Assignment-13

Multiple users want to read multiple files but when one user read
from a file, others must wait until the reading is finished.
Also print the waiting queue

Source Code:

import java.io.*;
class fileread
{
	void fread(String s1)throws Exception
	{
	String str=s1;
	FileInputStream ob=new FileInputStream(str);
	int x=0;
	do
	{
	x=ob.read();
	Thread.sleep(2);
	}while(x!=-1);
	ob.close();
	}
}

class th1 implements Runnable
{
	public void run()
	{
	try{
	fileread o1=new fileread();
	o1.fread("file1.txt");
	}
	catch(Exception e){}
	}
}

class th2 implements Runnable
{
	public void run()
	{
	try{
	fileread o2=new fileread();
	o2.fread("file2.txt");
	}
	catch(Exception e){}
	}
}


class th3 implements Runnable
{
	public void run()
	{
	try{
	fileread o3=new fileread();
	o3.fread("file3.txt");
	}
	catch(Exception e){}
	}
}

class th4 implements Runnable
{
	public void run()
	{
	try{
	fileread o4=new fileread();
	o4.fread("file4.txt");
	}
	catch(Exception e){}
	}
}

class thmain
{
	public static void main(String ars[])throws Exception
	{
	System.out.print("\nTotal users: User1     User2     User3     User4");
	th1 ob1=new th1();
	th2 ob2=new th2();
	th3 ob3=new th3();
	th4 ob4=new th4();
	Thread t1=new Thread(ob1);
	Thread t2=new Thread(ob2);
	Thread t3=new Thread(ob3);
	Thread t4=new Thread(ob4);
	t1.start();
	t2.start();
	t3.start();
	t4.start();
	
	

while(t1.isAlive() || t2.isAlive() || t3.isAlive())
	{
	if(t1.isAlive())
	{
	int i=0;
	
	if(t1.isAlive() || (t2.isAlive() || t3.isAlive() || 
        t4.isAlive()) && i==0 )
	{
	t2.suspend();
	t3.suspend();
	t4.suspend();
	System.out.print("\n--------------------------------------- 
                          ------------------");
	System.out.print("\nUser1 is reading file");
	System.out.print("\nWaiting queue:");
	if(t2.isAlive())
	System.out.print("     User2");
	if(t3.isAlive())
	System.out.print("     User3");
	if(t4.isAlive())
	System.out.print("     User4");
	
	while(t1.isAlive())
	{
	}
	i=1;
	}
	System.out.print("\nUser1's file reading complete");
	t2.resume();
	t3.resume();
	t4.resume();
	}
	
	if(t2.isAlive())
	{
	int j=0;
	
	if(t2.isAlive() || (t1.isAlive() || t3.isAlive() || 
         t4.isAlive()) && j==0)
	{
	t1.suspend();
	t3.suspend();
	t4.suspend();
	System.out.print("\n---------------------------------------
                         ------------------");
	System.out.print("\nUser2 is reading file");
	System.out.print("\nWaiting queue:");
	if(t1.isAlive())
	System.out.print("     User1");
	if(t3.isAlive())
	System.out.print("     User3");
	if(t4.isAlive())
	System.out.print("     User4");
	while(t2.isAlive())
	{
	}
	j=1;
	}
	System.out.print("\nUser2's file reading complete");
	t1.resume();
	t3.resume();
	t4.resume();
	}

	if(t3.isAlive())
	{
	int k=0;
	if(t3.isAlive() || (t1.isAlive() || t2.isAlive() || 
         t4.isAlive()) && k==0)
	{
	t2.suspend();
	t1.suspend();
	t4.suspend();
	System.out.print("\n---------------------------------------
                          ------------------");
	System.out.print("\nUser3 is reading file");
	System.out.print("\nWaiting queue:");
	if(t1.isAlive())
	System.out.print("     User1");
	if(t2.isAlive())
	System.out.print("     User2");
	if(t4.isAlive())
	System.out.print("     User4");
	while(t3.isAlive())
	{
	}
	k=1;
	}
	System.out.print("\nUser3's file reading complete");
	t2.resume();
	t1.resume();
	t4.resume();
	}

	if(t4.isAlive())
	{
	int m=0;
	
	if(t4.isAlive() || (t1.isAlive() || t3.isAlive() || 
          t2.isAlive()) && m==0)
	{
	t2.suspend();
	t3.suspend();
	t1.suspend();
	System.out.print("\n---------------------------------------
                           ------------------");
	System.out.print("\nUser4 is reading file");
	System.out.print("\nWaiting queue:");
	if(t1.isAlive())
	System.out.print("     User1");
	if(t2.isAlive())
	System.out.print("     User2");
	if(t3.isAlive())
	System.out.print("     User3");
	while(t4.isAlive())
	{
	
	}
	m=1;
	}
	System.out.print("\nUser4's file reading complete");
	t2.resume();
	t3.resume();
	t1.resume();
	}
	}
	t1.join();
	t2.join();
	t3.join();
	t4.join();
	System.out.println("\nExit From file reading");
	}
}


OUTPUT:

D:\Programs>javac newthread.java
Note: newthread.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

D:\Programs>java thmain

Total users: User1     User2     User3     User4
---------------------------------------------------------
User1 is reading file
Waiting queue:     User2     User3     User4
User1's file reading complete
---------------------------------------------------------
User2 is reading file
Waiting queue:     User3     User4
User2's file reading complete
---------------------------------------------------------
User3 is reading file
Waiting queue:     User4
User3's file reading complete
---------------------------------------------------------
User4 is reading file
Waiting queue:
User4's file reading complete
Exit From file reading