Java Practical answers of all the questions but excluded applet questions

Q10.java

package com.suvam;

import java.io.BufferedReader;
import java.io.InputStreamReader;

class Shape{

    public Double length;
    public Double breadth;

    public Shape(Double length, Double breadth){
        this.length = length;
        this.breadth = breadth;
    }

}

class Rect extends Shape{

    public Rect(Double length, Double breadth){
        super(length,breadth);
    }

    public void calcRectArea(){
        System.out.println("Area of rectangle : " + (length * breadth));
    }
}

class Square extends Shape{

    public Square(Double length, Double breadth){
        super(length,breadth);
    }

    public void calcSquareArea(){
        System.out.println("Area of Square : " + (length * length));
    }
}


public class Main {

    public static void main(String[] args) {
        Double length, breadth;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try{
            System.out.println("Enter the sides");
            length = Double.parseDouble(br.readLine());
            breadth = Double.parseDouble(br.readLine());

            Rect r = new Rect(length,breadth);
            Square sq = new Square(length,breadth);

            //calculate rectangle area
            r.calcRectArea();

            //calculate square area
            sq.calcSquareArea();
        }catch (Exception e) {
            e.printStackTrace();
        }


    }
}

Q11.java

package com.suvam;

import java.lang.*;

public class Main {

    public static void main(String[] args) {
	    final String nameArr[][] = {{
	        "Subhash", "10000"
        },{
	        "Gita", "6000"
        },{
	        "Shiyam", "20000"
        }};

	    double salary;

	    for(int i = 0 ; i < nameArr.length ; i++){
            try{
                salary = Double.parseDouble(nameArr[i][1]);
                if(salary <= 10000){
                    System.out.println("employee name : " + nameArr[i][0] + " and salary : " + salary);
                }
                else throw new Exception("Salary is greater than Rs.10000");

            }catch (Exception e){
                System.out.println(e);
            }
        }

    }
}

Q12.java

package com.suvam;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.lang.Exception;
import java.lang.Math;


class MyException extends Exception{

    public MyException(String s){
        super(s);
    }
}

public class Main {

    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        try{
            System.out.println("Enter a number :");
            double num = Double.parseDouble(br.readLine());
            if(num >= 0){
                System.out.format("Sqaure root of %s is : %.2f",num,Math.sqrt(num));
            }else throw new MyException("The number is a negative number");
        }catch (MyException e){
            System.out.println(e);
        }catch (Exception e){
            e.printStackTrace();
        }
}
}

Q13.java

package com.suvam;

public class Main {

    public static void main(String[] args) {
	    StringBuffer firstString = new StringBuffer();
	    StringBuffer secondString = new StringBuffer("12");
	    StringBuffer thirdString = new StringBuffer("Java");

        System.out.println("First string ::");
        System.out.println(firstString);
        System.out.println(firstString.length());
        System.out.println(firstString.capacity());

        System.out.println("Second string ::");
        System.out.println(Integer.parseInt(secondString.toString()));
        System.out.println(secondString.length());
        System.out.println(secondString.capacity());

        System.out.println("Third string ::");
        System.out.println(thirdString);
        System.out.println(thirdString.length());
        System.out.println(thirdString.capacity());
    }
}

Q14.java

package com.suvam;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class Main {

    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        try{
            System.out.println("Enter any string::");
            String anyString  = br.readLine();
            System.out.println("String in lowercase: " + anyString.toLowerCase());
            System.out.println("String in uppercase: " + anyString.toUpperCase());
            System.out.println("Substring from 5 to end: " + anyString.substring(5,anyString.length() - 1));
            System.out.println("Substring from 0 to 5: " + anyString.substring(0,5));
            System.out.println("Substring from 3 to 7: " + anyString.substring(3,7));
            System.out.println("Substring from 5 to 5: " + anyString.substring(5,5));
        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

Q15.java

package com.suvam;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.*;

interface Language{
    final String[] langArr = {"eng","hindi","spanish","greek"};

}

class Library{
    public int bookNo;

    Library(int bookNo){
        this.bookNo = bookNo;
    }
}

class Book extends Library implements Language{
    public String author;
    public String title;

    Book(int bookNo, String author, String title){
        super(bookNo);
        this.author = author;
        this.title = title;
    }
}

class Issue extends Book{


    Issue(int bookNo, String author, String title){
        super(bookNo,author,title);
    }

    void displayBookInfo(String lang){
        System.out.println("Book no: " + bookNo);
        System.out.println("Book title: " + title);
        System.out.println("Author name: " + author);
        if(lang.toLowerCase().startsWith("eng")){
            System.out.println("Book language: " + langArr[0]);
        }else if(lang.toLowerCase().startsWith("hindi")){
            System.out.println("Book language: " + langArr[1]);
        }
        else{
            System.out.println("Book language: unknown");
        }
    }
}

public class Main {

    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int bn;
        String at, ti, lang;
        try{
            System.out.println("Enter bookNo, author name, book title, book language sequentially: ");
            bn = Integer.parseInt(br.readLine());
            at = br.readLine();
            ti = br.readLine();
            lang = br.readLine();

            new Issue(bn,at,ti).displayBookInfo(lang);

        }catch (Exception e){
            e.printStackTrace();
        }
    }
}

Q5.java

package com.suvam;
import java.lang.Thread;

//practical question - create three threads with different priorities

class newThread extends Thread{

    String call;

    newThread(String call){
        this.call = call;
    }
    @Override
    public void run() {
        System.out.println("call: "+ call + " " + getId());
        System.out.println("call: " + call + " " + getName());
        super.run();
    }
}

public class Main {

    public static void main(String[] args) {
        newThread n = new newThread("n");
        newThread n1 = new newThread("n1");
        newThread n2 = new newThread("n2");

        n.setPriority(2);
        n1.setPriority(8);
        n2.setPriority(5);

        n.start();
        n1.start();
        n2.start();
    }
}

Q6.java

import java.lang.Thread;

class Natural{
    public void printNaturalNumber(String threadName){
        try{
            Thread.sleep(2000);
            System.out.println(threadName + "- Natural number : \n");
            for (int i = 1; i < 5; i++){
                System.out.println(i);
            }
        }catch (Exception e){
            System.out.println("Thread interrupted!");
        }
        System.out.println("\n output finished");
    }
}

class NewThread extends Thread{
    private String threadName;
    Natural n;

    NewThread(String threadName, Natural n){
        this.threadName = threadName;
        this.n = n;
    }

    @Override
    public void run() {
        synchronized (n){
            n.printNaturalNumber(threadName);
        }
        super.run();
    }
}

public class Main {
    public static void main(String[] args){
        //creating three threads for displaying the natural nos
        Natural n = new Natural();
        NewThread t1 = new NewThread("first thread", n);
        NewThread t2 = new NewThread("second thread", n);
        NewThread t3 = new NewThread("third thread", n);

        //starting the thread
        t1.start();
        t2.start();
        t3.start();

        //wait threads to end
        try{
            t1.join();
            t2.join();
            t3.join();
        }catch (Exception e){
            System.out.println("Interrupted!");
        }
    }
}

Q7.java

package com.suvam;
import java.lang.Thread;

class DummyThread extends Thread{
    @Override
    public void run() {
        super.run();
    }
}

class ThreadDetails{
    DummyThread t;

    ThreadDetails(DummyThread  d){
        t = d;
    }

    public void displayNameAndPriority(){
        System.out.println("Thread name: " + t.getName());
        System.out.println("Thread priority: " + t.getPriority());
    }

    public void changeThreadName(){
        t.setName("JAVA");
        System.out.println("Thread name changed to : " + t.getName());
    }

    public void displayThreadDetails(){
        System.out.println("Details of thread: ");
        System.out.println("Thread ID: " + t.getId());
        System.out.println("Thread name: " + t.getName());
        System.out.println("Thread priority: " + t.getPriority());
        System.out.println("Thread State: " + t.getState());
    }

}

public class Main {

    public static void main(String[] args) {
	    DummyThread d = new DummyThread();
	    ThreadDetails td = new ThreadDetails(d);

	    //display thread name and it's priority
        td.displayNameAndPriority();
        System.out.println("----------------------");
        //change thread name and display the name
        td.changeThreadName();
        System.out.println("----------------------");
        //display the details of the thread
        td.displayThreadDetails();
        System.out.println("----------------------");
        System.out.println("Over");
    }
}

Q8.java

package com.suvam;

import java.io.BufferedReader;
import java.io.InputStreamReader;


interface CollegeName{
     String collegeName = "LCB college";
}

class Teacher{
    String teacherName;
    String qualification;
}

class Dept extends Teacher implements CollegeName{

    int deptNum;
    String deptName;

    Dept(int deptNum, String deptName, String teacherName, String qualification){
        this.deptNum = deptNum;
        this.deptName = deptName;
        this.teacherName = teacherName;
        this.qualification = qualification;
    }

    void displayDetails(){
        System.out.println("details :");
        System.out.println("Teacher name : " + teacherName);
        System.out.println("Qualification : "  + qualification);
        System.out.println("Department name : " + deptName);
        System.out.println("Department number: " + deptNum);
        System.out.println("College name : " + collegeName);
    }
}

public class Main {

    public static void main(String[] args) {

        BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
        try{
            int dnum = Integer.parseInt(bf.readLine());
            String dname = bf.readLine();
            String tname = bf.readLine();
            String tq = bf.readLine();

            Dept d = new Dept(dnum, dname, tname, tq);

            d.displayDetails();

            bf.close();
        }catch (Exception e){
            e.printStackTrace();
        }

    }
}

Q9.java

package com.suvam;

class Person{
    String name;
    int age;
    String gender;

    public Person(String name, int age, String gender){
        this.name = name;
        this.age = age;
        this.gender = gender;
    }

    public void showData(){
        System.out.println(name + " " + age + " " + gender);
    }
}


class Employee extends Person{
    String name;
    int age;
    String gender;

    public Employee(String n, int a, String g){
        super(n,a,g);
        this.name = n;
        this.age = a;
        this.gender = g;
    }

    public void showData(){
        System.out.println(name + " " + age + " " + gender);
    }
}


class Student extends Person{
    String name;
    int age;
    String gender;

    public Student(String n, int a, String g){
        super(n,a,g);
        this.name = n;
        this.age = a;
        this.gender = g;
    }

    public void showData(){
        System.out.println(name + " " + age + " " + gender);
    }
}

public class Main {

    public static void main(String[] args) {
	    Student s = new Student("Suvam",21,"male");
        Person p = new Person("Raju",22,"male");
        Employee e = new Employee("Kriti",20,"female");
	    p.showData();
	    s.showData();
	    e.showData();
    }
}