l RESULT l EXPLANATION 1. designate the id on xml file android:id="@+id/tvInput" 2. enroll the id on kotlin file 1) import import android.widget.Button import android.widget.TextView 2) define the value private var tvInput : TextView? = null 2) initialize the value using find view by 더보기 id + r. id. + (name of id) tvInput = findViewById(R.id.tvInput) 3. use the value on the method 1) set the val..

1. define the color name with colors.xml 1) res>> values >> colors.xml 2) designate the color #636262 2. change the primary color 1) res>> values> themes> themse.xml 2) i changed purple color into light gray at the primary tag @color/light_gray 3. confirm the result

* what i made * point 1 - same space with margin, weight ratio 2 - have toast pop up message when the button is clicked (using onclick and user defined methods) 3 - color, string enrolling 1. constraint >> linear (google prefers constraint layout) 2. enroll the color resource folder >>> values >>> colors.xml 3. enroll the string res > values > strings.xml the real value MyCalculator_chapter7 233..

1. to show the input value 1) change id click the text item on xml file - assign the value on id or add the id tag 더보기 android:id = "@+id/user-defined ID name" android:id="@+id/tvSelectedDate" 2. Text View 1) import text view on kotlin file import android.widget.TextView 2) assign it into the nullable variable class MainActivity : AppCompatActivity() { var tvSelectedDate : TextView? = null make ..

1. change the name of an app values folder - strings.xml file modify the value inside of the tag

1. relation android:layout_width="match_parent" parent : layout have whole width. android:layout_width="wrap_content" wrap : only needs space around the content have width appropriate for the item. 2.padding android:paddingLeft="20dp" android:paddingRight="20dp" android:paddingTop="10dp" android:paddingBottom="10dp" 3. button bg color / text color 4. dp sp difference should check the ic_launcher..