Java library that has parseInt, parseLong, parseDouble, etc that accept default values and don't throw exceptions?

问题:

I like the suggestion in String to Int in java - Likely bad data, need to avoid exceptions to implement a utility method that parses an int, but returns a default value if the string cannot be parsed.

public static int parseInt(String s, int defaultValue) {     if (s == null) return defaultValue;     try {          return Integer.parseInt(s);      } catch (NumberFormatException x) {          return defaultValue;      }   } 

Is there an existing open source library (from apache commons, or google, for example) that implements this as well as for other data types such as boolean, float, double, long, etc?

回答1:

Apache Commons Lang has the class org.apache.commons.lang3.math.NumberUtils with convenient methods for convert. In another way, you can specify a default value if there is a error. e.g.

NumberUtils.toLong("")         => 0L NumberUtils.toLong(null, 1L)   => 1L  NumberUtils.toByte(null)       => 0 NumberUtils.toByte("1", 0)     => 1 

回答2:

Guava has several tryParse methods that return null on a failed parse, e.g. Ints.tryParse, Floats.tryParse, etc

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