DirList example in java program using file handling

import java.io.*;

class DirList {

      public static void main(String args[]) {

      String dirname="/subha";

      File f1=new File(dirname);

        if(f1.isDirectory()) {

            System.out.println("Directory of " + dirname);

            String s[]=f1.list();

            for(int i=0;i<s.length;i++)

            {

                    File f=new File(dirname + "/" +s[i]);

                    if(f.isDirectory()) {

                            System.out.println(s[i] + " is a Directory");

                    }

            else

             {

                            System.out.println(s[i] + " is a File");

              }

                    }

       }

      else

            {

                         System.out.println(dirname + " is not a directory");

             }

       }

}

Directory of .HTML Files

    // Directory of .HTML Files

        import java.io.*;

        class DirListOnly {

        public static void main(String args[]) {

                String dirname="/subha/html";

                File f1=new File(dirname);

                FilenameFilter only=new OnlyExt("html");

                String s[]=f1.list(only);

                for(int i=0;i<s.length;i++) {

                        System.out.println(s[i]);

                }

             }

        }

FilenameFilter example in java

import java.io.*;

class OnlyExt implements FilenameFilter {

        String ext;

        public OnlyExt(String ext)

       {

        this.ext="."+ ext;

        }

        public boolean accept(File dir,String name)

        {

        return name.endsWith(ext);

        }

}

stack example java program using interface

IntStack.java

interface IntStack {

        void push(int item);

        int pop();

}

FixedStack.java

class FixedStack implements IntStack {

        private int stack[];

        private int tos;

        FixedStack(int size)

        {

        stack=new int[size];

        tos=-1;

        }

        public void push(int item)

        {

        if(tos==stack.length-1)

                System.out.println("stack is full");

        else

                stack[++tos]=item;

        }

        public int pop()

        {

        if(tos<0)

        {

                System.out.println("stack underflow");

                return 0;

        }

        else

                return stack[tos--];

        }

        public static void main(String args[]) {

                FixedStack mystack1=new FixedStack(5);

                FixedStack mystack2=new FixedStack(8);

                for(int i=0;i<6;i++) mystack1.push(i);

                for(int i=0;i<9;i++) mystack2.push(i);

                System.out.println("stack in mystack1");

                for(int i=0;i<6;i++)

                System.out.println(mystack1.pop());

                System.out.println("stack in mystack2");

                for(int i=0;i<9;i++)

                System.out.println(mystack2.pop());

        }

}

interface example java program

Callback.java

interface Callback

{

        public void call(int param);

}

Client.java

class Client implements Callback

{

        public void call(int p)

        {

                System.out.println("Interface Method = " + p);

        }

        public void nonIfaceMeth()

        {

                System.out.println("Non Interface method is also used");

        }

        public static void main(String args[])

        {

                Callback c = new Client();

                c.call(5);

       //         c.nonIfaceMeth();

        }

}

multilevel with constructor example java program

//multilevel with constructor

 class students1

{

        private int sno;

        private String sname;

        students1(int no,String name)

        {

                sno = no;

                sname = name;

        }

        public void dispstud()

        {

                System.out.println("Student No : " + sno);

                System.out.println("Student Name : " + sname);

        }

}

class marks1 extends students1

{

        protected int mark1,mark2;

        marks1(int n1,int n2,int sno,String sname)

        {

                super(sno,sname);

                mark1 = n1;

                mark2 = n2;

        }

        public void dispmarks()

        {

                System.out.println("Mark1 : " + mark1);

                System.out.println("Mark2 : " + mark2);

        }

}

class finaltot1 extends marks1

{

        private int total;

        finaltot1(int n1,int n2,int no,String name)

        {

                super(n1,n2,no,name);

                total = mark1 + mark2;

        }

        public void disptotal()

        {

                System.out.println("Total : " + total);

        }

        public static void main(String args[])

        {

                finaltot1 f = new finaltot1(90,89,100,"Kirthika");

                f.dispstud();

                f.dispmarks();

                f.disptotal();

        }

}

multilevel inheritance example java program

class students

{

        private int sno;

        private String sname;

        public void setstud(int no,String name)

        {

                sno = no;

                sname = name;

        }

        public void putstud()

        {

                System.out.println("Student No : " + sno);

                System.out.println("Student Name : " + sname);

        }

}

class marks extends students

{

        protected int mark1,mark2;

        public void setmarks(int m1,int m2)

        {

                mark1 = m1;

                mark2 = m2;

        }

        public void putmarks()

        {

                System.out.println("Mark1 : " + mark1);

                System.out.println("Mark2 : " + mark2);

        }

}

class finaltot extends marks

{

        private int total;

        public void calc()

        {

                total = mark1 + mark2;

        }

        public void puttotal()

        {

                System.out.println("Total : " + total);

        }

        public static void main(String args[])

        {

                finaltot f = new finaltot();

                f.setstud(100,"Nithya");

                f.setmarks(78,89);

                f.calc();

                f.putstud();

                f.putmarks();

                f.puttotal();

        }

}

single interitance example java program

class emp1

{

        private int eno;

        private String ename;

        emp1(int no,String name)

        {

                System.out.println("Base Constructor");

                eno = no;

                ename=  name;

        }

        public void putemp()

        {

                System.out.println("Empno : " + eno);

                System.out.println("Empname : " + ename);

        }

}

class dept1 extends emp1

{

        private int dno;

        private String dname;

        dept1(int no,String name,int eno,String ename)

        {

                super(eno,ename);

                System.out.println("Derived Constructor");

                dno = no;

                dname = name;

        }

        public void putdept()

        {

                System.out.println("Deptno : " + dno);

                System.out.println("Deptname : " + dname);

        }

        public static void main(String args[])

        {

                dept1 d = new dept1(20,"Sales",100,"Kirthika");

                d.putemp();

                d.putdept();

        }

}

Single inheritance example program

class employee

{

        private int eno;

        private String ename;

        public void setemp(int no,String name)

        {

                eno = no;

                ename = name;

        }

        public void putemp()

        {

                System.out.println("Empno : " + eno);

                System.out.println("Ename : " + ename);

        }

}

class department extends employee

{

        private int dno;

        private String dname;

        public void setdept(int no,String name)

        {

                dno = no;

                dname = name;

        }

        public void putdept()

        {

                System.out.println("Deptno : " + dno);

                System.out.println("Deptname : " + dname);

        }

        public static void main(String args[])

        {

                department d = new department();

                d.setemp(100,"aaaa");

                d.setdept(20,"Sales");

                d.putemp();

                d.putdept();

        }

}

            super () -> Keyword used to call the base constructor;

StringBuffer example

class StringBuf

{

        public static void main(String args[])

        {

                StringBuffer sb = new StringBuffer("Hello World");

                System.out.println(sb + ".capacity() = " + sb.capacity());

                System.out.println(sb + ".length() = " + sb.length());

                System.out.println(sb + ".insert(5,aaa) = " + sb.insert(5,"aaa"));

                System.out.println(sb + ".capacity() = " + sb.capacity());

                System.out.println(sb + ".length() = " + sb.length());

                System.out.println(sb + ".append(bbbb) = " + sb.append("bbbb"));

                System.out.println(sb + ".reverse() = " + sb.reverse());

        }

}

StringMeth examples

class StringMeth

{

        public static void main(String args[])

        {

                String s1 = "This is a sample String";

                String s2 = "    Hello     ";

                String s3 = "Hello World";

                String s4 = "Hello";

                String s5 = "HELLO";

                System.out.println(s1 + ".length() : " + s1.length());

                System.out.println(s1 + ".charAt(2) : " + s1.charAt(2));

                System.out.println("Character Array");

                char c[] = new char[s1.length()+3];

                c[0] = 'a';c[1] = 'b';c[2] = 'c';

                s1.getChars(0,s1.length(),c,2);

                for(int i=0;i<c.length;i++)

                        System.out.print(c[i] + " ");

                System.out.println();

                System.out.println("Byte Array");

                byte b[] = new byte[s3.length()];

                s3.getBytes(0,s3.length(),b,0);

                for(int i=0;i<b.length;i++)

                        System.out.print(b[i] + " ");

                System.out.println();

               System.out.println(s4 + ".compareTo(" + s3 + ") = " +                                                                                            s4.compareTo(s3));

                System.out.println(s3 + ".startsWith(H) = " + s3.startsWith("H"));

                System.out.println(s3 + ".endsWith(u) = " + s3.endsWith("u"));

                System.out.println(s3 + ".indexOf(o) = " + s3.indexOf('o'));

                System.out.println(s3 + ".indexOf(o,5) = " + s3.indexOf('o',5));

                System.out.println(s3 + ".lastIndexOf(o) = " + s3.lastIndexOf('o'));

                System.out.println(s3 + ".lastIndexOf(o,6) = " +                                                                                        s3.lastIndexOf('o',6));

                System.out.println(s3 + ".substring(2,7) = " + s3.substring(2,7));

                System.out.println(s1 + ".concat(s2) = " + s1.concat(s2));

                System.out.println(s4 + ".replace(l,w) = " + s4.replace('l','w'));

                System.out.println(s4 + ".toUpperCase() = " + s4.toUpperCase());

                System.out.println(s5 + ".toLowerCase() = " + s5.toLowerCase());

                System.out.println(s2 + ".trim() = " + s2.trim());

        }

}

String class example

class Strings {

        int i;

        String name[]={"Aswath","Aswin","Anand","Aditya","Anirudh"};

        void show() {

        System.out.println("My favourite names are ");

        for(i=0;i<5;i++) {

                System.out.println(name[i]);

        }

        }

        public static void main(String args[]) {

                Strings s=new Strings();

                s.show();

        }

}

Equal function example program

class equaldemo {

public static void main(String args[]) {

String s1="Hello";

String s2="Hello";

String s3="Good bye";

String s4="HELLO";

System.out.println(s1 + " equals " + s2 + " is " + s1.equals(s2));

System.out.println(s1 + " equals " + s3 + " is " + s1.equals(s3));

System.out.println(s1 + " equals " + s4 + " is " + s1.equals(s4)); 

System.out.println(s1 + " equals " + s4 + " is " + s1.equalsIgnoreCase(s4));

}

}

Hashcode Example

class hash {

public static void main(String args[]) {

        String s1="world";

        String s2="Hello";

System.out.println("The hash code for " + s1 + " is " + s1.hashCode());

System.out.println("The hash code for " + s2 + " is " + s2.hashCode());

}

}

String Example

class Arith {

        String fname="Aswath";

        String lname="Narayanan";

        void show() {

        System.out.println("The fullname is " + fname + " " + lname);

        }

public static void main(String args[]) {

        Arith a1=new Arith();

        a1.show();

}

Addtion program using matrix

class Matrix1

{

        public static void main(String args[]) throws Exception

        {

                int row,col;

                int a[][] = new int[3][3];

                int i,j;

                 BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

                System.out.print("Enter the Row and Column Value : ");

                row = Integer.parseInt(br.readLine());

                col = Integer.parseInt(br.readLine());

               for(i=0;i<row;i++)

                {

                        for(j=0;j<col;j++)

                        {

                                System.out.print("Enter a[" + i + "][" + j + "] : ");

                                a[i][j] = Integer.parseInt(br.readLine());

                        }

                }

                System.out.println("The Given Matrix is ");

                for(i=0;i<row;i++)

                {

                        for(j=0;j<col;j++)

                        {

                                System.out.print(a[i][j] + "\t");

                        }

                        System.out.println();

                }

        }

}

Arrays

import java.io.*;

class Sort

{

        public static void main(String args[]) throws Exception

        {

                int a[] = new int[10];

                int n,i,j,temp;

                BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

                System.out.print("Enter the value of n : ");

                n = Integer.parseInt(br.readLine());

                System.out.println(n);

                for(i=0;i<n;i++)

                {

                        System.out.print("Enter a[" + i + "] : ");

                        a[i] = Integer.parseInt(br.readLine());

                }

                for(i=0;i<n;i++)

                {

                        for(j=i+1;j<n;j++)

                        {

                                if(a[i] > a[j])

                                {

                                        temp = a[i];

                                        a[i] = a[j];

                                        a[j] = temp;

                                }

                        }

                }

                System.out.println("Sorted Values are");

                for(i=0;i<n;i++)

                        System.out.println(a[i]);

        }

}