quot;3.53456&quot;).round(new MathContext(4, RoundingMode.HALF_UP));
    // 2.
    new BigDecimal(&quot;3.53456&quot;).setScale(4, RoundingMode.HALF_UP);

BigDecimal setScale and round

Actually, I&#39;ve found possible solution 

    //returns true
    new BigDecimal(&quot;5.50&quot;).doubleValue() == new BigDecimal(&quot;5.5&quot;).doubleValue()

Of course, it can be improved with something like `Math.abs (v1 - v2) &lt; EPS` to make the comparison more robust, but the question is whether this technique acceptable or is there a better solution?

If someone knows why java designers decided to implement BigDecimal&#39;s equals in that way, it would be interesting to read.

Why BigDecimal(&quot;5.50&quot;) not equals to BigDecimal(&quot;5.5&quot;) and how to work around this issue?

I have Hibernate method which returns me a BigDecimal.
I have another API method to which I need to pass that number but it accepts Integer as parameter. I cannot change return types or variable types of both methods. 

Now how to convert the BigDecimal into Integer and pass it to second method?

Is there a way out of this?


Converting BigDecimal to Integer

I need the following results

    100.12 -&gt; 100.00
    100.44 -&gt; 100.00
    100.50 -&gt; 101.00
    100.75 -&gt; 101.00

`.round()` or `.setScale()` ? How do I go about this?

Java BigDecimal: Round to the nearest whole value

How can I compare if `BigDecimal` value is greater than zero?

Content Type	Original Author	Original Content on Stackoverflow
Question	akp	View Question on Stackoverflow
Solution 1 - Java	dogbane	View Answer on Stackoverflow
Solution 2 - Java	Spacemonkey	View Answer on Stackoverflow
Solution 3 - Java	Maurice Perry	View Answer on Stackoverflow
Solution 4 - Java	Johnny Blaze	View Answer on Stackoverflow

How to convert from float to bigDecimal in java?

Java Problem Overview

Java Solutions

Solution 1 - Java

Solution 2 - Java

Solution 3 - Java

Solution 4 - Java

Inherited abstract class with JPA (+Hibernate)

Strategy Pattern with no 'switch' statements?

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