Android开发教程viewpager2点击指示标也能切换

viewpager2的使用范例，关键是点击指示标也能切换

一、思路：

用viewpager2加两个imageview

二、效果图：

三、关键代码：

public class MainActivity extends AppCompatActivity {

    private ViewPager2 viewPager2;
    //private SlidingTabLayout stl_title;
    private ImageView iv1;
    private ImageView iv2;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        viewPager2 = findViewById(R.id.viewpager2);
        iv1 = findViewById(R.id.iv1);
        iv2 = findViewById(R.id.iv2);
        //stl_title = findViewById(R.id.stl_title);

        FragmentStateAdapter fragmentStateAdapter = new FragmentStateAdapter(this) {
            @NonNull
            @Override
            public Fragment createFragment(int position) {
                return new CatalogFragment(position);
            }

            @Override
            public int getItemCount() {
                return 2;
            }
        };
        viewPager2.setAdapter(fragmentStateAdapter);
        iv1.setBackgroundColor(Color.RED);
        iv2.setBackgroundColor(Color.parseColor("#eeeeee"));
        viewPager2.registerOnPageChangeCallback(new ViewPager2.OnPageChangeCallback() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                super.onPageScrolled(position, positionOffset, positionOffsetPixels);
            }

            @Override
            public void onPageSelected(int position) {
                super.onPageSelected(position);
                if (position == 0){
                    iv1.setBackgroundColor(Color.RED);
                    iv2.setBackgroundColor(Color.parseColor("#eeeeee"));
                } else {
                    iv2.setBackgroundColor(Color.RED);
                    iv1.setBackgroundColor(Color.parseColor("#eeeeee"));
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {
                super.onPageScrollStateChanged(state);
            }
        });

        iv1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                viewPager2.setCurrentItem(0);
            }
        });

        iv2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                viewPager2.setCurrentItem(1);
            }
        });

//        ArrayList<String> arrayListTitle = new ArrayList<>();
//        arrayListTitle.add("京东1");
//        arrayListTitle.add("京东2");
//        stl_title.setViewPager2(viewPager2, arrayListTitle);
    }
}

四、项目demo源码结构图：

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