JTree In Java

Constructors in JTree

There are three constructors that are typically present in the Jtree class, and they are:

• Jtree (): A function Object() constructor with the same name as the class and no return value is called Jtree. It generates a simple model for the JTree class.
• JTree (Object value[]): An object is passed through the function Object() constructor in this scenario. All of the objects transferred are children of the root node, which is represented at a lower level.
• Jtree (TreeNode root): The root node in this case is TreeNode, which is constructed using the commands provided. The root node TreeNode will include all of the child nodes.

Methods in JTree

The following are some of the methods:

• Public TreeModel getModel(): The model of the tree whose data is displayed using the Jtree in Java programming language is displayed by public TreeModel getModel ().
• Public int getRowCount(): This function is used to count the number of rows in the Jtree. The number of rows also mentions the number of child nodes that are present under the root node of the Jtree.
• Public void addTreeSelectionListener(TreeSelectionListener): This method helps us to add a listener to the tree selection in the JTree panel.

Example of JTree in Java

Jtree is a component of the Swing approach and is derived from it. The javax.swing file is imported first, followed by the creation of the Class Example. In the software, there is a single root node and numerous child nodes. Different types of nodes can be built under a single root node.

A Jtree is a programming concept that is used to establish a hierarchy. The first appears at the top, while the last appear at the bottom. A root node that is created can have sub-nodes. This is an example of a programme in which hierarchy appears first, followed by the variables that are present. Due to the fact that Java is an object-oriented programming language, a Default Mutable Tree Node is provided before the nodes are constructed.

In the example below, we are creating India as a root node and its child node is cities. Under the cities node, there are various cities. Under each city node, it has its means of transport with its name.

Code

import javax.swing.*;
import javax.swing.tree.DefaultMutableTreeNode;
public class tree
{
	JFrame f;
	tree()
	{
		f=new JFrame();

		// defining country and cities node
		DefaultMutableTreeNode country = new DefaultMutableTreeNode("India");
		DefaultMutableTreeNode cities = new DefaultMutableTreeNode("Cities");

		// adding cities node to country
		country.add(cities);

		// defining cities
		DefaultMutableTreeNode bombay = new DefaultMutableTreeNode("Bombay");
		DefaultMutableTreeNode delhi = new DefaultMutableTreeNode("Delhi");
		DefaultMutableTreeNode kolkata = new DefaultMutableTreeNode("Kolkata");
		DefaultMutableTreeNode chennai = new DefaultMutableTreeNode("Chennai");
		DefaultMutableTreeNode banglore = new DefaultMutableTreeNode("Banglore");
		DefaultMutableTreeNode hyderabad = new DefaultMutableTreeNode("Hyderabad");

		// adding cities
		cities.add(bombay); 
		cities.add(delhi);
		cities.add(kolkata);
		cities.add(chennai);
		cities.add(banglore);
		cities.add(hyderabad);

		// defining public transport to each cities
		DefaultMutableTreeNode tbombay = new DefaultMutableTreeNode("Transport in Bombay");
		DefaultMutableTreeNode tdelhi = new DefaultMutableTreeNode("Transport in  Delhi");
		DefaultMutableTreeNode tkolkata = new DefaultMutableTreeNode("Transport in Kolkata");
		DefaultMutableTreeNode tchennai = new DefaultMutableTreeNode("Transport in Chennai");
		DefaultMutableTreeNode tbanglore = new DefaultMutableTreeNode("Transport in Banglore");
		DefaultMutableTreeNode thyderabad = new DefaultMutableTreeNode("Transport in Hyderabad");

		// adding public transport to each cities
		bombay.add(tbombay); 
		delhi.add(tdelhi);
		kolkata.add(tkolkata);
		chennai.add(tchennai);
		banglore.add(tbanglore);
		hyderabad.add(thyderabad); 

		// adding transport details in each city
		// for bombay city
		DefaultMutableTreeNode CSIA = new DefaultMutableTreeNode("Chhatrapati Shivaji International Airport");
		DefaultMutableTreeNode CSTRS = new DefaultMutableTreeNode("Chhatrapati Shivaji Terminus Railway Station");
		DefaultMutableTreeNode MCBS = new DefaultMutableTreeNode("Mumbai Central Bus Station");
		tbombay.add(CSIA); tbombay.add(CSTRS); tbombay.add(MCBS);

		// for delhi city
		DefaultMutableTreeNode IGIA = new DefaultMutableTreeNode("Indira Gandhi International Airport");
		DefaultMutableTreeNode HNRS = new DefaultMutableTreeNode("Hazrat Nizamuddin Railway Station");
		DefaultMutableTreeNode MPISBT = new DefaultMutableTreeNode("Maharana Pratap Inter State Bus Terminus");
		tdelhi.add(IGIA); tdelhi.add(HNRS); tdelhi.add(MPISBT);

		// for kolkata city
		DefaultMutableTreeNode NSCBIA = new DefaultMutableTreeNode("Netaji Subhas Chandra Bose International Airport");
		DefaultMutableTreeNode HRS = new DefaultMutableTreeNode("Howrah Railway Station");
		DefaultMutableTreeNode EBT = new DefaultMutableTreeNode("Esplanade Bus Terminus");
		tkolkata.add(NSCBIA); tkolkata.add(HRS); tkolkata.add(EBT);

		// for chennai city
		DefaultMutableTreeNode MIMA = new DefaultMutableTreeNode("Madras International Meenambakkam Airport");
		DefaultMutableTreeNode CCRS = new DefaultMutableTreeNode("Chennai Central Railway Station");
		DefaultMutableTreeNode CMBT = new DefaultMutableTreeNode("Chennai Mofussil Bus Terminus");
		tchennai.add(MIMA); tchennai.add(CCRS); tchennai.add(CMBT);

		// for banglore city
		DefaultMutableTreeNode KIA = new DefaultMutableTreeNode("Kempegowda International Airport");
		DefaultMutableTreeNode KSRRS = new DefaultMutableTreeNode("Krantivira Sangolli Rayanna Railway Station");
		DefaultMutableTreeNode MBT = new DefaultMutableTreeNode("Majestic Bus Terminus");
		tbanglore.add(KIA); tbanglore.add(KSRRS); tbanglore.add(MBT);

		// for hyderabad city
		DefaultMutableTreeNode RGIA = new DefaultMutableTreeNode("Rajiv Gandhi International Airport");
		DefaultMutableTreeNode HDRS = new DefaultMutableTreeNode("Hyderabad Deccan Railway Station");
		DefaultMutableTreeNode MGBS = new DefaultMutableTreeNode("Mahatma Gandhi Bus Station");
		thyderabad.add(RGIA); thyderabad.add(HDRS); thyderabad.add(MGBS); 
		///////////////

		JTree jt=new JTree(country);
		f.add(jt);
		f.setSize(200,200);
		f.setVisible(true);
	}
	public static void main(String[] args) 
	{
		new tree();
	}
}

You can also try this code with Online Java Compiler

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Output

Frequently Asked Questions

What is JTree in Java?

The JTree class is used to display hierarchical or tree-structured data. JTree is a sophisticated component. It has a top-most 'root node,' which serves as a parent for all nodes in the tree. It is a descendant of the JComponent class.

Which class creates a node in JTree?

To create a node, use the DefaultMutuableTreeNode class.

What is the default mutable tree node?

DefaultMutableTreeNode has methods for inspecting and altering a node's parent and children, as well as procedures for inspecting the tree in which the node is located.

What is JTable in Java?

The JTable is a two-dimensional cell table that may be seen and edited.

What is MVC in Swing?

Swing's model-view-controller architecture (MVC) serves as the foundation for all of its components. MVC divides user interface components into three parts. Each of these elements has a significant impact on how the component functions.

Conclusion

In this article, we have discussed the use of JTree in Java. Also, we have seen the practical implementation of the JTree.

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