2.直接在主頁中實現，這樣可能會好些，程式碼如下

package com.example.administrator.logopage;

import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.KeyEvent;
import android.view.View;
import android.view.animation.AlphaAnimation;
import android.view.animation.Animation;
import android.widget.LinearLayout;

public class Main2Activity extends Activity {
    LinearLayout linearLayout;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        AlphaAnimation animation=new AlphaAnimation(1.0f,1.0f);
        animation.setDuration(2000);
        linearLayout= (LinearLayout) findViewById(R.id.ll);
        linearLayout.setAnimation(animation);
        animation.setAnimationListener(new Animation.AnimationListener() {
            @Override
            public void onAnimationStart(Animation animation) {
                linearLayout.setVisibility(View.VISIBLE);
            }

            @Override
            public void onAnimationEnd(Animation animation) {
                linearLayout.setVisibility(View.GONE);  //隱藏起來，不需要任何佈局空間
            }

            @Override
            public void onAnimationRepeat(Animation animation) {
                //linearLayout.setVisibility(View.GONE);
            }
        }
        );
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode==KeyEvent.KEYCODE_BACK){
            Intent i= new Intent(Intent.ACTION_MAIN);  //主啟動，不期望接收資料

            i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);       //新的activity棧中開啟，或者已經存在就調到棧前

            i.addCategory(Intent.CATEGORY_HOME);            //新增種類，為裝置首次啟動顯示的頁面

            startActivity(i);
        }
        return super.onKeyDown(keyCode, event);
    }
}