Reader & Writer Streams in Advanced Java Programming

import java.io.BufferedReader;

import java.io.FileReader;

public class Main {

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

    String srcFile = "test.txt";

    BufferedReader br = new BufferedReader(new FileReader(srcFile));

    String text = null;

    while ((text = br.readLine()) != null) {

      System.out.println(text);

    }

    br.close();

  }

}

Buffered Input & Output Streams in Advanced Java Programming

import java.io.BufferedInputStream;

import java.io.FileInputStream;

import java.io.IOException;

class BufferedInputStreamDemo

{

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

{

FileInputStream fin = new FileInputStream("text.txt");

BufferedInputStream bin = new BufferedInputStream(fin);

System.out.println("Number of remaining bytes:" + bin.available());

boolean b=bin.markSupported();

if (b)

bin.mark(bin.available());

bin.skip(4);

System.out.println("FileContents :");

// read characters from FileInputStream and

// write them

int ch;

while ((ch=bin.read()) != -1)

System.out.print((char)ch);

// illustrating reset() method

bin.reset();

while ((ch=bin.read()) != -1)

System.out.print((char)ch);

// close the file

fin.close();

}

}

File Input & Output Stream in Advanced Java Programming

import java.io.*;

public class ReadConsole {

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

      InputStreamReader cin = null;

      try {

         cin = new InputStreamReader(System.in);

         System.out.println("Enter characters, 'q' to quit.");

         char c;

         do {

            c = (char) cin.read();

            System.out.print(c);

         } while(c != 'q');

      }finally {

         if (cin != null) {

            cin.close();

         }

      }

   }

}

File Class in Advanced Java Programming

Home	»	Java	»	Advance Java	»	Java File Handling	»	File Class

The file class is used to deal with fiels and files system in Java. The File class helps determine the properties of a class such as the premissions to access the file, date and time when the file was created and directory path for the file. The File class hides the details how information is retrieved from and stored in files. Files can be used as source as well as destination to store the data for a program or the processed information obtained from the output of a program. Various constructors that can be used to create objects of the File class are:

1. File(String directoryPath): The string parameter directory path determines the path name of the file.
2. File(String diectoryPath, String filename): The string paramter directory path determines the path name of the file and the string parameter filename determines the name of the file.
3. File(File dieObj, String filename): The file parameter dirObj determines the File object that specifies the directory and the string parameter filename determines the name of the file.
4. file(URI uriObj): The URI parameter determines the URI object that describes a file.

Various examples of creating the File class objects based on the constructor are:

File file1=new File("/");

File file2=new File("/","autoexec.bat");

File file3=new File("file1","autoexec.bat");



The following program code shows how to obtain various properties of File Object.

/* =========================================================== File Name : FileClassTest.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Twitter ID : https://twitter.com/AdvanceJava Created By : Bintu Chaudhary =========================================================== */ import java.io.*; class FileClassTest { static void parameter(String string1) { System.out.println(string1); } public static void main(String args[]) { File file1=new File("/java/readme"); parameter("File Name: " +file1.getName()); parameter("Path: " +file1.getPath()); parameter("Abs Path: " +file1.getAbsolutePath()); parameter("Parent: " +file1.getParent()); parameter(file1.exists() ? "exists" : "does not exist"); parameter(file1.canWrite() ? "is writeable" : "is not writeable"); parameter(file1.canRead() ? "is readable" : "is not readable"); parameter("is " + (file1.isDirectory() ? "" : "not" + "a dirctory")); parameter("File last modified: " +file1.lastModified()); parameter("File size: " +file1.length() + "Bytes"); } }

The above example uses various methods such as getname to access the name of a file. The getAbsolutePath method determines the absolute path for the file. The exists function determines whether file exists or not. If the exists the function return true value and if the file does not exist the function returns false value and the above code will be stored in the file called FileClassTest.java, which on compilation will crate a class file called FileClassTest.class. Now compiple this file using below commands in the DOS mode:

C:\>jdk1.4\bin>javac FileClassTest.java
C:\>jdk1.4\bin>java FileClassTest

"Output of FileClassTest.class"

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File Handling

Input/Output Streams	I/O Exceptions
File Class	File Input and Output Stream
Data Input and Output Stream	Buffered Input and Output Streams
Reader and Writer Streams	Random Access File

Polygon in Advanced Java Graphics Programming

/* =========================================================== File Name : Polygon.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Polygon" width=300 Height=300> </applet> */ public class Polygon extends Applet { public void paint(Graphics g) { int xpoints[]={30,200,30,200,30}; int ypoints[]={30,30,200,200,30}; int num=5; g.drawPolygon(xpoints,ypoints,num); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Polygon.java
c:\jdk1.4\bin\appletviewer Polygon.java

"Output of Polygon.class"

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Arcs in Advance Java Graphics Programming

/* =========================================================== File Name : Arcs.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Arcs" width=300 Height=300> </applet> */ public class Arcs extends Applet { public void paint(Graphics g) { g.drawArc(10,40,70,70,0,75); g.fillArc(100,40,70,70,0,75); g.drawArc(10,100,70,80,0,175); g.fillArc(100,100,70,90,0,270); g.drawArc(200,80,80,80,0,180); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Arcs.java
c:\jdk1.4\bin\appletviewer Arcs.java

"Output of Arcs.class"

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Circles & Ellipses in Advance Java Graphics Programming

/* =========================================================== File Name : Ellipses.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Ellipses" width=300 Height=300> </applet> */ public class Ellipses extends Applet { public void paint(Graphics g) { g.drawOval(10,10,60,50); g.fillOval(100,10,75,50); g.drawOval(190,10,90,30); g.fillOval(70,90,140,100); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Ellipses.java
c:\jdk1.4\bin\appletviewer Ellipses.java

"Output of Ellipses.class"

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Rectangle in Advance Java Graphics Programming

/* =========================================================== File Name : Rectanlge.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; /* <applet code="Rectanlge" width=300 Height=300> </applet> */ public class Rectanlge extends Applet { public void paint(Graphics g) { g.drawRect(10,10,60,50); g.fillRect(100,100,100,0); g.drawRoundRect(190,10,60,50,15,15); g.fillRoundRect(70,90,140,100,30,40); } }

After this you can comiple your java applet program as shown below:

c:\jdk1.4\bin\javac Rectanlge.java
c:\jdk1.4\bin\appletviewer Rectanlge.java

"Output of Rectangle.class"

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Lines in Advance Java Graphics Programming

//Drawing Lines import java.awt.*; import java.applet.*; /* <applet code="Lines" width=300 Height=250> </applet> */ public class Lines extends Applet { public void paint(Graphics g) { g.drawLine(0,0,100,100); g.drawLine(0,100,100,0); g.drawLine(40,25,250,180); g.drawLine(5,290,80,19); } }
After this you can comiple your java applet program as shown below:

"Output of Lines.class"

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Displaying The Image Object On The Java Applet

In applets, we can display numerical values by first converting them into strings and then using the drawstring() method of Graphics class we can do this easily by calling the valueOf() Method of String class. Let us consider an example:

/* =========================================================== File Name : DisplayImageInApplet.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; public class DisplayImageInApplet extends Applet { Image img; public void init() { img = getImage(getCodeBase(),"Images/Juggler.gif"); } public void paint(Graphics g) { g.drawImage(img,10,20,this); } }

This applet runs using the following HTML file:

<!-- =========================================================== File Name : DisplayImageInApplet.html WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== --> <HTML> <HEAD> <TITLE>Display Image In Applet</TITLE> </HEAD> <BODY> <APPLET Code="DisplayImageInApplet.class" Width=400 Height=300> </APPLET> </BODY> </HTML>
After this you can comiple your java applet program as shown below:

"Output of DisplayImageInApplet.class"

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-     -   HTML File   -   Image

Getting Input from the User in Java Applet

Applets work in graphical environment. Therefore applets treat input as text strings. We must first create an area of the screen in which user can type and edit input items. We can do this by using the TextField class of the applet package. The values of the fields can be given even editer after the creation of input fields. Next step is to retrieve the items from the fields for display of calculations.

For any kinds of computation on the input field, we must convert it to the right form and the resuls again converted back to strings for display.

Let us consider an example
/* =========================================================== File Name : GettingInputfromtheUser.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; public class GettingInputfromtheUser extends Applet { TextField t1, t2; public void init() { t1 = new TextField(10); t2 = new TextField(10); add(t1); add(t2); t1.setText("0"); t2.setText("0"); } public void paint(Graphics g) { int a=0,b=0,c=0; String str1,str2,str; g.drawString("Enter the number in each box",10,50); try { str1=t1.getText(); a=Integer.parseInt(str1); str2=t2.getText(); b=Integer.parseInt(str2); } catch(Exception e) { } c=a+b; str=String.valueOf(c); g.drawString("Sum is",10,15); g.drawString(str,100,75); } }

This applet runs using the following HTML file:

<!-- =========================================================== File Name : GettingInputfromtheUser.html WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== --> <HTML> <HEAD> <TITLE>Getting Input from the User</TITLE> </HEAD> <BODY> <APPLET Code="GettingInputfromtheUser.class" Width=400 Height=300> </APPLET> </BODY> </HTML>

Note :- after comipling this applet program will not calculate the two variables a and b because for this we need event programming...

"Output of GettingInputfromtheUser.class"

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-     -   HTML File

Display Numerical Values in Applet

 In applets, we can display numerical values by first converting them into strings and then using the drawstring() method of Graphics class we can do this easily by calling the valueOf() Method of String class. Let us consider an example:

import java.awt.*; import java.applet.*; public class DisplayNumericalValues extends Applet {     public void paint(Graphics g)     {         int val1 = 10;         int val2 = 20;                 int sum = val1 + val2;         String str_sum = "Sum="+String.valueOf(sum);         g.drawString(str_sum,100,200);     } }

This applet runs using the following HTML file:

<HTML> <HEAD>     <TITLE>Display Numerical Values</TITLE> </HEAD> <BODY>     <APPLET Code="DisplayNumericalValues.class" Width=400 Height=300>     </APPLET> </BODY>     </HTML>

First Applet Program in Java

/* =========================================================== File Name : FirstJavaApplet.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.awt.*; import java.applet.*; public class FirstJavaApplet extends Applet { public void paint(Graphics g) { g.drawString("My First Java Applet Program",100,100); } }

After creating FirstJavaApplet.java file now you need create FirstJavaApplet.html file as shown below:

<!-- =========================================================== File Name : FirstJavaApplet.html WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== --> <HTML> <HEAD> <TITLE>My First Java Applet Program</TITLE> </HEAD> <BODY> <APPLET Code="FirstJavaApplet.class" Width=300 Height=200> </APPLET> </BODY> </HTML>
After this you can comiple your java applet program as shown below:

"Running Applet"

"Output of FirstJavaApplet.class"

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-     -   HTML File
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Creating Package in Java

The listing below shows a package named package1 containing a single class. Class Ademo.

Ademo.java
/* =========================================================== File Name : Ademo.java Package Name : package1 WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ package package1; public class Ademo { public void show() { System.out.println("Display the Class packclass1"); } }
This source file should be named as class Ademo.Java and stored in the subdirectory package1. After compiling this file, a class Ademo.class file will created should be stored in the same subdirectory.

How to compile or make the package use under commands:

after compiling java create a folder named package1 under bin dir....

Now consider the other program as follows:

Test1.java
/* =========================================================== File Name : Test1.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.io.*; import package1.Ademo; class Test1 { public static void main(String args[]) { package1.Ademo obj = new package1.Ademo(); obj.show(); } }

Output

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Ademo	Test1
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Implementing Interface in Java

/* =========================================================== File Name : ImplementingInterface.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.io.*; interface inter //interface define { void show(); } class interclass implements inter // implement the interface { public void show() { System.out.println("Hello Java - Interface"); } } class ImplementingInterface { public static void main(String args[]) { interclass obj = new interclass(); obj.show(); } }

Output of "ImplementingInterface.java"

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Extending Interface in Java

/* =========================================================== File Name : ExtendingInterface.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.io.*; interface inter1 { int a = 100; final static int b = 200; } interface inter2 extends inter1 { void show(); } class interclass implements inter2 { public void show() { int c = a + b; System.out.println("Sum="+c); } } class ExtendingInterface { public static void main(String args[]) { interclass obj = new interclass(); obj.show(); } }

Output of "ExtendingInterface.java"

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Java Vectors

/* =========================================================== File Name : vectorclass.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.io.*; import java.util.*; class vectorclass { public static void main(String args[]) { Vector list = new Vector(); int l = args.length; for (int i=0; i < l; i++) { list.addElement(args[i]); } list.insertElementAt("Bintu",2); int s = list.size(); String larr[]=new String[s]; list.copyInto(larr); System.out.println("List of Elements"); for (int i=0; i < s; i++) { System.out.println(larr[i]); } } }

Output of "VectorClass.java"

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StringBuffer Class in Java

/* =========================================================== File Name : Str_Buffer.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.io.*; class Str_Buffer { public static void main(String args[]) throws Exception { String nm[]={"Bintu","Chaudhary"}; System.out.println("First Name is :" +nm[0]); System.out.println("Last Name is :" +nm[0]); System.out.println("Uppercase :" +nm[0].toUpperCase()); System.out.println("Full Name is :" +nm[0].concat(nm[0])); System.out.println("Extructed Strings is :" +nm[0].substring(2,5)); } }

Output of "Str_Buffer.java"

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Java String and String Methods

/* =========================================================== File Name : Str_StrMethod.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Created By : Bintu Chaudhary =========================================================== */ import java.io.*; class Str_StrMethod { static String n[] = {"Madras","Delhi","Ahmedabad","Bombay"}; public static void main(String args[]) throws Exception { int s = n.length; String t =null; for(int i=0; i < s; i++) { for(int j=i+1; j < s; j++) { if(n[j].compareTo(n[i]) < 0) //compareTo String Method { t = n[i]; n[i] = n[j]; n[j] = t; } } } for(int i=0; i < s; i++) { System.out.println(n[i]); } } }

Output of "Str_StrMethod.java"

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Two Dimensional Array in Java

/* =========================================================== File Name : TwoDimensionalArray.java WebSite : http://javaproglang.blogspot.in/ Facebook : https://www.facebook.com/AdvanceJavaProgramming Twitter : https://twitter.com/AdvanceJava Created By : Bintu Chaudhary =========================================================== */ import java.io.*; class TwoDimensionalArray { public static void main(String args[]) throws Exception { int a[][] = new int[2][3]; int sum = 0; String n; int r,c; System.out.println("Enter the Elements"); BufferedReader obj=new BufferedReader(new InputStreamReader(System.in)); for(r=0;r< 2; r++) { for(c=0; c< 3; c++) { n = obj.readLine(); a[r][c]=Integer.parseInt(n); } } System.out.println("After the Inputting"); for(r=0; r< 2; r++) { for(c=0; c < 3; c++) { System.out.println("\t" +a[r][c]); sum = sum + a[r][c]; } System.out.println("\n"); } System.out.println("Sum="+sum); } }

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