Java Interfaceの使い方

Java interfaceにはいろいろな使い方がありますが、最も一般的なのはinterfaceを通じてデータを伝えることです.

第1種

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);
            }
        });

    }

}

以上が最も簡単なデータ伝達の使い方です

第2種

public interface IPositionListener {

    void selectedPosition(int postion);
}

public class Adapter extends PagerAdapter{

    private List viewList;

    IPositionListener iPositionListener;

    public Adapter(List 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) {//    
        iPositionListener.selectedPosition(position);
        container.addView(viewList.get(position));
        return viewList.get(position);
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {//   
        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," "+(postion+1)+"   ",Toast.LENGTH_LONG).show();
                PicClick(postion);
            }
        });
    }

    private void PicClick(int postion) {
        switch (postion){
            // TODO
        }
    }