Kotlin learning 3: common writing methods of pages

Here is the writing method

Control initialization and click events

        val text: TextView = findViewById(R.id.text);
        text.setOnClickListener {
            Toast.makeText(this, " Click on ", Toast.LENGTH_LONG).show()
        }

Intent Use and value transfer

The first class passes values ：

        val text: TextView = findViewById(R.id.text);
        text.setOnClickListener {
            val myIntent = Intent(this,TwoActivity::class.java)
            myIntent.putExtra("key"," Hello ")
            startActivity(myIntent)
        }

The value of the second class ：

        val value = intent.getStringExtra("key")
        Log.w(" Take the value ", "" + value)

Give the last one activity Return the data

be used  startActivityForResult, first activity Add jump and receive data ：
 

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val text: TextView = findViewById(R.id.text);
        text.setOnClickListener {
            val myIntent = Intent(this, TwoActivity::class.java)
            startActivityForResult(myIntent, 100)
        }

    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        Log.w(" return ", "requestCode:" + requestCode + ";resultCode" + resultCode)
        if (requestCode == 100) {
            if (resultCode == Activity.RESULT_OK) {
                val returnData = data?.getStringExtra("key1")
                Log.w(" Return to get value ", "" + returnData)
            }
        }
    }
}

the second activity Return the data ：

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

        val textTwo: TextView = findViewById(R.id.text);
        textTwo.setOnClickListener {
            val intent = Intent()
            intent.putExtra("key1", " Return value ")
            setResult(Activity.RESULT_OK, intent)
            finish()
        }
    }
}

companion object Use

companion object amount to Java Static method of ：

class MyUtils {
    companion object {
        fun setName(str: String) {
            Log.w("setName call ", "" + str)
        }
    }
}

call ：

MyUtils.setName("111")