Insprite and modified from CircleIndicator.

Add the JitPack repository to your build.gradle:

repositories {
    maven { url "https://jitpack.io" }
}

Add the dependency:

dependencies {
    compile 'com.github.nekocode:ToolbarIndicator:v1.0'
}

Set the target ViewPager for ToolbarIndicator:

ToolbarIndicator toolbarIndicator = (ToolbarIndicator) this.findViewById(R.id.indicator);
toolbarIndicator.setViewPager(viewPager);

The ToolbarIndicator get titles from FragmentPagerAdapter's getPageTitle function, for more detail you can check about the sample project.