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)

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