Java interface有多种用法，最常见的就是通过interface传递数据

• 第一种

public interface IData {    void value(String str);}public class ClassA {    public void sendData(IData idata){        idata.value("This is ClassA'value");    }public class Main {    public static void main(String[] args) {        // TODO Auto-generated method stub        ClassA ca = new ClassA();        ca.sendData(new IData() {            @Override            public void value(String str) {                // TODO Auto-generated method stub                System.out.println(str);            }        });    }}

• 第二种

public interface IPositionListener {    void selectedPosition(int postion);}

public class Adapter extends PagerAdapter{        private List<ImageView> viewList;    IPositionListener iPositionListener;    public Adapter(List<ImageView> viewList) {        this.viewList = viewList;    }    @Override    public int getCount() {        return viewList.size();    }    @Override    public boolean isViewFromObject(View view, Object object) {        return view == object;    }    @Override    public Object instantiateItem(ViewGroup container, int position) {    // 实例化        iPositionListener.selectedPosition(position);        container.addView(viewList.get(position));        return viewList.get(position);    }    @Override    public void destroyItem(ViewGroup container, int position, Object object) {    // 销毁        container.removeView(viewList.get(position));    }    public void setOnItemClickListener(IPositionListener iPositionListener) {        this.iPositionListener = iPositionListener;    }}

private void initView() {        viewPager = (ViewPager) findViewById(R.id.viewpager);        for (int i = 0; i< imgs.length; i++){            img = new ImageView(this);            img.setImageResource(imgs[i]);            viewList.add(img);        }        initViewPagerScroll();        Adapter adapter = new Adapter(viewList);        viewPager.setAdapter(adapter);        mHandler.sendEmptyMessage(0x11);        adapter.setOnItemClickListener(new IPositionListener() {            @Override            public void selectedPosition(int postion) {                Toast.makeText(MainActivity.this,"第"+(postion+1)+"张图片",Toast.LENGTH_LONG).show();                PicClick(postion);            }        });    }    private void PicClick(int postion) {        switch (postion){            // TODO        }    }