What are the common causes of NumberFormatException in Java?

What are the common causes of NumberFormatException in Java?

Java is an object-oriented programming language with a wide range of application scenarios. In Java, NumberFormatException is a common error. This exception usually occurs when trying to convert a string to a numeric data type (such as int, double, etc.). There may be many reasons for this exception. Here are some common reasons:

1. Invalid string format

When the string does not meet the number format requirements, A NumberFormatException will be thrown. For example, when a string contains characters other than numeric characters (such as letters, symbols, etc.), the string does not conform to the numeric format. If you try to convert this string to a numeric data type, a NumberFormatException will be thrown.

For example, in the following code, if the string "123abc" is converted to an integer type, a NumberFormatException exception will be thrown:

String str = "123abc";
int num = Integer.parseInt(str);

2. String out of range

When the value represented by the string exceeds the range of the target data type, a NumberFormatException exception will be thrown. For example, when converting a large integer to a byte type, the integer exceeds the range of the byte type, causing an exception to be thrown.

For example, in the following code, converting a large integer to byte type will throw a NumberFormatException:

int num = 300;
byte b = (byte) num;

3. The string is empty

NumberFormatException will also be thrown when trying to convert an empty string to a numeric data type. Because an empty string does not contain any numeric characters, it cannot be converted to a number.

For example, in the following code, converting an empty string to an integer type will throw a NumberFormatException exception:

String str = "";
int num = Integer.parseInt(str);

In short, the NumberFormatException exception is usually due to the string not conforming to the number format. It is caused by reasons such as requirements, exceeding the data type range or an empty string. When writing Java code, pay attention to handling this exception to avoid program errors. For example, you can use try-catch statements to surround code blocks that may throw this exception. When an exception is thrown, you can handle the exception in the catch block to ensure the normal operation of the program.

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