You can use i += 0.25 instead.

The lack of precision of double types is well-known. Usually, a solution is to use BigDecimal instead. However in your specific case, since you're stepping 0.1 at each iteration, you could also work with integers, and divide them by 10 when needed.

Note that you should also change the way you store the data. That is, use:

TreeMap<BigDecimal, Integer>

(or TreeMap<Integer, Integer>) instead of TreeMap<Double, Integer>

See also the documentation of BigDecimal: http://docs.oracle.com/javase/7/docs/api/java/math/BigDecimal.html It's not as easy to use as double, but much safer.

You could do something like this:

public static void FindTheDouble() {

double LookFor = 2.29195;

for (double i = 1.0; i <= 5.0; i+=0.00005) {
    System.out.println(i);
       if (i == LookFor) {
           System.out.println();
           System.out.println("Found the double: "+LookFor);
           break;          
       }   
   }
}

Your break statement is correct.

Your equality statement might fail with doubles. Instead you want to do something like this:

if (Math.abs((i - LookFor)) < 0.0000001)

The double can have extraneous values at extended decimal places that can interfere with the success of your equality comparison. Instead it is better to check that the two double values are within some degree of precision that is acceptable to you.

Your code is also reading the newline character('\n') as you are hitting the enter key('\n') after every input('1','2','3' etc).

If you type one character and press enter key,System.in.read() will read two characters as it also reads the newline character.

Re-factored your code a bit. Enter all the values in one line(do not press enter key until you enter all the values). This will solve your problem.

for (i = 0; i < 4; i++)
{
       a = (char)System.in.read();

       System.out.println(a);
 }

Input 4567

Output

4
5
6
7

The ideone code link is here http://ideone.com/IYcjyX. Hope it helps.

It's not a good idea to use floating point values as for-loop variables because of subtleties in arithmetic and comparison. Your loop might not iterate through the values you expect because of rounding errors. An out-by-one error is likely.

For example, this loop

 for (double x=0.0; x < 100.0; x += 0.1)

might be expected to pass through the values 0.0, 0.1, 0.2,... but because of rounding errors passes through slightly different values.

If you use a ListIterator<E> instead, you will be able to add. The reason you are getting the exception is b/c of this(from the javadocs):

The iterators returned by this class's iterator and listIterator methods are fail-fast: if the list is structurally modified at any time after the iterator is created, in any way except through the iterator's own remove or add methods, the iterator will throw a ConcurrentModificationException.

You cannot modify the list itself directly, but through the iterator, you may. The base Iterator<E> class does not have an add method, but ListIterator<E> does, which is what you are getting when you call the obj.listIterator() anywqay.