Convert string to double precision floating point number using java's Double.parseDouble() function

Use Java's Double.parseDouble() function to convert a string into a double-precision floating point number

In Java programming, we often need to convert a string into a numeric type. For double-precision floating-point numbers, Java provides a very convenient method, the Double.parseDouble() function. This article will introduce the usage of this function and attach some sample code to help readers better understand and use this function.

Double.parseDouble() function is a static method provided by the Java library, used to convert a string to a double-precision floating point number type (double). Its syntax is as follows:

public static double parseDouble(String s) throws NumberFormatException

The parameter s is the string to be converted to a double precision floating point number. This function will return a double type value. If the string cannot be converted to a valid double-precision floating point number, a NumberFormatException is thrown.

Here is a simple sample code that demonstrates how to use the Double.parseDouble() function to convert a string to a double precision floating point number:

public class DoubleParseDemo {
    public static void main(String[] args) {
        String numberStr = "3.14";
        double number = Double.parseDouble(numberStr);
        System.out.println("转换后的双精度浮点数为：" + number);
    }
}

In the above example, we convert the character The string "3.14" is assigned to a variable named numberStr. Then, use the Double.parseDouble() function to convert the string to a double precision floating point number and save the result in a variable called number. Finally, use the System.out.println() function to print out the converted double-precision floating point number.

Run the above code, the output result is:

转换后的双精度浮点数为：3.14

In addition to converting simple floating point strings to double precision floating point numbers, the Double.parseDouble() function can also handle scientific notation representation String. For example, the following code demonstrates how to convert the string "1.23e 10" to a double-precision floating point number:

public class DoubleParseDemo {
    public static void main(String[] args) {
        String numberStr = "1.23e+10";
        double number = Double.parseDouble(numberStr);
        System.out.println("转换后的双精度浮点数为：" + number);
    }
}

Run the above code, the output result is:

转换后的双精度浮点数为：1.23E10

It should be noted that, If the string cannot be converted to a valid double-precision floating point number, the Double.parseDouble() function will throw a NumberFormatException exception. Therefore, when using this function, we should add the corresponding exception handling mechanism to prevent the program from crashing.

In summary, using the Double.parseDouble() function in Java can easily convert a string into a double-precision floating point number. This function works well for conversions from simple floating-point strings to strings represented in scientific notation. But we need to pay attention to handling exceptions to ensure the stability and reliability of the program. I hope the introduction and sample code in this article can be helpful to readers.

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