Less than 10% of the code has to do with the ostensible purpose of the system; the rest deals with input-output, data validation, data structure maintenance, and other housekeeping.
I was trying to download youtube playlist in mp3 format. When I tried below command, I was getting "ERROR: Signature extraction failed: Traceback (most recent call last)"
Where cityList is a array of cities defined in ts file.
But, when I was runing the code, I was getting "ERROR ReferenceError: is not defined in" Then, did followed below steps from terminal to import jquery in app.module.ts
$ npm i jquery --save
$ npm i @types/jquery -D
and imported 'import * as $ from 'jquery';' in app.module.ts
I had installed old version of node js in my laptop ubuntu OS. to start with angular 4 and CLI, we need version more than "node":">= 8.9.0","npm":">= 5.5.1" but my current version is "node":"4.7.2","npm":"3.5.2".
Below are the steps I followed to upgrade and install node with latest version.
I was trying to import git repo in eclipse. it was imported successfully but when I tried to push changes to upstream, I found 'git: cannot open git-receive-pack' in eclipse. Then I realized, before few days, I had configured SSL cert private key in my eclipse, So to get rid off from this error, below steps I have followed.
If your git
configured with SSL cert or it is outdated, We are getting such an
error.
Solution:
Solution1 - From terminal - >
git config http.sslVerify false
Solution2 - If you are using
eclipse, then
open
preferences via application menu Window => Preferences (or on OSX
Eclipse => Settings).
Navigate
to Team => Git => Configuration
click Add
entry..., then put http.sslVerify in the key box and false
in the value box.
I Was confused for how we get the address and address calculation done in an array when we get element from array for passing an index. So, any data structure used to achieve this mechanism? is there any mapping in memory or hashing or indexing like used in DB? It is simple, just like mathematical formula. Consider one dim array ARR of N integer(2 byte memory for each element) stored in memory. Now, to find address of ARR[i]: Adddress(ARR[i]) = Base Address + No. Of bytes for each element * (Find index - Lower bound of ARR)
Here, Base Address = starting address of an array in memory No. Of bytes for each element = for integer, it is 2 bytes Find index = which element you are searching in an array Lower bound of ARR = lower bound index of array For Ex. consider integer array int[] ARR = new int[4];
4 things for to get max output from programming 1. Study and try to predict the behavior of the program 2. try to implement the behavior 3. fix it if assuming it is broken 4. then and then look for expert solution
HashMap does not call hashcode when null is passed as key and null Key is handled as special case.
Put Method
HashMap puts null key in bucket 0 and maps null as key to passed value. it does it by linked list data structure it uses internally.
Linked list data structure used by HashMap (a static class in HashMap.java)
staticclassEntry<K,V>implementsMap.Entry<K,V>{final K key;
V value;Entry<K,V> next;finalint hash;}
In Entry class the K is set to null and value mapped to value passed in put method.
Get Method
While in Hashmap get method the checks if key is passed as null. Search Value for null key in bucket 0. Hence there can only be one null key in one hashmap object.
When you put NULL to HashMap there is special check if you are trying to put NULL as key (called putForNullKey()).
It is special case and works not like you are trying to put some object
which is not null, and as you may see it even doesn't go to hash
calculation.
public V put(K key, V value){if(table == EMPTY_TABLE){
inflateTable(threshold);}if(key ==null)return putForNullKey(value);int hash = hash(key);int i = indexFor(hash, table.length);for(Entry<K,V> e = table[i]; e !=null; e = e.next){Object k;if(e.hash == hash &&((k = e.key)== key || key.equals(k))){
V oldValue = e.value;
e.value = value;
e.recordAccess(this);return oldValue;}}
modCount++;
addEntry(hash, key, value, i);returnnull;}private V putForNullKey(V value){for(Entry<K,V> e = table[0]; e !=null; e = e.next){if(e.key ==null){
V oldValue = e.value;
e.value = value;
e.recordAccess(this);return oldValue;}}
modCount++;
addEntry(0,null, value,0);returnnull;}
Spring Integration enables lightweight messaging within Spring-based applications and supports integration with external systems via declarative adapters. Those adapters provide a higher-level of abstraction over Spring's support for remoting, messaging, and scheduling. Spring Integration's primary goal is to provide a simple model for building enterprise integration solutions while maintaining the separation of concerns that is essential for producing maintainable, testable code. Video:
Why RabbitMQ:
Decouple message publisher and consumer
Store the messages
Routing of messages
Monitoring and management of messages
SpringBoot RabbitMQ Diagram
Producer:
In this spring boot module, We will config rabbitMQ details including exchange, queue and we will send message to queue.
Exchange:
We will create one exchange and send message to this exchange.
Routing :
We will create routing key and bind exchange with specific queue with routing key.
Queue:
Here, our message will be stored. Once consumed by consumers, message will be removed from queue.
