Newgen Placement Paper -: Java Questions With Answers

Newgen Previous Years Solved Sample Placement Papers

1. What is the output of the following program?

       public class Question {
       public static void main(String args[]) {
           String s1 = "abc";
           String s2 = "def";
           String s3 = s1.concat(s2.toUpperCase());
           System.out.println(s1 + s2 + s3);
       }
       }
       

   a) abcdefabcdef b) abcabcDEFDEF c) abcdefabcDEF d) None of the above Answer: c) abcdefabcDEF Explanation: The string s3 is formed by concatenating s1 and the uppercase of s2, resulting in "abc" + "def" + "DEF", so the output is "abcdefabcDEF".
2. Which of the following methods are methods of the String class? a) delete( ) b) append( ) c) reverse( ) d) replace( ) Answer: d) replace( ) Explanation: The replace() method is part of the String class, while the others are not.
3. Which of the following methods cause the String object referenced by s to be changed? a) s.concat( ) b) s.toUpperCase( ) c) s.replace( ) d) s.valueOf( ) Answer: a) and b) Explanation: concat() and toUpperCase() return new strings; however, they modify the string indirectly since strings in Java are immutable.
4. Is String a wrapper class? a) True b) False Answer: b) False Explanation: String is not a wrapper class. Wrapper classes in Java are used to wrap primitive types, but String is used to represent sequences of characters.
5. What is an Applet? Should applets have constructors? Answer: Applet is a dynamic and interactive program that runs inside a Web page displayed by a Java-capable browser. We don’t have the concept of Constructors in Applets.
6. How can I arrange for different applets on a web page to communicate with each other? Answer: Name your applets inside the Applet tag and invoke AppletContext’s getApplet() method in your applet code to obtain references to the other applets on the page.
7. How do I select a URL from my Applet and send the browser to that page? Answer: Ask the applet for its applet context and invoke showDocument() on that context object.

       Example:
       URL targetURL;
       String URLString;
       AppletContext context = getAppletContext();
       try {
           targetURL = new URL(URLString);
       } catch (MalformedURLException e) {
           // Code for recovery from the exception
       }
       context.showDocument(targetURL);
       

8. Can applets on different pages communicate with each other? Answer: No. Not directly. The applets will exchange the information at one meeting place, either on the local file system or at a remote system.
9. How do Applets differ from Applications? Answer:
   • Appln: Stand Alone
   • Applet: Needs no explicit installation on the local machine
   • Appln: Execution starts with the main() method
   • Applet: Execution starts with the init() method
   • Appln: May or may not have a GUI
   • Applet: Must run within a GUI (Using AWT)
10. What are the Applet’s Life Cycle methods? Explain them? Answer: init() method - Called when an applet is first loaded. Applets have a defined life cycle including the init(), start(), stop(), and destroy() methods.