- To set up a click event handler for the linear layout, add this attribute
to the LinearLayout element:
android:onClick="changeBackground"
- Then add an event handler method to the activity file:
// The id of the layout is defined by this
// line already in the linear layout:
android:id="@+id/main"
// Add this line to the linear layout:
android:onClick="changeBackground"
// Add an event handler to the linear layout
// by (1) selecting changeBackground in the
// previous line, (2) enter Alt-Enter, and (3) select
// add click event handler, (4) edit the event
// handler to look like this:
public void changeBackground(View view) {
LinearLayout layout = findViewById(R.id.main);
layout.setBackgroundColor(Color.parseColor("black"));
}
- Add a click event handler for the textview that changes the
text to "Glad to meet you." Answer:
// Add these lines to the textview widget:
android:id="@+id/txt_greeting
android:onClick="respondToGreeting"
// Add this event handler to the activity file
public void respondToGreeting(View view) {
TextView tv = findViewById(R.id.txt_greeting);
tv.setText("Glad to meet you.");
}
- Add a click event handler for the textview that changes the
greeting to uppercase. Answer:
// Add these lines to the textview widget:
android:id="@+id/txt_greeting
android:onClick="respondToGreeting"
// Add this event handler to the activity file
public void changeToUpperCase(View view) {
TextView tv = findViewById(R.id.txt_greeting);
String s = tv.getText( ).toString( );
String t = s.toUpperCase( );
tv.setText(t);
}
