Kotlin-Android之Activity使用详解

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Toast.makeText(this,"ADD",Toast.LENGTH_SHORT).show()
// Toast.makeText(Activity,提醒字符，length_long|short 显示时常长|短)

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classpath "org.jetbrains.kotlin:kotlin-android-extensions:$kotlin_version"

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plugins {
   ...
}
apply plugin: 'kotlin-android-extensions'

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bt1.setOnClickListener{...}

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<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
    <item
        android:id="@+id/Add_item"
        android:title="ADD"/>
    <item
        android:id="@+id/Remove_item"
        android:title="Remove"/>
</menu>

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override fun onCreateOptionsMenu(menu: Menu?): Boolean {
        menuInflater.inflate(R.menu.main,menu) //获取上面写好的资源文件
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        when(item.itemId){
               R.id.Add_item->Toast.makeText(this,"ADD",Toast.LENGTH_SHORT).show()
               R.id.Remove_item->Toast.makeText(this,"REMONE",Toast.LENGTH_SHORT).show()
        }
        return true
    }

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<activity android:name=".IntentMainActivity"> ...</activity>

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//先获取Intent对象，方法（当前的活动，跳转的活动） 
 val intent = Intent(this, IntentMainActivity::class.java)
 //开始跳转
 startActivity(intent)

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<activity android:name=".IntentMainActivity">
            <intent-filter>
                <action android:name="com.example.ACTION_START"/>
                <category android:name="android.intent.category.DEFAULT"/>
                <category android:name="com.example.activity.CATEGORY"/>
            </intent-filter>
</activity>

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val intent = Intent("com.example.ACTION_START")
 intent.addCategory("com.example.activity.CATEGORY")
 startActivity(intent)

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//MainActivity
val intent = Intent(this, IntentMainActivity::class.java)
//向该IntentActivity传输数据,putExtra(name，value)
intent.putExtra("test_data", "显式intent")
startActivity(intent)
//IntentActivity
 //接受上一个activity传输的数据getStringExtra(name)
 val data = intent.getStringExtra("test_data")

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//MainActivity中修改startactivity()为startActivityForResult()
val intent = Intent(this, IntentMainActivity::class.java)
startActivityForResult(intent,1)

//因为使用了startActivityForResult()方法，
//在IntentActivity销毁之后会回调MainActivity的onActivityResult()方法,
//所以我们需要重写onActivityResult来得到返回的数据
override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        when(requestCode){
            1->if (resultCode== RESULT_OK){
                val returnedData= data?.getStringExtra("data_return")
                Log.d("MainActivity","returned data is $returnedData")
            }
        }
    }
    
//IntentActivity中创建一个intent对象来传递数据
 val intent =Intent()
            intent.putExtra("data_return","hello,MainActivity")
            setResult(RESULT_OK,intent)
            finish()

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bt3.setOnClickListener {
            val intent = Intent(Intent.ACTION_VIEW)
            intent.data = Uri.parse("https://www.baidu.com")
            startActivity(intent)

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bt4.setOnClickListener {
            val intent = Intent(Intent.ACTION_DIAL)
            intent.data = Uri.parse("tel:10010")
            startActivity(intent)