Activity01.java

package com.yarin.android.Examples_04_20;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.KeyEvent;
import android.view.View;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.ScrollView;
import android.widget.TextView;

public class Activity01 extends Activity {
    private LinearLayout mLayout;
    private ScrollView mScrollView;
    private final Handler mHandler = new Handler();

    /**
     * Called when the activity is first created.
     */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        //����һ�����Բ���
        mLayout = (LinearLayout) findViewById(R.id.layout);
        //����һ��ScrollView����
        mScrollView = (ScrollView) findViewById(R.id.ScrollView01);

        Button button = (Button) findViewById(R.id.Button01);

        button.setOnClickListener(mClickListener);
        //�ı�Ĭ�Ͻ����л�   
        button.setOnKeyListener(mAddButtonKeyListener);
    }

    //Button�¼�����
    //�������ťʱ������һ��TextView��Button
    private Button.OnClickListener mClickListener = new Button.OnClickListener() {
        private int mIndex = 1;

        @Override
        public void onClick(View arg0) {
            // TODO Auto-generated method stub        
            TextView textView = new TextView(Activity01.this);
            textView.setText("Text View " + mIndex);
            LinearLayout.LayoutParams p = new LinearLayout.LayoutParams(
                    LinearLayout.LayoutParams.FILL_PARENT,
                    LinearLayout.LayoutParams.WRAP_CONTENT
            );
            //����һ��TextView�����Բ�����
            mLayout.addView(textView, p);

            Button buttonView = new Button(Activity01.this);
            buttonView.setText("Button " + mIndex++);

            //����һ��Button�����Բ�����
            mLayout.addView(buttonView, p);
            //�ı�Ĭ�Ͻ����л�  
            buttonView.setOnKeyListener(mNewButtonKeyListener);
            //Ͷ��һ����Ϣ���й���   
            mHandler.post(mScrollToBottom);
        }
    };


    private Runnable mScrollToBottom = new Runnable() {
        @Override
        public void run() {
            // TODO Auto-generated method stub   

            int off = mLayout.getMeasuredHeight() - mScrollView.getHeight();
            if (off > 0) {
                mScrollView.scrollTo(0, off);
            }
        }
    };

    //�¼�����
    private View.OnKeyListener mNewButtonKeyListener = new View.OnKeyListener() {
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN &&
                    event.getAction() == KeyEvent.ACTION_DOWN &&
                    v == mLayout.getChildAt(mLayout.getChildCount() - 1)) {
                findViewById(R.id.Button01).requestFocus();
                return true;
            }
            return false;
        }
    };

    //�¼�����
    private View.OnKeyListener mAddButtonKeyListener = new Button.OnKeyListener() {
        @Override
        public boolean onKey(View v, int keyCode, KeyEvent event) {
            // TODO Auto-generated method stub                  
            View viewToFoucus = null;
            if (event.getAction() == KeyEvent.ACTION_DOWN) {
                int iCount = mLayout.getChildCount();
                switch (keyCode) {
                    case KeyEvent.KEYCODE_DPAD_UP:
                        if (iCount > 0) {
                            viewToFoucus = mLayout.getChildAt(iCount - 1);
                        }
                        break;
                    case KeyEvent.KEYCODE_DPAD_DOWN:
                        if (iCount < mLayout.getWeightSum()) {  //TODO
                            viewToFoucus = mLayout.getChildAt(iCount + 1);
                        }
                        break;
                    default:
                        break;
                }
            }
            if (viewToFoucus != null) {
                viewToFoucus.requestFocus();
                return true;
            } else {
                return false;
            }
        }
    };
}