How to change BottomNavigationBarItem icon when selected, Flutter

Question

I am new to Flutter. I have a BottomNavigationBar with 4 items. I want to change icon of the item when pressed. Please help.

This is what I have done so far.

bottomNavigationBar : new BottomNavigationBar(
        currentIndex: index,
        onTap: (int index) {
          setState(() {
            this.index = index;
          }
          );
          _navigateToScreens(index);
        },
        type: BottomNavigationBarType.fixed,
        items: [
          new BottomNavigationBarItem(
              backgroundColor: Colors.white,
              icon: new Image.asset('images/1.0x/icon1.png'),
              title: new Text("Route1", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: new Image.asset('images/1.0x/icon2.png'),
              title: new Text("Route2", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: new Image.asset('images/1.0x/icon3.png'),
              title: new Text("Route3", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),)),
          new BottomNavigationBarItem(
              icon: new Image.asset('images/1.0x/icon4.png'),
              title: new Text("Route4", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),))
        ]);

Answer 1

You can change the icon by checking for the current index is equal to the index of BottomNavigationBarItem index.

Simple example with static index values:

bottomNavigationBar : new BottomNavigationBar(
        currentIndex: index,
        onTap: (int index) {
          setState(() {
            this.index = index;
          }
          );
          _navigateToScreens(index);
        },
        type: BottomNavigationBarType.fixed,
        items: [
          new BottomNavigationBarItem(
              backgroundColor: Colors.white,
              icon: index==0?new Image.asset('images/1.0x/icon1.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route1", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: index==1?new Image.asset('images/1.0x/icon2.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route2", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: index==2?new Image.asset('images/1.0x/icon3.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route3", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),)),
          new BottomNavigationBarItem(
              icon: index==3?new Image.asset('images/1.0x/icon4.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route4", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),))
        ])

Hope that helps!