Solution to NumberFormatException exception in Java

An exception that often occurs in Java is NumberFormatException. This is because when using a string to parse a number, if the string contains non-numeric characters, this exception will be triggered. This article will introduce the solution to the NumberFormatException exception.

1. Form verification

In a form for inputting numbers, in order to prevent users from making mistakes, verification is generally required. For example, you can use regular expressions to check whether the input string is a number. If it is not a number, an exception is thrown. The following is an example:

String input = "abc123";
if (!input.matches("\d+")) {
    throw new NumberFormatException("输入的不是数字！");
}
int num = Integer.parseInt(input);

2. Exception catching

In the program, if you clearly know that the input string may contain non-numeric characters, you can solve the NumberFormatException by exception catching abnormal. The following is an example:

String input = "abc123";
try {
    int num = Integer.parseInt(input);
} catch (NumberFormatException e) {
    System.out.println("输入的不是数字！");
    e.printStackTrace();
}

3. Default value for converting string to number

In some cases, in order to avoid program interruption due to NumberFormatException exception, you can set Default value for converting string to number. For example, if the input is a null character, the default number is 0. The following is an example:

String input = "";
int num;
try {
    num = Integer.parseInt(input);
} catch (NumberFormatException e) {
    num = 0;
}
System.out.println(num); // 输出0

4. Check whether the string is empty

When using a string to convert a number, you need to pay attention to whether the input string is empty. If the input string is empty, conversion cannot occur. Therefore, it is recommended to first determine whether the string is empty before performing the conversion operation. The following is an example:

String input = "";
if (input != null && input.length() > 0) {
    int num = Integer.parseInt(input);
} else {
    System.out.println("输入的字符串为空，无法转为数字！");
}

In short, when converting a string to a number, pay attention to whether the entered characters are numbers and whether they are empty. If necessary, you can use exception catching to handle NumberFormatException exceptions. Through these methods, NumberFormatException exceptions can be solved more efficiently.

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