Convert float to String and String to float in Java

Question

How could I convert from float to string or string to float?

In my case I need to make the assertion between 2 values string (value that I have got from table) and float value that I have calculated.

String valueFromTable = "25";
Float valueCalculated =25.0;

I tried from float to string:

String sSelectivityRate = String.valueOf(valueCalculated);

but the assertion fails

Solution 1

Using Java’s Float class.

float f = Float.parseFloat("25");
String s = Float.toString(25.0f);

To compare it's always better to convert the string to float and compare as two floats. This is because for one float number there are multiple string representations, which are different when compared as strings (e.g. "25" != "25.0" != "25.00" etc.)

Solution 2

Float to string - String.valueOf()

float amount=100.00f;
String strAmount=String.valueOf(amount);
// or  Float.toString(float)

String to Float - Float.parseFloat()

String strAmount="100.20";
float amount=Float.parseFloat(strAmount)
// or  Float.valueOf(string)

Solution 3

You can try this sample of code:

public class StringToFloat
{

  public static void main (String[] args)
  {

    // String s = "fred";    // do this if you want an exception

    String s = "100.00";

    try
    {
      float f = Float.valueOf(s.trim()).floatValue();
      System.out.println("float f = " + f);
    }
    catch (NumberFormatException nfe)
    {
      System.out.println("NumberFormatException: " + nfe.getMessage());
    }
  }
}

found here

Solution 4

I believe the following code will help:

float f1 = 1.23f;
String f1Str = Float.toString(f1);      
float f2 = Float.parseFloat(f1Str);

Solution 5

If you're looking for, say two decimal places.. Float f = (float)12.34; String s = new DecimalFormat ("#.00").format (f);

View more solutions

Comments

[xtofl]

you are aware that float values are never precise?

[Vishy]

Do you want to compare them as String or as float values? This is not the same thing. float is less precise than double and either can have rounding errors from calculated values.

[Vishy]

google not to be confused with googol. ;)

[lola]

I tried you solution and also from goggle but when I make the assertion I got :java.lang.AssertionError: expected:<25> but was:<25.0>

[Hein du Plessis]

Thanks - helped me, needed the catch bit ;)

[Jonathan]

Do i need to import something for this to work? I get undefied type 'Float' (I'm in a weird java environment though, openhab scripts)