How to draw circle in android by pressing a button?

Question

I want to show small dots on screen while pressing a button, something like pin code...

switch (view.getId()){
    case R.id.buttonNum1:
        editor.putString("PinNumbers",getString(R.string.numberOne));
        int x = 10;
        int y = 30;
        int r = 100;
        Paint mPaint = new Paint();
        mPaint.setColor(Color.BLACK);
        Canvas mCanvas = new Canvas();
        mCanvas.drawCircle(x,y,r,mPaint);
        break;

Answer 1

You can achive by creating ripple effect

create one drawable name like pin_button_ripple in drawable-v21 folder and add bellow code

<ripple xmlns:android="http://schemas.android.com/apk/res/android"
        android:color="?android:colorControlHighlight">
    <item android:id="@android:id/mask">
        <shape android:shape="oval">
            <solid android:color="?android:colorPrimary" />

        </shape>
    </item>
</ripple>

Now in Layout file set it as a background of button and define click listener in activity

 <Button android:id="@+id/btnPinButton" android:layout_width="100dp" android:layout_height="100dp" android:layout_centerInParent="true" android:background="@drawable/pin_button_ripple" android:padding="20dp" android:text="10"/> 

You will see the ripple effect in circle shape like we enter Pin number or password via keyboard and showing that effect