Start a Java class and hits this java.lang.UnsupportedClassVersionError, what is class file version 52 56?

Date: 2019-08-11 View: 1344

How to check which JDK version compiled the class?

In Java, we can use javap -verbose className to print out the class information.

Date: 2019-08-11 View: 1161

In the old days, we can use list.toArray(new String[0]) to convert a ArrayList<String> into a String[]

Date: 2019-08-11 View: 1272

Gson provide simple toJson() and fromJson() methods to convert Java objects to / from JSON.

Date: 2019-08-11 View: 1350

Few Jackson examples to convert a JSON array string to a List

Date: 2019-08-11 View: 1527

In Jackson, we can use @JsonInclude(JsonInclude.Include.NON_NULL) to ignore the null fields.

Date: 2019-08-11 View: 1484

Jackson provide writeValue() and readValue() methods to convert Java objects to / from JSON.

Date: 2019-08-11 View: 1323

In Jackson, we can use @JsonView to limit or control fields display for different users.

Date: 2019-08-11 View: 1502

In Java, we can use (str != null && !str.isEmpty()) to make sure the String is not empty or null.

Date: 2019-08-11 View: 1166

Few Java examples to show you how to check if a String is numeric.

Date: 2019-08-11 View: 1208

In this tutorial, we will show you how to parse JSON with JSON.simple

Date: 2019-08-11 View: 1554

In Java, we can use new ArrayList<>(Arrays.asList(array)) to convert an Array into an ArrayList

Date: 2019-08-11 View: 1213

In Java, we can use Double.parseDouble() to convert a String to double

Date: 2019-08-11 View: 1488

Few Java examples to show you how to generate a random alphanumeric String, with a fixed length.

Date: 2019-08-11 View: 1395

A Java example to generate a strong, secure random password containing [a-zA-Z0-9!@#$%&*()_+-=[]?] characters, with a length of 15.

Date: 2019-08-11 View: 1284