图片轮播：跳出隐藏按钮：点击跳转

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布局：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.shenhuiran_12281.MainActivity">
    <android.support.v4.view.ViewPager
android:id="@+id/viewPager"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true" />
    <RadioGroup
android:id="@+id/radio"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
        <RadioButton
android:id="@+id/btn_01"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:checked="true"/>
        <RadioButton
android:id="@+id/btn_02"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
        <RadioButton
android:id="@+id/btn_03"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
    </RadioGroup>
    <Button
android:id="@+id/btn"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:visibility="gone"
android:layout_above="@id/radio"
android:text="点击" />
</RelativeLayout>

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主要方法：

import android.content.Intent;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.RadioGroup;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends AppCompatActivity {
    private ViewPager viewPager;
    private RadioGroup radio;
    private Button btn;
    private List<Integer> list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        viewPager = findViewById(R.id.viewPager);
        radio = findViewById(R.id.radio);
        btn = findViewById(R.id.btn);
        list = new ArrayList<Integer>();
        list.add(R.drawable.a);
        list.add(R.drawable.b);
        list.add(R.drawable.c);
        MyAdapter adapter = new MyAdapter(list,MainActivity.this);
        viewPager.setAdapter(adapter);
        viewPager.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
            }
            @Override
            public void onPageSelected(int position) {
                switch (position){
                    case 0:
                        radio.check(R.id.btn_01);
                        break;
                    case 1:
                        radio.check(R.id.btn_02);
                        break;
                    case 2:
                        radio.check(R.id.btn_03);
                        btn.setVisibility(View.VISIBLE);
                        break;
                    default:
                        break;
                }
            }
            @Override
            public void onPageScrollStateChanged(int state) {
            }
        });
        btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Intent intent = new Intent(MainActivity.this,Main2Activity.class);
                startActivity(intent);
            }
        });
    }
}

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适配器：MyAdapter 

importandroid.content.Context;
import android.support.v4.view.PagerAdapter;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import java.util.List;
public class MyAdapter extends PagerAdapter{
    private List<Integer> list;
    private Context context;
    public MyAdapter(List<Integer> list, Context context) {
        this.list = list;
        this.context = context;
    }
    @Override
    public int getCount() {
        return list.size();
    }
    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view==object;
    }
    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        ImageView imageView = new ImageView(context);
        imageView.setImageResource(list.get(position));
        imageView.setScaleType(ImageView.ScaleType.FIT_XY);
        container.addView(imageView);
        return imageView;
    }
    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);
    }
}