照着视频教程做的，onTouch能执行，case语句部分也执行到了，两个if语句都没有执行到，为什么？

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <!-- HroizontalScrollView -->
    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/scroll"
        android:scrollbars="none">  <!-- scrollbars="none" 表示隐藏滚动条  -->
        <TextView
            android:textSize="30dp"
            android:id="@+id/content"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </ScrollView>
</LinearLayout>

package com.example.administrator.first;
import android.app.Activity;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ScrollView;
import android.widget.TextView;
public class MainActivity extends Activity {
    TextView tv;
    ScrollView scroll;
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.m1);
        tv = (TextView) findViewById(R.id.content);
        tv.setText(getResources().getString(R.string.content));
        scroll  = (ScrollView) findViewById(R.id.scroll);
        scroll.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent)
            {
                switch(motionEvent.getAction())
                {
                    case MotionEvent.ACTION_MOVE:
                        /*
                        1、getScrollY()--滚动条滑动的距离
                        2、getMeasuredHeight()
                        3、getHeight()
                         */
                        if(scroll.getScaleY()<=0)//顶部状态
                        {
                            Log.i("Main", "滑动到顶部");
                        }
                        //底部状态
                        //TextView的总高度 <= 一屏的高度+ 滚动条的滚动距离
                        if(scroll.getChildAt(0).getMeasuredHeight()<= scroll.getHeight() + scroll.getScaleY())
                        {
                            Log.i("Main", "滑动到底部");
                            Log.i("Main", "(scroll.getChildAt(0).getMeasuredHeight()="+scroll.getChildAt(0).getMeasuredHeight()+
                                    "scroll.getHeight()= "+scroll.getHeight()+
                                    "scroll.getScaleY()=" + scroll.getScaleY());
                        }
                        break;
                }
                return false;
            }
        });
    }
}