Java Program to Convert String to Float Value

Last Updated : 05 Aug, 2021
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Given a string “str” in Java, the task is to convert this string to float type.

Methods:

This can be done by two methods as listed below:

  1. Using parseFloat() Method 
  2. Using valueOf() Method 

Let us discuss above two ways of implementing the methods to get a fair understanding of the conversion of string to float values.

Method 1: Using parseFloat()

The parseFloat() method in Float Class is a built-in method in Java that returns a new float initialized to the value represented by the specified String, as done by the valueOf method of class Float.

Syntax:

public static float parseFloat(String s) ;

Parameters: It accepts a single mandatory parameter s which specifies the string to be parsed.

Return type: It returns e float value represented by the string argument.

Exceptions:

  • NullPointerException: When the string parsed is null
  • NumberFormatException: When the string parsed does not contain a parsable float

Example 1

Java 
// Java Program to Convert String to Float Value by
// Implementing parseFloat() method of Float class

// Importing input output classes
import java.io.*;

// Main class
class GFG {

    // Main driver method
    public static void main(String[] args)
    {
        // Input string
        String str = "100";

        // Returning the float value
        // represented by the string argument
        float val = Float.parseFloat(str);

        // Prints the float value of the string
        System.out.println("String is converted to float "
                           + val);
    }
}

Output
String is converted to float 100.0

Example 2: To show unsuccessful conversion 

Java 
// Java Program to Convert String to Float Value by
// Implementing parseFloat() method of Float class
// Where Exception Message is thrown

// Importing input output classes
import java.io.*;

// Main class
class GFG {

   // Method 1
   // To convert string to float
   public static void convertStringToFloat(String str) {

      float floatValue;

      // Try block to check for exceptions
      try {

         // Convert string to float
         // using parseFloat() method
         floatValue = Float.parseFloat(str);

         // Print the expected float value
         System.out.println(
            str
            + " after converting into float = "
            + floatValue);
      }

      // Catch block to handle the exception
      catch (Exception e) {

         // Print the exception message
         // using getMessage() method
         System.out.println(
            str
            + " cannot be converted to float: "
            + e.getMessage());
      }
   }

   // Method 2
   // Main driver code
   public static void main(String[] args) {

      // Declaring and initializing custom strings values
      String str1 = "";
      String str2 = null;
      String str3 = "GFG";

      // Convert string to float
      // using parseFloat() method
      convertStringToFloat(str1);
      convertStringToFloat(str2);
      convertStringToFloat(str3);
   }
}

Output:

Method 2: Using valueof() method 

The valueOf() method of the Float class converts data from its internal form into human-readable form. The valueOf() method converts data from its internal form into a human-readable form. It is a static method that is overloaded within a string for all of Java’s built-in types so that each type can be converted properly into a string.  

It is called when a string representation of some other type data is needed-for example during concatenation operation.you can call this method with any data type and get a reasonable String representation valueOf() returns java.lang.Integer, which is the object representative of the integer Few forms of valueOf()

Syntax:

Float.valueOf(str);

Returns:  

  • It returns string representation of given value
  • valueOf(iNum); // Returns the string representation of int iNum.
  • String.valueOf(sta); // Returns the string representation of the boolean argument.
  • String.valueOf(fNum); // Returns the string representation of the float fnum.
  • String.valueOf(data, 0, 15); // Returns the string representation of a specific subarray of the chararray argument.
  • String.valueOf(data, 0, 5); // Returns the string of charArray 0 to 5
  • String.valueOf(data, 7, 9); // Returns the string of charArray starting index 7 and total count from 7 is 9.

Example

Java 
// Java Program to Convert String to Float Value
// Using valuesOf() method

// Importing input output classes
import java.io.*;

// Main class
class GFG {

    // Method 1
    // To convert String to Float
    public static float convertStringToFloat(String str)
    {
        // Convert string to float
        // using valueOf() method
        return Float.valueOf(str);
    }

    // Method 2
    // Main driver method
    public static void main(String[] args)
    {

        // Custom input string value
        String stringValue = "1.0";

        // Expected float value
        float floatValue;

        // Converting string to float
        floatValue = convertStringToFloat(stringValue);

        // Printing  the expected float value
        System.out.println(
            stringValue + " after converting into float = "
            + floatValue);
    }
}

Output
1.0 after converting into float = 1.0


 


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