android - 如何在viewpager中隐藏第一个 fragment 上的上一个按钮和最后一个 fragment 上的下一个按钮？

Question

这是我启动 Circlepageindicator 的 MainActivity。

import android.os.Bundle;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.view.View;
import android.view.Window;
import android.widget.Button;

public class MainActivity extends FragmentActivity {
ViewPager pager;
Button prev,next;
@Override
protected void onCreate(Bundle savedInstanceState) {
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

     MyPagerAdapter adapter=new MyPagerAdapter();
     pager = (ViewPager)findViewById(R.id.view_pager);
     pager.setAdapter(adapter);     
     pager.setCurrentItem(0);

     //Bind the title indicator to the adapter
     CirclePageIndicator titleIndicator = (CirclePageIndicator)findViewById(R.id.titles);
     titleIndicator.setViewPager(pager);


     prev = (Button) findViewById(R.id.prev);   
     prev.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Do something in response to button click
                pager.setCurrentItem(pager.getCurrentItem() - 1);

            }
        });

     next = (Button) findViewById(R.id.next);
     next.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
                // Do something in response to button click
                pager.setCurrentItem(pager.getCurrentItem() + 1);

            }
        });

}

@Override
public void onBackPressed() {
    if (pager.getCurrentItem() == 0) {
        // If the user is currently looking at the first step, allow the system to handle the
        // Back button. This calls finish() on this activity and pops the back stack.
        super.onBackPressed();
    } else {
        // Otherwise, select the previous step.
        pager.setCurrentItem(pager.getCurrentItem() - 1);
    }
}

}

我的 Circlepageindicator 与上一个和下一个按钮配合得很好。但我想隐藏第一个 fragment 上的上一个按钮和最后一个 fragment 上的下一个按钮。这方面的新手。任何建议都被接受。谢谢。

更新:

找到解决方案。

CirclePageIndicator titleIndicator = (CirclePageIndicator)findViewById(R.id.titles);
     titleIndicator.setViewPager(pager);

     titleIndicator.setOnPageChangeListener(new OnPageChangeListener() {

        @Override
        public void onPageSelected(int arg0) {
            // TODO Auto-generated method stub
            if(pager.getCurrentItem() == 0)
            {
                prev.setVisibility(View.GONE);
                next.setVisibility(View.VISIBLE);
            }
            if(pager.getCurrentItem() == 1)
            {
                prev.setVisibility(View.VISIBLE);
                next.setVisibility(View.VISIBLE);
            }
            if(pager.getCurrentItem() == 2)
            {
                prev.setVisibility(View.VISIBLE);
                next.setVisibility(View.GONE);
            }
        }

        @Override
        public void onPageScrolled(int arg0, float arg1, int arg2) {
            // TODO Auto-generated method stub

        }

        @Override
        public void onPageScrollStateChanged(int arg0) {
            // TODO Auto-generated method stub

        }
    });

现在，在滑动和单击按钮时，按钮会在相应页面上显示/隐藏。

Answer 1

在ViewPager的OnPageChangeListener的onPageScrolled方法中 titleIndicator.setOnPageChangeListener(new PagerChangeListener());

class PagerChangeListener implements OnPageChangeListener {
    @Override
            public void onPageScrolled(int arg0, float arg1, int arg2) {

                pageSelected = arg0;

                switch (pageSelected) {
                case 0: {

                    preButton.setVisibility(View.INVISIBLE);
                }

                    break;

                case 2: {

                    nexButton.setVisibility(View.INVISIBLE);
                }

                    break;

                default: {
                    nexButton.setVisibility(View.VISIBLE);
                    preButton.setVisibility(View.VISIBLE);
                }
                    break;
                }

            }
}