In what scenarios does NumberFormatException occur in Java?

Java is an object-oriented programming language that is widely used in various development fields. In Java code, NumberFormatException sometimes occurs. This article will discuss in detail the occurrence scenarios of NumberFormatException exceptions in Java.

NumberFormatException is a runtime exception in Java, which indicates that the format is incorrect during the conversion of a string into a number and cannot be converted into the corresponding number type. In Java, there are some methods that need to convert strings to numeric types, such as: parseInt(), parseDouble(), parseByte(), etc. When a string does not meet the format for conversion to the corresponding numeric type, a NumberFormatException is thrown.

The following are several situations in which a NumberFormatException exception may occur:

1. The string is empty or does not meet the requirements

When a string is empty or When the format does not meet the requirements of the numeric type, for example: it contains non-numeric characters or has multiple decimal points, etc., a NumberFormatException will be thrown.

For example, the following code will throw a NumberFormatException:

String str1 = "";
int num1 = Integer.parseInt(str1);  //抛出NumberFormatException异常

2. The numerical type exceeds the range

When a string is converted to a numerical type , when it exceeds the scope of this type, a NumberFormatException will be thrown.

For example, the following code will throw a NumberFormatException exception:

String str2 = "2147483648";  //int范围是-2147483648 ~ 2147483647
int num2 = Integer.parseInt(str2);  //抛出NumberFormatException异常

3. Using the wrong base

When a string is in the wrong base When converting to a numeric type, a NumberFormatException will be thrown.

For example, the following code will throw a NumberFormatException:

String str3 = "A"; //按照十进制转换是有问题的
int num3 = Integer.parseInt(str3, 10); //抛出NumberFormatException异常

When selecting a base, it needs to match the original string. For example, "A" represents ten in hexadecimal and cannot be converted to decimal.

4. There are spaces in the string

When there are spaces in a string, a NumberFormatException exception will be thrown when it is converted to a numeric type.

For example, the following code will throw a NumberFormatException:

String str4 = "12 34"; //两个数字中间有空格
int num4 = Integer.parseInt(str4); //抛出NumberFormatException异常

When converting the string type, the non-numeric part needs to be removed, otherwise unpredictable results will occur.

Summary:

In Java development, developers need to handle NumberFormatException exceptions carefully, otherwise it will lead to unpredictable results in program operation. In the above situation, Java handles NumberFormatException exceptions in the same way as other runtime exceptions. You can use try...catch blocks for exception handling to ensure the robustness and effectiveness of the program.

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