Blog for coders !!: deserialization

Showing posts with label deserialization. Show all posts

Monday, April 30, 2018

Read properties from an xml file !!

Using Properties class:

import java.io.File;
import java.io.FileInputStream;
import java.util.Enumeration;
import java.util.Properties;
public class ReadPropertiesXmlFile {
public static void main(String[] args) throws Exception {
File file = new File("D:\\prop.xml");
FileInputStream fileInput = new FileInputStream(file);
Properties properties = new Properties();
properties.loadFromXML(fileInput);
fileInput.close();
Enumeration enuKeys = properties.keys();
while (enuKeys.hasMoreElements()) {
String key = (String) enuKeys.nextElement();
String value = properties.getProperty(key);
System.out.println(key + ": " + value);
}
}
}

Output:
favoriteSeason: spring
favoriteDay: today
favoriteFruit: apple

prop.xml - file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<comment>Here are some favorites</comment>
<entry key="favoriteSeason">spring</entry>
<entry key="favoriteFruit">apple</entry>
<entry key="favoriteDay">today</entry>

</properties>

Read the data from properties file !!

Using Properties class:

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Enumeration;
import java.util.Properties;
public class ReadPropertiesFiles {
public static void main(String[] args) throws IOException {
File file = new File("D:\\contacts.properties");
FileInputStream fis = new FileInputStream(file);
Properties prop = new Properties();
prop.load(fis);
fis.close();
Enumeration enuKeys = prop.keys();
while (enuKeys.hasMoreElements()) {
String key = (String) enuKeys.nextElement();
String value = prop.getProperty(key);
System.out.println(key + " = " + value);
}
}
}

Output:
delhi = sumit
japan = chet
bangalore = raju
chennai = ishaan

Read file using BufferedReader !!

Using BufferedReader:

import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
public class ReadFileByBufferedReader {
public static void main(String[] args) throws Exception {
File file = new File("D://data.txt");
FileReader fr = new FileReader(file);
BufferedReader br = new BufferedReader(fr);
StringBuffer sb = new StringBuffer();
String line = br.readLine(); // read the line
while (null != line) {
sb.append(line); // append the line
sb.append("\n");
line = br.readLine(); // read the line
}
System.out.println(sb.toString());
fr.close();
}
}

Output:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line

irrespective of amount of data that a file is having.

Read data from a file using BufferedReader !!

Using BufferedReader:

import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
public class ReadFileByBufferedReader {
public static void main(String[] args) {
try {
File file = new File("D://data.txt");
FileReader fr = new FileReader(file);
BufferedReader br = new BufferedReader(fr);
String line = br.readLine(); // read the line
while (null != line) {
System.out.println(line); // print the line
line = br.readLine(); // read the next line
}
fr.close();
} catch (Exception e) {
System.out.println("excepton occured in " + e);
}
}
}

Note: extension support .java/.txt/.xml/.yml/.html/.css etc file

Output:
Hi guys !!
This is Ishaan from India.
and I'm reading the data from a text file line by line using BufferedReader.
Isn't it interesting !! to read the data from a file line by line
irrespective of amount of data that a file is having.

II Approach:

import java.io.File;
import java.io.FileReader;
import java.io.BufferedReader;
public class ReadFileByBufferedReader {
public static void main(String[] args) {
File file = null;
FileReader fr = null;
BufferedReader br = null;
try {
file = new File("D://data.txt");
fr = new FileReader(file);
br = new BufferedReader(fr);
String line = br.readLine(); // read the next line
while (line != null) {
System.out.println(line); // print the line
line = br.readLine(); // read the next line
}
} catch (Exception e) {
System.out.println("excepton occured in " + e);
} finally {
try {
if (fr != null) {
fr.close();
}
if (br != null) {
br.close();
}
} catch (Exception e) {
System.out.println("excepton occured in finally block " + e);
}
}
}
// support .java/.txt/.xml/.yml/.html/.css etc file
}

Sunday, April 29, 2018

Read data from a file using FileReader class !!

Read file using FileReader:

import java.io.File;
import java.io.FileReader;
public class ReadFileByFileReader {
public static void main(String[] args) {
try {
File file = new File("D:\\data.txt");
FileReader fr = new FileReader(file);
int length = (int) file.length();
char c[] = new char[length];
fr.read(c);
String data = new String(c);
System.out.println(data);
fr.close();
} catch (Exception e) {
System.out.println("excepton occured in " + e);
}
}
}

Output:

Hi guys !!

This is Ishaan from India.

and I'm reading the data from a text file line by line using BufferedReader.

Isn't it interesting !! to read the data from a file line by line

irrespective of amount of data that a file is having.

Read / Write data in a file for transient field using ObjectOutputStream

Using ObjectOutputStream class & transient keyword:

import java.io.File;
import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;
class Employee implements Serializable {
private static final long serialVersionUID = 1L;
int id;
String name;
// double salary;
transient double salary;
public Employee(int id, String name, double salary) {
this.id = id;
this.name = name;
this.salary = salary;
}
@Override
public String toString() {
return "[id: " + id + ", name: " + name + ", salary: " + salary + "]";
}
}
public class WriteByObjectOutputStreamExe {
public static void main(String[] args) throws Exception {
File file = new File("D:\\data1.txt");
FileOutputStream fileStream = new FileOutputStream(file);
ObjectOutputStream objStream = new ObjectOutputStream(fileStream);
Employee e1 = new Employee(101, "suresh", 2000);
objStream.writeObject(e1);
objStream.flush();
objStream.close();
}
}

Output:
ͭ sr com.ishaan.filehandling.Employee I idL namet Ljava/lang/String;xp et suresh

Read transient field data from a file using ObjectInputStream:

import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
public class ReadFileByObjectInputStreamExe {
public static void main(String[] args) throws Exception {
File file = new File("D:\\data1.txt");
FileInputStream fileStream = new FileInputStream(file);
ObjectInputStream objStream = new ObjectInputStream(fileStream);
Employee emp = (Employee) objStream.readObject();
System.out.println(emp.toString());
objStream.close();
}
}

Output:
[id: 101, name: suresh, salary: 0.0]

Read file using ObjectInputStream !!

Using ObjectInputStream:

import java.io.File;
import java.io.FileInputStream;
import java.io.ObjectInputStream;
public class ReadFileByObjectInputStreamExe {
public static void main(String[] args) throws Exception {
File file = new File("D:\\data1.txt");
FileInputStream fileStream = new FileInputStream(file);
ObjectInputStream objStream = new ObjectInputStream(fileStream);
Employee emp = (Employee) objStream.readObject();
System.out.println(emp.toString());
objStream.close();
}
}

Employee.java:

import java.io.Serializable;
class Employee implements Serializable {
private static final long serialVersionUID = 1L;
int id;
String name;
double salary;
// transient double salary;
public Employee(int id, String name, double salary) {
this.id = id;
this.name = name;
this.salary = salary;
}
@Override
public String toString() {
return "[id: " + id + ", name: " + name + ", salary: " + salary + "]";
}
}

Output:
[id: 101, name: suresh, salary: 2000.0]

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