Android Development — Part 4

OnClickListener vs onClick

These two methods have same purpose i.e to user can tap or click to perform an action.But way to implement it is a bit different. android:onClick was added in API level 4 to make it easier, more Javascript-web-like, and drive everything from the XML. What it does internally is add an OnClickListener on the Button, which calls your onClickButton method.

Implementing onCLick event:-

First you need to define in android:onClick="myListener" XML file.Such as in activity_main.xml

<Button
    android:id="@+id/button_id"
    android:layout_width="340dp"
    android:layout_height="56dp"
    android:layout_marginTop="8dp"
    android:onClick="onClickButton"
    android:text="OnClick"
    />

Then define onClickButton method in MainActivity.java.

public void onClickButton(View v){
    //do stuffs
    Toast.makeText(this, "This is onClick Event", Toast.LENGTH_SHORT).show();
}

Implementing OnClickListener event:-

For this define it inside onCreate() Activity

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Button button = (Button) findViewById(R.id.button1);
    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            //do stuffs
            Toast.makeText(MainActivity.this, "This is OnClickListener", Toast.LENGTH_SHORT).show();
        }
    });
}

Toast

In both event inside the function Toast id define. A toast is a simple feedback about an operation in a small popup. It only fills the amount of space required for the message and the current activity remains visible and interactive. Toasts automatically disappear after a timeout.

Toast object looks like this

Toast.makeText(context, text, duration).show();

where

makeText() is a method, with three parameters the application Context, the text message, and the duration for the toast

show() displays toast notification.