如何在 Kotlin 中声明变量？ 我收到“未解决的参考”

Question

I am getting errors on the lines compiling message_text .

Answer 1

You never "closed" lambda for the start_button click listener. Add a closing curly brace } :

    ...
    text_id.text = "my text"
} // <- this one's missing

Answer 2

you have to declare the variables and you should identify the view by id before using them as below.

    TextView message_text;

    Override fun onCreate(savedInstanceState: Bundle?){

       Super.onCreate(savedInstanceState)
       setContentView(R.layout.activity_main);

        message_text = (TextView) findViewById(R.id.message_text);
        message_text.setText("abc");
    }