Java 8 Notes Pics

Java 8 , ways to print List

 package com.test;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

public class PrintingList {

public static void main(String[] args) {

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

list.add("System");

list.add("org");

System.out.println("--------using toString() to print list----------");

System.out.println(list);

System.out.println("--------using iterator to print list----------");

Iterator<String> i = list.iterator();

while(i.hasNext())

{

System.out.println(i.next());

}

System.out.println("--------using For loop to print list----------");

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

{

System.out.println(list.get(j));

}

System.out.println("--------using Enhanced For loop to print list----------");

for(String item : list)

{

System.out.println(item);

}

System.out.println("--------using foreach() with lamda to print list----------");

list.forEach(x->System.out.println(x));   

 // Here we are using forEach() or List. it takes Consumer functional Interface as paramer. Consumer Funtional Interface has accept() abstract method. So we are basically implementing accept() in forEach() using lamda expression.

}

}

-----------------------output---------------

--------using toString() to print list----------

[System, org]

--------using iterator to print list----------

System

org

--------using For loop to print list----------

System

org

--------using Enhanced For loop to print list----------

System

org

--------using foreach() with lamda to print list----------

System

org

Permutation

package interview;

public class Permuter
{
public static void main(String[] args)
{
String str = "ABC";
permute(str,0,str.length()-1);
}

private static void permute(String str, int start, int end)
{
if(start==end)
{
System.out.println(str);
return;
}
   for(int i = start;i<=end;i++)
   {
   str = swap(str,start,i);
   permute(str,start+1,end);
   str = swap(str,start,i);  
 
   }

}

private static String swap(String str, int start, int i)
{
    char[] ch = str.toCharArray();
    char temp = ch[start];
    ch[start]= ch[i];
    ch[i] = temp;
    //String str2 = ch.toString();    
return String.valueOf(ch);
}
}

Multithreading:: InterProcess Communication

package multithreading;

public class ThreadA
{
public static void main(String[] args) throws InterruptedException
{
ThreadB b = new ThreadB();
b.start();
synchronized (b)
{
  b.wait();
}
System.out.println("Total: "+ b.sum);
}
}

class ThreadB extends Thread
{
int sum =0;
public void run()
{
for(int i=1;i<100;i++)
{
sum = sum+i;
}
synchronized(this)
{
this.notify();
}
}

}

MultiThreading - Main Thread Wait until Child Thread completes

package multithreading;
//Main Thread Wait until Child Thread completes
public class MyThread5
{


public static void main(String[] args) throws InterruptedException
{
MyThreadJoin mj = new MyThreadJoin();
mj.start();
mj.join(); //-------------------Wait until Child Thread completes

  char[] ch = {'e','t','y','r','w','d','g','h','t','s','e','b','n','l','k'};
  for(char c : ch)
  {
  System.out.println(c);
  try
  {
Thread.sleep(200);
  }
  catch(Exception e)
  {
  System.out.println(e);
  }
  }

}

}

class MyThreadJoin extends Thread
{
public void run()
{
int[] arr = {5,7,8,9,2,3,4,11,33,55,77,55,33,99,100};
for(int a : arr)
{
System.out.println(a);
try
{
Thread.sleep(200);
}
catch(Exception e)
{
System.out.println(e);
}
}
}
}

MultiThreading - Child Thread Wait until Main Thread completes

package multithreading;
//Child Thread Wait until Main Thread completes
public class MyThread6_Join
{

public static void main(String[] args) throws InterruptedException
{
ThreadJoin.mt = Thread.currentThread();
ThreadJoin tj = new ThreadJoin();
tj.start();

  char[] ch = {'e','t','y','r','w','d','g','h','t','s','e','b','n','l','k'};
  for(char c : ch)
  {
  System.out.println(c);
  try
  {
Thread.sleep(200);
  }
  catch(Exception e)
  {
  System.out.println(e);
  }
  }

}

}
//************************************CHILD*********************************
class ThreadJoin extends Thread
{
static Thread mt;
public void run()
{

try
{
mt.join();
}
catch (InterruptedException e1)
{
e1.printStackTrace();
}

int[] arr = {5,7,8,9,2,3,4,11,33,55,77,55,33,99,100};
for(int a : arr)
{
System.out.println(a);
try
{
Thread.sleep(200);
}
catch(Exception e)
{
System.out.println(e);
}
}
}
}