Android_Review_8

Intent to Activity or Context 意圖分享純文本， 使用 IntentBuilder 取代 Intent

1. design layout with UI element. And add on Guideline to make a space between ImageView & ImageButton.

   //activity_main.xml
   
   <?xml encoding="utf-8"?>
   
   <layout>
   
       <data>
       
           <variable
              name="price"
              type="Integer"
           />
           
           <variable
               name="volume"
               type="Integer"
           />
           
       </data>
       
       <androidx.constraintlayout.widget.ConstraintLayout
          tools:context=".MainActivity"
       >
       
       <ImageView
         android:id="img"
         android:scaleType="centerCrop"
         android:srcCompat="@drawable/aaa"
       />
       
       <androidx.constraintlayout.widget.Guideline
          android:id="@+id/ggg"
          android:orientation=""
          app:layout_constaintGuide_end="@dimen/default_spacing"
       />
       
       <TextView
          android:id="@+id/price"
       />
       
       <TextView
          android:id="@+id/volume"
       />
       
       <ImageButton
          android:id="imgB"
          android:scaleType="centerCrop"
          tools:src="@drawable/bbb"
       />
       
       </androidx.constraintlayout.widget.ConstraintLayout>
   
   </layout>
   

2. define dimens.

      // go to app/src/main/res/values/dimens.xml
      
      <?xml encoding="utf-8"?>
      
      <resources>
          <dimen name="default_spacing"> 16dp </dimen>
      </resources>
   

3. define customed color.

       // go to app/src/main/res/values/colors.xml
       
       <?xml encoding="utf-8"?>
       
       <resources>
       
          <color name="white">#ffffff</color>
          <color name="green">#6ab343</color>
          <color name="grey">#99000000</color>
          
       </resources>
   

4. define resorces in app/src/main/res/drawable.

5. design menu resource.

   // go to app/src/main/res/menu
   // main_menu.xml
   
   <?xml encoding="utf-8">
   <menu>
      <item
          android:id="@+id/showMenuTouch"
          android:icon="?android:attr/actionModeShareDrawable"
          android:visible="true"
          andrdoid:enable="true"
          android:showAsAction="ifRoom"
      />
   </menu>
   

6. to create a R.string which is located in file called string.xml under dir res/values/.

   <resources>
       <string name="app_name">Kates App</string>
       <string name="dollar_sign">$</string>
       <string name="zero">0</string>
       <string name="garmin">Garmin Watch</string>
       <string name="share_text">I\'ve clicked %1$d Desserts for a total of %2$d$ #AndroidDessertClicker</string>
       <string name="share">Share</string>
       <string name="sharing_not_available">Sharing Not Available</string>
   </resources>
   

7. source line of code.

   package com.example.android.katesapp
   
   [default module]
   import android.os.bundle
   import androidx.appcompat.app.AppCompatActivity
   
   [databind module]
   import androidx.databinding.DataBindingUtil
   import com.example.android.katesapp.databinding.ActivityMainBinding
   
   [intent module]
   import androidx.core.app.ShareCompat
   
   [system error handler module]
   import android.content.ActivityNotFoundException
   
   [menu module]
   import android.view.Menu
   import android.view.MenuItem
   
   [Toast module]
   import android.widget.Toast
   
   class MainActivity: AppCompatActivity(){
   
      
        // 類別中的共用變數
        private var price = 0
        private var volume = 0
        private lateinit var binding: ActivityMainBinding
        
        
        // 製作資料型別
        // data class garminWatchToBuy(val)
        
        // create a Data Type
        // Data Class
        // it includes the resource id.
        data class garmin3C(val imgId: Int, val price: Int, val volumn: Int)
        
        // 建立集合裝載資料型別的成員
        // create a List
        // 拆解集合為成員
        private val allGarmin3C = listOf(
        
           garmin3C(R.drawable.watchA, 6990, 5),
           garmin3C(R.drawable.watchB, 7990, 15),
           garmin3C(R.drawable.watchC, 19900, 20)
        
        
        )
        
        
        // 提取集合中的成員，成員有 id、價格、數量等屬性
        private var currentWatch = allGarmin[0]
   
        override fun onCreate(savedInstanceState: Bundle?){
        
             super.onCreate(savedInstanceState)
             
             // 綁定 UI 元件
             binding = DataBindingUtil.setContentView(this, R.layout.activity_main)
             
             // 顯示 UI 元件
             binding.imgB.setOnClickListner {
                 clickBuyHandler()
             }
             
             binding.imgB.setImageResource(currentWatch.imgId)
             
             binding.price = price
             binding.volumn = volumn
       
             
        }
        
        private fun clickBuyHandler() {
           
           // update value of volumn when user click on the button to demonstrate he/she wanna buy it
           volumnAfterBuy--
           
           binding.volumn = volumnAfterBuy
           
           showOtherWatch()
        
        
        }
        
        private fun showOtherWatch() {
        
             // TODO
             // for-in loop
             // use the data class called allGramin3C
             // retrieve the gramin3C data by creating a varibale calling allGramin3C[0]
             // see Anroid_Review_7
        
        } 
        
        // Menu to be inflated
        override fun onCreateOptionsMenu(menu: Menu): Boolean {
        
           menuInflater.inflate(R.menu.main_menu, menu)
           return super.onCreateOptionsMenu(menu)
           
        }
        
        // Items to be selected
        override fun onOptionsItemSelected(item: MenuItem): Boolean {
        
           // lambda
           // (itemId) -> {body}
           // {itemId -> body}
           when(item.itemId){
               R,id.showMenuTouch -> showGarmin()
           }
           return super.onOptionsItemSelected(item)
        
        }
        
        // ShareCompat is a public class
        // its IntentBuilder is a constructor
        // then call its methods and properties
        // Intent 
        // Exception Handler
        private fun showGarmin() {
        
             // Intent
             // setText(CharSequence text) 
             // Set the literal text data to be sent as part of the share.
             // Question on getIntent() instead of .intent
             
             val showIntent = ShareCompat.IntentBuilder.from(this).setText(getString(R.string.share_text, price, volumn)).setType("text/plain").intent
             
             try {
             
                 startActivity(showIntent)
             
             } catch(ex: ActivityNotFoundException) {
             
                 Toast.makeText(this, getString(), Toast.LENGTH_LONG).show()
             
             }
        
        }
               
   
   }
   

8. today's tip (getString())

   https://cloud.tencent.com/developer/ask/72642

9. today's tip (field)

   %1$d , the first filed that holds integer type variable %2$s , the second field that holds string type varibale

   https://stackoverflow.com/questions/3656371/is-it-possible-dynamically-to-add-string-to-string-xml-in-android

   https://blog.csdn.net/wufen1103/article/details/7846691

10. today's tip (constructor)

    1. constructor can't be called directly.

    2. constructor has no param.

    3. before instance is created, we use constructor instad to ref the members.

    https://stackoverflow.com/questions/4506990/what-is-the-use-of-static-constructors

11. today's tip (CharSequence & String)

    https://stackoverflow.com/questions/3600635/what-is-the-difference-between-charsequence-and-a-string

12. android's tip (IntentBuiler 意圖建構器)

    1. 先導入模組 androidx.core.app.ShareCompat.IntentBuilder。

    2. 我們使用此模組，目的是建造一個 IntentBuilder 的型別的實例。

    3. 因建構子無法單獨使用，故先呼叫公共類別 SharCompat 與建構子 .IntenBuilder。

    4. 建構子成立後，可呼叫內部成員方法，如

       setText(@Nullable text: CharSequence?): IntentBuilder

       setType(@Nullable mimeType: String?): IntentBuilder

       setStream(@Nullable streamUri: Uri?): IntentBuilder

       // HTML markup

       setHtmlText(@Nullable htmlText: String?): IntentBuilder

       ---

       from(@NonNull activity: Activity): IntentBuilder

       startChooser(): void

       getInetent(): Intent

       setSubject(@Nullable subject: String?): IntentBuilder

       setEmailBcc(@Nullable addresses: Array?): IntentBuilder

       setEmailTo(@Nullable addressess: Array?): IntentBuilder

       ---

    https://developer.android.com/reference/kotlin/androidx/core/app/ShareCompat.IntentBuilder

13. android's tip (Intent 意圖)

    ------------Main2Activity.java--------------------

    //使用 putExtra(), getExtra() 夾帶資料

        EditText et;
        et = fincdViewById(R.id.edit_text);
        // et.getText().toString() or getString(et)
        String Msg = et.getString();
        Intent anotherIntent = new Intent(MainActivity.this, Main2Activity.class);
        anotherIntent.putExtra("I luv android since 2018", msg)
        // setResult(2, anotherIntent);
        startActivity(anotherIntent);
    

    ------------MainActivity.java-----------------------

        // onCreate()
        Intent intent = new Intent(MainActivity.this, Main2Activity.class);
        startActivityForResult(intent, 2)
        
        // onActivityResult()
        // if requestCode ==2
        String msg = data.getStringExtra("");
        txv.setText(msg)
    

    https://medium.com/@skywing0527/android自學筆記-14-intent用法-範例練習-ad774d2f92ec