{ Android Studio } Explicit Intent & Implicit Intent View binding

Explicit Intent & Implicit Intent View binding

View Binding

1. What is View Binding

   1-1. Before

   • We needed to assign variables such as TextView nameView, phoneView, and addressView … etc

   • We also needed to reference views in xml and then do operations by using findViewById

   • Time consuming and inefficient

   • View Binding is an alternative

   1-2. Changes

   • 3.5 version : we used findViewById

   • 3.6 version : view binding

   • 4.1 version : Kotlin Synthetic; can use id as an variable; only Kotlin supports and NullPointException occurs frequently –> deprecated

   • Current version: Java and Kotlin use view binding only

   1-3. Difference with findViewById

   • View Binding automatically create a class, so we do not need to write id and set types

   • findViewById

     • Null error can occur when a developer use invalid id

     • Cast excepton can occur when a developer made a mistake e.g. textView type <-> imageView type

     • Speed is slower than

2. How to use

   2-1. add gradle

   • Version should be higher than 3.6

   • Higher than 4.0

   android {
   
        ...
   
   
        buildFeatures {
   
   
            viewBinding = true
   
   
        }
   
   }
   
   - 3.6 ~ 4.0
   
   android {
   
        ...
   
   
        viewBinding {
   
   
            enabled true
   
   
        }
   
   }
   

   2-2. activity

   Java

   public class MainActivity extends AppCompatActivity {
   
   private ActivityMainBinding binding;
   
   @Override
   
   protected void onCreate(Bundle savedInstanceState) {
   
        super.onCreate(savedInstanceState);
   
   
        binding = ActivityMainBinding.inflate(getLayoutInflater()); // 1
   
   
        setContentView(binding.getRoot()); // 2
   
   }
   
   private void updateUI(UserProfile userProfile){
   
        binding.name.setText("Hyukjoo Lee"); // 3
   
   
        binding.phone.setText("000-000-0000");
   
   
        binding.address.setText("Burnaby, BC");
   
   }
   

}

1. ActivityMainBinding.inflate(getLayoutInflater()); inflate –> instantiate view in xml

2. Before : R.layout.activity_main After : binding.getRoot() Pass root view we created

3. access properties in the object

rule : ActivityXXXBinding

Kotlin

private lateinit var binding: ActivityMainBinding

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {


        super.onCreate(savedInstanceState)


        binding = ActivityMainBinding.inflate(layoutInflater)


        setContentView(binding.root)



        binding.textView.text = "Hi"
    }

}

In school class: Android Mobile App II

in build.gradle(Module:) script

    android {

         ...


         buildFeatures {


             viewBinding = true


         }

    }

• Build Menu -> Clean Project -> Rebuild Project

this is to ensure binding class is generated

• Import binding class and do some modification

// Source Code
package com.example.converter;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;

import android.widget.EditText;
import android.widget.TextView;

import com.example.converter.databinding.ActivityMainBinding;

import java.util.Locale;

public class MainActivity extends AppCompatActivity {

    private ActivityMainBinding binding; // 1

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // 2
        binding = ActivityMainBinding.inflate(getLayoutInflater());
        View view = binding.getRoot();
        setContentView(view);
    }

    public void convertCurrency(View view) {

        // Traditional ways
//        EditText dollarText = findViewById(R.id.dollarText);
//        TextView textView = findViewById(R.id.textView);

        // dollarText.getText()... => binding.dollarText...
        if(!binding.dollarText.getText().toString().equals("")){
            float dollarValue = Float.parseFloat(binding.dollarText.getText().toString());
            float euroValue = dollarValue * 0.85F ;
            binding.textView.setText(String.format(Locale.ENGLISH, "%.2f", euroValue));
        }
        else {
            binding.textView.setText("No Value");
        }
    }
}