important java programs(collection+file)

(1) Java Program toFind duplicates and unique set Example Input :

an array of String contains :String[] str = new String[] {"alok", "dhoni", "manish", "rajiv", "alok",

"rajiv"}

output :

unique items: [manish, dhoni]

Duplicate items : [alok, rajiv]

SetExampl.java

package com.alok.Uniqueduplicate;

import java.util.HashSet;

import java.util.Set;

public class SetExample

{

public static void main(String[] args)

{

String[] str = new String[]

{"alok", "dhoni", "manish", "rajiv", "alok", "rajiv"};

Set<String> duplicateSet = new HashSet<String>();

Set<String> uniqueSet = new HashSet<String>();

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

{

if(!uniqueSet.add(str[i]))

{

duplicateSet.add(str[i]);

}

}

uniqueSet.removeAll(duplicateSet);

System.out.println("unique items: "+uniqueSet);

System.out.println("Duplicate items : "+ duplicateSet);

}

}

output :

unique items: [manish, dhoni]

Duplicate items : [alok, rajiv]

(2) create an entity class "Product" with following properties

product_id, product_name, product_details, price. Add

some sample data in this product class using collections.

and sort and display create an entity class "Product" with following properties product_id, product_name,

product_details, price. Add some sample data in this product class

using collections. and sort and display :

-->on default by product_id

-->based on product_name or price

-->sort on product_name, if two product_name is same sort on product_details basis.

-->sort on price, if two prices are same consider sorting on product_id basis.

Product.java

package com.test;

import java.util.Comparator;

public class Product implements Comparable<Product>{

private int productId;

private String productName;

private String productDescription;

private double price;

public Product()

{

}

public Product(int productId, String productName, String

productDescription, double price)

{

this.productId = productId;

this.productName = productName;

this.productDescription = productDescription;

this.price = price;

}

public int getProductId()

{

return productId;

}

public void setProductId(int productId)

{

this.productId = productId;

}

public String getProductName()

{

return productName;

}

public void setProductName(String productName)

{

this.productName = productName;

}

public String getProductDescription()

{

return productDescription;

}

public void setProductDescription(String productDescription)

{

this.productDescription = productDescription;

}

public double getPrice()

{

return price;

}

public void setPrice(double price)

{

this.price = price;

}

@Override

public int compareTo(Product p)

{

return this.productId-p.productId;

}

@Override

public String toString()

{

return "price= " + price + ", productDescription= "

+ productDescription + ", productId= " + productId

+ ", productName= " + productName;

}

public static class ProductInnerClass implements Comparator<Product>

{

@Override

public int compare(Product p1, Product p2)

{

int i=Double.compare(p1.getPrice(), p2.getPrice());

if(i==0)

{

return p1.getProductId()-p2.getProductId();

}

return i;

}

}

}

ProductMain.java

package com.alok.entity;

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

import java.util.ArrayList;

import java.util.Collections;

import java.util.Comparator;

import com.alok.client.Product;

public class ProductMain {

public static void main(String[] args) throws NumberFormatException,

IOException {

ArrayList<Product> productList=new ArrayList<Product>();

productList.add(new Product(555, "Monitor", "15 inch", 4000.00));

productList.add(new Product(2222, "Monitor", "17 inch", 5000.00));

productList.add(new Product(3333, "Del", "Laptop", 4000.00));

productList.add(new Product(6666, "Mouse", "Optical Mouse", 200.00));

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

);

int i=1;

while(i<3)

{

System.out.println("1 : Sort by id");

System.out.println("2 : Sort by name");

System.out.println("3 : Sort by price");

int ch=Integer.parseInt(br.readLine());

switch(ch)

{

case 1 : Collections.sort(productList);

System.out.println("Sorted product : ");

for(Product p : productList)

{

System.out.println(p);

}

break;

case 2 :

Collections.sort(productList, new Comparator<Product>()

{

@Override

public int compare(Product p1, Product p2)

{

int i=p1.getProductName().compareToIgnoreCase

(p2.getProductName());

if(i==0)

{

return p1.getProductDescription().

compareToIgnoreCase(p2.getProductDescription());

}

return i;

}

});



{


}

break;

case 3 :

Collections.sort(productList,new Product.ProductInnerClass());



{


}

break;

default : System.out.println("Invalid Option");

System.exit(0);

}

}

}

}

OUTPUT:

1 : Sort by id

2 : Sort by name

3 : Sort by price

1

Sorted product :

price= 4000.0, productDescription= 15 inch, productId= 555,

productName= Monitor



price= 4000.0, productDescription= Laptop, productId= 3333,

productName= Del

price= 200.0, productDescription= Optical Mouse, productId= 6666,

productName= Mouse

1 : Sort by id

2 : Sort by name

3 : Sort by price

2

Sorted product :


productName= Del






productName= Mouse

1 : Sort by id

2 : Sort by name

3 : Sort by price

3

Sorted product :


productName= Mouse




productName= Del



1 : Sort by id

2 : Sort by name

3 : Sort by price

4

Invalid Option

(3) Writte a JAVA program to merge two files by taking

input as two .txt file and Display Files Contents In Third

File sample..

............

input file:

input1.txt

Ram is a good boy

input2.txt

He is Very poor

output file:

output.txt

Ram is a good boy

He is very poor

CombineTwoFile.java

package com.test;


import java.io.BufferedWriter;

import java.io.FileReader;

import java.io.FileWriter;



public class CombineTwoFile

{

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

{

ArrayList<String> list = new ArrayList<String>();

try

{

BufferedReader br = new BufferedReader(new FileReader( "input1.txt"));

BufferedReader r

= new BufferedReader(new FileReader( "input2.txt"));

String s1 =null;

String s2 = null;

while ((s1 = br.readLine()) != null)

{

list.add(s1);

}

while((s2 = r.readLine()) != null)

{

list.add(s2);

}

}

catch (IOException e)

{

e.printStackTrace();

}

BufferedWriter writer=null;

writer = new BufferedWriter(new FileWriter("output.txt"));

String listWord;

for (int i = 0; i< list.size(); i++)

{

listWord = list.get(i);

writer.write(listWord);

writer.write("\n");

}

System.out.println("complited");

writer.close();

}

}

(4) Read a file and count the no of occurance of specific

word

Example Input file

input.txt

class Employee

{

private String name;

public Integer age;

protected Date dob;

public Address addr;

private Date doj;

public String designation;

}

SpecificWordCount.java




import java.util.HashMap;


public class SpecificWordCount

{


{

BufferedReader br=new BufferedReader(new FileReader("input.txt"));

String ch=null;

int count=0;

try

{

HashMap<String, Integer> hmap = new HashMap<String, Integer>();

hmap.put("public", count);

hmap.put("private", count);

hmap.put("protected", count);

while((ch=br.readLine())!=null)

{

String[] word=ch.split(" ");

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

{

if (word[i].equalsIgnoreCase("public"))

{

int value=hmap.get("public");

value++;

hmap.put("public", value);

}

if (word[i].equalsIgnoreCase("private"))

{

int value=hmap.get("private");

value++;

hmap.put("private", value);

}

if (word[i].equalsIgnoreCase("protected"))

{

int value=hmap.get("protected");

value++;

hmap.put("protected", value);

}

}

}

Set<String> keySet=hmap.keySet();

for(String key : keySet)

{

int value=hmap.get(key);

System.out.println(key + "-->" + value);

}

}

catch(Exception e)

{


}

}

output:

protected-->1

public-->3

private-->2

(5) Take a file as input, get the value from file and insert it

in a ArrayList after inserting write all the values of list in

other file...

sample:

Input file: input.txt

class Employee

{


public Integer age;

protected Date dob;


private Date doj;


}

output file: output.txt(Empty file)

InputFile.java

package com.test;


import java.io.BufferedWriter;

import java.io.FileInputStream;

import java.io.FileNotFoundException;

import java.io.FileOutputStream;


import java.io.FileWriter;


import java.io.InputStreamReader;

import java.io.ObjectOutputStream;


public class InputFil

{


{

BufferedReader

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

System.out.println("Enter File Name:");

String fname=br.readLine();

try

{

@SuppressWarnings("unused")

FileInputStream f=new FileInputStream(fname);

System.out.println("*********************************************

********");

System.out.println("content of file are:");

System.out.println("************************");

FileReader file=new FileReader(fname);

BufferedReader b=new BufferedReader(file);

String s1=b.readLine();

while(s1!=null)

{

System.out.println(s1);

s1=b.readLine();

}

}

catch(FileNotFoundException e)

{

System.out.println("File not Found");

return;

}

System.out.println("*************************************************

****");

ArrayList<String>rows = new ArrayList<String>();

try {

System.out.println("*********************************************

********");

System.out.println("In Array List :");

System.out.println("*******************");

BufferedReader r = new BufferedReader(new FileReader(

fname));

String line = null;

while ((line = r.readLine()) != null)

{

String[] arr=line.split("\\s+");

rows.add(line);

}

System.out.println(rows.toString());

} catch (IOException e)

{


}

BufferedWriter writer=null;

writer = new BufferedWriter(new FileWriter("output.txt"));

//ObjectOutputStream out = new ObjectOutputStream((output));

String listWord;

for (int i = 0; i< rows.size(); i++)

{

listWord = rows.get(i);

writer.write(listWord);

writer.write("\n");

}

writer.close();

}

}

output of program

Enter File Name:

input.txt

*****************************************************

content of file are:

************************

class Employee

{


public Integer age;

protected Date dob;


private Date doj;


}

*****************************************************

*****************************************************

In Array List :

*******************

[class Employee, {, private String name;, public Integer age;, protected Date dob;, public

Address addr;, private Date doj;, public String designation;, , }]

open output.txt (we can see all data in input.txt now available in output.txt)

class Employee

{


public Integer age;

protected Date dob;


private Date doj;


}

(6) Java Program To Print Consecutive characters and the

number of times it occurs in ascending order of number

of occurrences

Sample

-----------

input : “I saw a cd player and a modem in ccd”

output : de--> 1

cd --> 2

I saw a player and a mom in c

ContiAlpha.java

package com.test;



import java.util.Collections;

import java.util.HashMap;


public class ContiAlpha

{


{

try

{

HashMap<String, Integer> map= new HashMap<String, Integer>();

String s1="I saw a cd ghplayer and a modem degh in ccd";

s1=s1.toLowerCase();

for(int i=0;i<(s1.length()-1);i++)

{

if(s1.charAt(i+1)-s1.charAt(i)==1)

{

String word=s1.charAt(i)+""+s1.charAt(i+1);

if(map.containsKey(word))

{

int value=map.get(word);

map.put(word,++value);

}

else

{

map.put(word, 1);

}

}

}

ArrayList<ContiSortByValue> list=new ArrayList<ContiSortByValue>();

Set<String> keySet=map.keySet();

String s2=s1;

for(String k : keySet)

{

s2=s2.replace(k, "");

int value=map.get(k);

list.add(new ContiSortByValue(k, value));

}

System.out.println(s2);

Collections.sort(list);

for(ContiSortByValue sort : list)

{

System.out.println(sort);

}

}

catch (Exception e)

{


}

}

}

ContiSortByValue.java

package com.test;

public class ContiSortByValue implements Comparable<ContiSortByValue>

{

private String key;

private Integer value;

public ContiSortByValue()

{

// TODO Auto-generated constructor stub

}

public ContiSortByValue(String key, Integer value)

{

super();

this.key = key;

this.value = value;

}

@Override

public int compareTo(ContiSortByValue obj)

{

return this.value - obj.value;

}

@Override

public String toString()

{

return key + "-->" + value;

}

}

output:

de-->1

cd-->2

i saw a player and a mom in c

important java programs(collection+file)

Technology

product class

public string getproductname

new string

whilei1 public

bufferedreader import

public productint productid

ioexception import

public class setexample