button2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            viewPager.setCurrentItem(1, true);
        }
    });


    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            viewPager.setCurrentItem(viewPager.getCurrentItem()-1, true);
        }
    });

button2.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            viewPager.setCurrentItem(1, true);
            button2.setVisibility(View.INVISIBLE);
            button.setVisibility(View.VISIBLE);
        }
    });


    button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            viewPager.setCurrentItem(0, true);
            button.setVisibility(View.INVISIBLE);
            button2.setVisibility(View.VISIBLE);
        }
    });

viewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                @Override
                public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

                }

                @Override
                public void onPageSelected(int position) {
                    if(position==0){
                       button.setVisibility(View.INVISIBLE);
                       button2.setVisibility(View.VISIBLE);
                    } else if(position==1){
                       button2.setVisibility(View.INVISIBLE);
                       button.setVisibility(View.VISIBLE);}
                    }

                @Override
                public void onPageScrollStateChanged(int state) {

                }
            }