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Java Articles
Page 146 of 450
How to overwrite a line in a .txt file using Java?
The given task is to overwrite a line in a .txt file with new content. Assume we have a .txt file with the following content - Line 1: Hello World Line 2: This is a test file. Line 3: This line will be overwritten. Line 4: Goodbye! We want to overwrite line 3 with "This line has been changed". Following will be the resultant content - line 1: Hello World line 2: This is a test file. line 3: This line has been changed. line 4: Goodbye! Overwriting a Line in a ".txt" File There are no direct methods ...
Read MoreHow can we insert multiple tabs into a single JTabbedPane in Java?
In this article, we will learn to insert multiple tabs into a single JTabbedPane in Java. The Java Swing's JTabbedPane enables you to group content into several tabs in one container. JTabbedPane A JTabbedPane is a component can extends the JComponent class, and we can able to see only one tab at a time. Each tab is associated with a single component that can be displayed when the tab is selected. Syntax Object declaration and instantiation using the Java class JTabbedPane: JTabbedPane tabbedPane = new JTabbedPane(); A JTabbedPane can generate a ChangeListener interface when a tab is ...
Read MoreHow can we prevent the re-ordering columns of a JTable in Java?
JTable component in Swing provides an effective method for showing and editing tabular information. JTable automatically supports re-ordering columns through dragging of column headers by default. In this article, we will learn to prevent the re-ordering of columns of a JTable in Java. JTable A JTable is a subclass of the JComponent class, and it can be used to create a table with information displayed in multiple rows and columns. Syntax The following is the syntax for JTable initialization: JTable table = new JTable(data, columnNames); When a value is selected from a JTable, a TableModelEvent is generated, which is handled ...
Read MoreHow to display a bold text inside the JTextArea in Java?\\n
JTextArea is one of the most common Swing-based components. By default, it does not support text formatting such as bold, italics, or colored text inside a textarea. In this article, we will learn to display bold text inside the JTextArea in Java. What is a JTextArea? A JTextArea class can extend JTextComponent and allow a user to enter multiple lines of text inside it. A JTextArea can generate a CaretListener interface, which can listen to caret update events. Syntax The following is the syntax for JTextArea initialization: JTextArea textArea = new JTextArea(); Adding Bold Text Inside the JTextArea We ...
Read MoreHow can we implement an editable JLabel in Java?\\n
In this article, we will learn to implement an editable JLabel in Java. An editable JLabel is a label component that can be converted to an editable text field when clicked. JLabel A JLabel class can extend the JComponent class, and an object of JLabel provides text instructions or information on a GUI. A JLabel can display a single line of read-only text, an image, or both text and image. Syntax The following is the syntax for JLabel initialization: JLabel label = new JLabel("Tutorials Point"); A JLabel can explicitly generate a PropertyChangeListener interface. Methods The important methods of a ...
Read MoreCustom instance creator using Gson in Java?
While parsing a JSON String to or from a Java object, by default, Gson tries to create an instance of the Java class by calling the default constructor. In the case of Java, if a class doesn’t contain a default constructor or we want to do some initial configuration while creating Java objects, we need to create and register our own instance creator. Custom Instance Creator Using Gson Custom instance means creating a new instance that is not the default. In this instance, we can add whatever properties we want. There are many libraries that create custom instances. In this ...
Read MoreHow to deserialize a JSON to Java object using the flexjson in Java?
Deserializing a JSON to a Java object means converting a JSON string into a Java object.The deserialize() Method of the Flexjson Library We will be using the Flexjson library to deserialize a JSON to a Java object in Java. The Flexjson library is a lightweight library that is used for serializing as well as deserializing Java objects to and from JSON. A JSONDeserializer is the main class for performing deserialization of JSON to Java objects. We can deserialize a JSON string to a Java object using the deserialize(String json, Class type) method of JSONDeserializer. Syntax of deserialize() Method The syntax of the ...
Read MoreHow to ignore the null and empty fields using the Jackson library in Java?\\n
The Jackson is a library for Java and it has very powerful data binding capabilities and it also provides a framework to serialize custom java objects to JSON and deserialize JSON back to Java object. Ignoring Null and Empty Fields Using Jackson The Jackson library provides @JsonInclude annotation, which controls the serialization of a class as a whole or its individual fields based on their values during serialization. The @JsonInclude annotation contains below two values: Include.NON_NULL: Indicates that only properties with not null values will be included in JSON. Include.NON_EMPTY: Indicates ...
Read MoreHow can we change a field name in JSON using Jackson in Java?
When we have a JSON object and want to change a specific field name for some reason, we can use the Jackson library in Java.The Jackson Annotation @JsonProperty The Jackson Annotation @JsonProperty is used on a property or method during the serialization or deserialization of JSON. It takes an optional 'name' parameter, which is useful in case the property name is different from the key name in JSON. By default, if the key name matches the property name, the value is mapped to the property value. If the key name is different, we can use the @JsonProperty annotation to ...
Read MoreHow to exclude a field from JSON using @Expose annotation in Java?
Sometimes we need to exclude certain fields from the JSON output. For example, if we have a field that contains sensitive information, we may not want to include it in the JSON representation of the object. In such cases, we can use the Expose annotation provided by Gson. The Gson @Expose annotation The Gson @Expose annotation can be used to specify whether a field isto be exposed or not (included or not). The @Expose annotation can take two parameters, and each parameter is a boolean which can take either the value true or false. The two parameters are: ...
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