---《一周快速上手Kotlin For Android》简介

目前Kotlin已正式成为Android的官方语言，作为Android开发者来说，学习和了解Kotlin也是属于理所当然的事情，兴许你觉得Java对于你来说才是真正的开发”利器”，使用Java你能发挥更高的效率，当然，如果如此你还是可以继续使用Java来开发Android。但对于Kotlin来说，开发Android会变得更简单一些，因为Kotlin其实就是Android开发中的语法糖，采用更简短的代码，描述更多的逻辑而已。开发语言本身就没有对错和最优，每个开发语言被开发出来的时代背景不同，需要解决的主要问题也不同。选择适合你自己的就可以。

BroadcastReceiver工作过程

Java 发送广播：

public class MainActivity extends AppCompatActivity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        Button btn_send = findViewById(R.id.btn_send);        btn_send.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                Intent intent = new Intent();                intent.setAction("ACTION_TEST");                intent.putExtra("VALUE", 123);                sendBroadcast(intent);            }        });    }}复制代码

Kotlin 发送广播：

class MainActivity : AppCompatActivity() {    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_main)        val btn_send = findViewById(R.id.btn_send)        btn_send.setOnClickListener {            val intent = Intent()            intent.action = "ACTION_TEST"            intent.putExtra("VALUE", 123)            sendBroadcast(intent)        }    }}复制代码

Java接收广播：

public class Main2Activity extends AppCompatActivity {    private static final String TAG = "Main2Activity";    private MyReceiver myReceiver;    private IntentFilter intentFilter;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main2);        Log.d(TAG, "onCreate");        myReceiver = new MyReceiver();        intentFilter = new IntentFilter();        intentFilter.addAction("ACTION_TEST");        Intent intent = new Intent(this, MainActivity.class);        startActivity(intent);    }    @Override    protected void onResume() {        super.onResume();        registerReceiver(myReceiver, intentFilter);    }    @Override    protected void onDestroy() {        super.onDestroy();        unregisterReceiver(myReceiver);    }    private class MyReceiver extends BroadcastReceiver {        @Override        public void onReceive(Context context, Intent intent) {            if(intent.getAction().equals("ACTION_TEST")){                int value = intent.getIntExtra("VALUE", 0);                Log.i(TAG, "onReceive value: " + value);            }        }    }}复制代码

Kotlin接收广播：

class Main2Activity : AppCompatActivity() {    private var myReceiver: MyReceiver? = null    private var intentFilter: IntentFilter? = null    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setContentView(R.layout.activity_main2)        Log.d(TAG, "onCreate")        myReceiver = MyReceiver()        intentFilter = IntentFilter()        intentFilter!!.addAction("ACTION_TEST”)        val intent = Intent(this, MainActivity::class.java)        startActivity(intent)    }    override fun onResume() {        super.onResume()        registerReceiver(myReceiver, intentFilter)    }    override fun onDestroy() {        super.onDestroy()        unregisterReceiver(myReceiver)    }    private inner class MyReceiver : BroadcastReceiver() {        override fun onReceive(context: Context, intent: Intent) {            if (intent.action == "ACTION_TEST") {                val value = intent.getIntExtra("VALUE", 0)                Log.i(TAG, "onReceive value: " + value)            }        }    }    companion object {        private val TAG = "Main2Activity"    }}复制代码