How to Convert String to float in Java

To convert String to float in Java you can use one of the following options-

1- Float.parseFloat(String str)– Returns a new float initialized to the value represented by the specified String.

2- Float.valueOf(String s)– Returns a Float object holding the float value represented by the argument string s.

As you can see parseFloat() method returns a float primitive where as valueOf() method returns a Float object.

Java example to convert String to float using Float.parseFloat

public class StringToFloat {
  public static void main(String[] args) {
    String str = "56.45f";
    try{
      float f = Float.parseFloat(str);
      System.out.println("value - " + f);
      // can be used in arithmetic operations now
      System.out.println(f+"/3 = " + f/3);
    }catch(NumberFormatException exp){
      System.out.println("Error in conversion " + exp.getMessage());
      throw exp;
    }  
  }
}

Output

value - 56.45
56.45/3 = 18.816668

For float numbers you can use “f” or “F” (even d or D which denotes double) so a String like this – “56.45f” won’t result in NumberFormatException while converting. But having any other alphabet like “56.45c” will throw exception.

Java example to convert String to float using Float.valueOf

public class StringToFloat {

	public static void main(String[] args) {
		String str = "-55.67456";
		try{
			Float f = Float.valueOf(str);
			System.out.println("value- " + f);
		}catch(NumberFormatException exp){
			System.out.println("Error in conversion " + exp.getMessage());
			throw exp;
		}  
	}
}

Output

value- -55.67456

NumberFormatException

While converting string to float in Java NumberFormatException is thrown if an invalid number string is passed for conversion.

public class StringToFloat {

	public static void main(String[] args) {
		String str = "43g";
		try{
			Float f = Float.valueOf(str);
			System.out.println("value- " + f);
		}catch(NumberFormatException exp){
			System.out.println("Error in conversion " + exp.getMessage());
			throw exp;
		}  
	}
}

Output

Error in conversion For input string: "43g"
Exception in thread "main" java.lang.NumberFormatException: For input string: "43g"
	at sun.misc.FloatingDecimal.readJavaFormatString(Unknown Source)
	at sun.misc.FloatingDecimal.parseFloat(Unknown Source)
	at java.lang.Float.parseFloat(Unknown Source)
	at java.lang.Float.valueOf(Unknown Source)
	at com.knpcode.programs.StringToFloat.main(StringToFloat.java:8)

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