Servlet HTTP Methods GET, POST, PUT, DELETE: Tutorial, Examples, FAQs & Interview Tips

Servlet HTTP Methods GET, POST, PUT, DELETE

Servlet HTTP Methods GET, POST, PUT, DELETE is an important Servlet topic because it appears in real projects, debugging sessions, and interviews. Learn the meaning first, then connect it to a small working example so the rule does not stay abstract.

For this page, focus on what problem Servlet HTTP Methods GET, POST, PUT, DELETE solves, where developers usually make mistakes, and how to verify the result. The audit note for this lesson was: under 650 content words; limited checklist/practice/mistake/FAQ notes .

A strong understanding of Servlet HTTP Methods GET, POST, PUT, DELETE should include syntax, behavior, one realistic use case, one failure case, and one quick way to check your work with tools or output.

Servlet HTTP Methods GET POST PUT DELETE should be studied as a practical Servlet lesson, not as a label. Start by naming the input, the rule that changes the input, and the result a learner should be able to predict after reading the page.

In the servlet > http-methods page, the notes should connect the definition with a working scenario, a mistake that beginners actually make, and the exact check that proves the fix. That makes the topic useful for coding, debugging, and interview revision.

HTTP Methods in Servlets

HttpServlet provides a separate method for each HTTP verb. You override only the methods your Servlet needs to handle:

Method	HTTP Verb	Use Case
doGet()	GET	Retrieve data, display pages
doPost()	POST	Submit forms, create resources
doPut()	PUT	Update/replace a resource
doDelete()	DELETE	Delete a resource
doHead()	HEAD	Like GET but no response body
doOptions()	OPTIONS	Returns supported HTTP methods
doPatch()	PATCH	Partial update (override service())

doGet and doPost

package com.example;

import javax.servlet.*;
import javax.servlet.http.*;
import javax.servlet.annotation.WebServlet;
import java.io.*;

@WebServlet("/form")
public class FormServlet extends HttpServlet {

    // GET: Show the form
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        resp.setContentType("text/html;charset=UTF-8");
        PrintWriter out = resp.getWriter();
        out.println("<!DOCTYPE html><html><body>");
        out.println("<h2>Registration Form</h2>");
        out.println("<form method='post' action='/form'>");
        out.println("  Name: <input type='text' name='name'/><br/>");
        out.println("  Email: <input type='email' name='email'/><br/>");
        out.println("  <button type='submit'>Register</button>");
        out.println("</form></body></html>");
    }

    // POST: Process the form
    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        req.setCharacterEncoding("UTF-8");
        String name  = req.getParameter("name");
        String email = req.getParameter("email");

        // Validate
        if (name == null || name.trim().isEmpty()) {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "Name is required");
            return;
        }

        // Process (save to DB, etc.)
        resp.setContentType("text/html;charset=UTF-8");
        PrintWriter out = resp.getWriter();
        out.println("<h2>Registration Successful!</h2>");
        out.println("<p>Name: " + name + "</p>");
        out.println("<p>Email: " + email + "</p>");
    }
}

HTTP Status Codes

Code	Constant	Meaning
200	SC_OK	Success
201	SC_CREATED	Resource created
301	SC_MOVED_PERMANENTLY	Permanent redirect
302	SC_FOUND	Temporary redirect
400	SC_BAD_REQUEST	Invalid request
401	SC_UNAUTHORIZED	Authentication required
403	SC_FORBIDDEN	Access denied
404	SC_NOT_FOUND	Resource not found
500	SC_INTERNAL_SERVER_ERROR	Server error

sendRedirect vs RequestDispatcher.forward

@WebServlet("/redirect-demo")
public class RedirectServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {

        String action = req.getParameter("action");

        if ("redirect".equals(action)) {
            // sendRedirect: client-side redirect (new HTTP request)
            // URL changes in browser, request attributes are lost
            // Can redirect to external URLs
            resp.sendRedirect("https://example.com");
            // OR: resp.sendRedirect(req.getContextPath() + "/home");

        } else if ("forward".equals(action)) {
            // RequestDispatcher.forward: server-side forward (same request)
            // URL does NOT change in browser, request attributes are preserved
            // Can only forward within the same web application
            req.setAttribute("message", "Forwarded from RedirectServlet");
            RequestDispatcher rd = req.getRequestDispatcher("/WEB-INF/views/result.jsp");
            rd.forward(req, resp);

        } else if ("include".equals(action)) {
            // RequestDispatcher.include: includes another resource's output
            // Both servlets contribute to the response
            RequestDispatcher rd = req.getRequestDispatcher("/header.jsp");
            rd.include(req, resp);
            resp.getWriter().println("<p>Main content here</p>");

        } else {
            resp.sendError(HttpServletResponse.SC_BAD_REQUEST, "Unknown action");
        }
    }
}

Detailed Learning Notes for Servlet HTTP Methods GET, POST, PUT, DELETE

When studying Servlet HTTP Methods GET, POST, PUT, DELETE, separate three things: the concept, the syntax, and the situation where it is useful. This prevents the lesson from becoming a list of commands with no practical meaning.

In Servlet, Servlet HTTP Methods GET, POST, PUT, DELETE becomes easier when you build a tiny example first, then increase complexity. Add one realistic input, one invalid or boundary input, and one explanation of why the result changes.

Identify the main problem this topic solves.
Write the smallest possible working example.
Change one input or option and observe the result.
Note the mistake that would break the example.

Servlet HTTP Methods GET POST PUT DELETE Java review example

class ServletHTTPMethodsGETPOSTPUTDELETEReview {
    public static void main(String[] args) {
        String state = "ready";
        System.out.println("Servlet HTTP Methods GET POST PUT DELETE: " + state);
    }
}

Servlet HTTP Methods GET POST PUT DELETE guard example

String value = null;
if (value == null) {
    System.out.println("Servlet HTTP Methods GET POST PUT DELETE: handle the missing value before continuing");
}

Key Takeaways

Explain the purpose of Servlet HTTP Methods GET, POST, PUT, DELETE before memorizing syntax.
Run or trace one small Servlet example and confirm the output.
Test one normal case, one edge case, and one mistake case for Servlet HTTP Methods GET, POST, PUT, DELETE.
Write the rule in your own words after checking the example.
Connect Servlet HTTP Methods GET, POST, PUT, DELETE to a real project scenario instead of treating it as an isolated definition.

Common Mistakes to Avoid

WRONG Memorizing Servlet HTTP Methods GET POST PUT DELETE without the situation where it is useful.

RIGHT Connect Servlet HTTP Methods GET POST PUT DELETE to a concrete Servlet task.

Purpose makes syntax easier to recall.

WRONG Testing Servlet HTTP Methods GET POST PUT DELETE only with the perfect input.

RIGHT Include empty, missing, duplicate, incompatible, or failed cases when relevant.

Real bugs usually appear outside the perfect path.

WRONG Changing code before reading the visible symptom or error message.

RIGHT Inspect the output, state, configuration, or stack trace connected to Servlet HTTP Methods GET POST PUT DELETE.

Evidence keeps debugging focused.

WRONG Memorizing Servlet HTTP Methods GET POST PUT DELETE without the situation where it is useful.

RIGHT Connect Servlet HTTP Methods GET POST PUT DELETE to a concrete Servlet task.

Purpose makes syntax easier to recall.

Practice Tasks

Modify the example so it handles a different input or condition.
Write one mistake related to Servlet HTTP Methods GET, POST, PUT, DELETE, then fix it and explain the fix.
Summarize when to use Servlet HTTP Methods GET, POST, PUT, DELETE and when another approach is better.
Write a small example that uses Servlet HTTP Methods GET POST PUT DELETE in a realistic Servlet scenario.
Change one important value in the Servlet HTTP Methods GET POST PUT DELETE example and predict the result first.

Frequently Asked Questions

What is the most common mistake in Servlet HTTP Methods GET, POST, PUT, DELETE?

The common mistake is memorizing syntax without understanding when the behavior changes or fails.

What should I remember first about Servlet HTTP Methods GET POST PUT DELETE?

Remember the problem it solves in Servlet, then attach the syntax or steps to that problem.

What proves that I understand Servlet HTTP Methods GET POST PUT DELETE?

You can predict the result of a small example, explain a failure case, and choose it over a nearby alternative for a clear reason.

Where do beginners usually get stuck with Servlet HTTP Methods GET POST PUT DELETE?

They often copy the syntax but skip the state, input, dependency, selector, route, type, or configuration that controls the behavior.

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Servlet HTTP Methods GET, POST, PUT, DELETE: Tutorial, Examples, FAQs & Interview Tips