Kotlin - Observer

 Rxjava - 

Observer - Based on data view willl render (react) karega.

trotling -> making stream for execution (Means clicks event fire krege ek particular duration m taki same event again & again call n ho) 

3 Major Component are there -

    1) Observable

    2) Observer

    3) Operator 

class MainActivity : AppCompatActivity() {

    private var TAG:String = "MainActivity"

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        var btn_throttleFirst : Button = findViewById(R.id.btn_throttleFirst)

        btn_throttleFirst.clicks()
            .throttleFirst(15000,TimeUnit.MILLISECONDS)
            .subscribe {
                Log.d(TAG,"throttleFirst duration : 15000 MLS")
        }

        simpleObserver()
    }

    private fun simpleObserver(){
        var list  = listOf<String>("member 1","member 2","member 3")
        val observable = io.reactivex.rxjava3.core.Observable.fromIterable(list)

        observable.subscribe(object : io.reactivex.rxjava3.core.Observer<String>{
            override fun onSubscribe(d: Disposable) {
                Log.d(TAG,"onSubscribe")
            }

            override fun onError(e: Throwable) {
                Log.d(TAG,"onError")
            }

            override fun onComplete() {
                Log.d(TAG,"onComplete")
            }

            override fun onNext(t: String) {
                Log.d(TAG,"onNext")
            }

        })

    }
}

output -

 throttleFirst duration : 15000 MLS

Node-Js (REPL)

 1) Using For Debug JavaScript code & Experiment Code.

    R- READ 

    E- EVAL 

    P- PRINT 

    L- LOOP 

2) Make New File

    type nul > index.js <-|

3) Delete File

    del nul > Filename

4) Express Js - 

        It Will Provide Simple Rest Api's.

5) node install express --save

6) npm init

SwiftUi - Login Page Example

 //

//  ContentView.swift

//  Chapter1

//

//  Created by Kamal Nishad.

//

import SwiftUI

struct ContentView: View {

    @State private var username: String = ""

    @State private var password:String = ""

    

    var body: some View {

        

        VStack{

            

            WelcomeText()

            UserImage()

            

            TextField("Enter Username",text: $username)

                .padding()

                .background(.regularMaterial)

                .cornerRadius(5.0)

                .padding(.bottom, 0)

        

            SecureField("Enter Password",text: $password)

                .padding()

                .background(.regularMaterial)

                .cornerRadius(5.0)

                .padding(.bottom,5)

            

            Text("Login")

                .font(.headline)

                .foregroundColor(.white)

                .padding()

                .frame(width: 150, height: 50)

                .background(Color.green)

                .cornerRadius(15.0)

 

        }

    }

}

struct WelcomeText:View{

    var body: some View{

       return Text("Welcome")

            .font(.largeTitle)

            .fontWeight(.semibold)

            .padding(.bottom,20)

    }

}

struct UserImage : View{

    var body: some View{

        return Image("profile")

            .resizable()

            .aspectRatio(UIImage(named:"profile")!.size,contentMode: .fill)

            .frame(width: 120, height: 120)

            .clipped()

            .cornerRadius(180)

            .padding(.bottom,20)

    }

}

struct ContentView_Previews: PreviewProvider {

    static var previews: some View {

        ContentView()

    }

}

ReactiNative ListView

import { StatusBar } from 'expo-status-bar';

import { useState } from 'react';

import { Button, StyleSheet, Text, View,TextInput,ScrollView, } from 'react-native';

export default function App() {

  const [enteredGoalText, setEnteredGoalText] = useState('');

  const [courseGoals,setCourseGoals] = useState([]);

  function goalInputHandler(enterdText){

    setEnteredGoalText(enterdText);

  };

  function goalAddHandler(){

    setCourseGoals(currentCourseGoal => [

              ...currentCourseGoal,

              enteredGoalText,

            ]);

  };

  return (

    <View style={styles.appContainer}>

        <View style={styles.inputContainer}>

          <TextInput style={styles.textInput}

                     placeholder="Your course is here"

                     onChangeText={goalInputHandler} />

         

          <Button title='Sumbit' onPress={goalAddHandler}/>

        </View>

        <View style={styles.goalsContainer}>

          <ScrollView alwaysBounceVertical={false}>

                  {courseGoals.map((goal)=>

                      <View  key={goal} style={styles.goalItem}>

                        <Text style={styles.goleText}>{goal}</Text>

                      </View>

                    )}

          </ScrollView>

        </View>

    </View>

  );

}

const styles = StyleSheet.create({

    appContainer:{

      flex:1,

      paddingTop:20,

      paddingHorizontal:16,

    },

    inputContainer:{

      flex:1,

      flexDirection:'row',

      justifyContent:'space',

      alignItems:'center',

      padding:24,

      borderBottomWidth:1,

      borderBottomColor:'#cccccc',

      borderPaddingLef:24

    },

    textInput:{

      borderWidth:2,

      borderColor:'#cccccc',

      width:'70%',

      marginRight:8,

      padding:8,

    },

    goalsContainer:{

        flex:4

    },

    goalItem:{

      margin:8,

      padding:8,

      borderRadius:6,

      backgroundColor:'#5e0acc',

      color:'white',

    },

    goleText:{

        color:'white',

    },

    listTxt:{

      paddingLeft:24,

      paddingTop:10

    }

});

Nodejs - Prototype

 prototype = provide ability for adding new methods or class (Example- Inherit)

1) Home.js

var cal = require("./addition");

cal.addition();

console.log(cal.aval)

2) addition.js

module.exports={

    addition:function(){

        console.log("this is addition module");

    },

    aval:20

}

o/p ->

this is addition module

20

Nodejs- Templete String

 var name ="kamal"

var age = "26"

console.log("value of %s and %s",name,age)

//or

console.log("value one: "+name+"value two: "+age)

//now templete string example is...

console.log(`name ${name} age ${age}`)

Nodejs - Class Example

  Class Example

class users{                         ///creteing class

        constructor(name,age){              //declare constructor

            this.name =name;

            this.age=age;

        }

   

        getName(){

            this.email ="dev@gmail.com";

            return this.name;

        }

        getAge(){

            return this.age;

        }

        getEmail(){

            return this.email;

        }

}

///now crete object of class

var user = new users("kamal","26");

console.log(user.getName())

console.log(user.getAge())

console.log(user.getEmail()) ///agar getName() function define ne rhege pahle to undefine k error ayega

OUTPUT

kamal 26 dev@gmail.com