App启动时的欢迎界面

//其中一种实现方法
public class WelcomeActivity extends AppCompatActivity {
    Handler handler = new Handler();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.welcome_layout);
        handler.postDelayed(new Runnable() {
            @Override
            public void run() {
                Intent intent = new Intent(WelcomeActivity.this,MainActivity.class);
                startActivity(intent);
                finish();
            }
        },3000);
    }
}

布局页里若要使AppCompatImageView控件内容填充屏幕,可加如下属性:

android:scaleType="fitXY"