Android 点击 悬浮穿回到顶部。ScrollView实现

这里 我用ScrollView的scroto(0,0);方法就可以实现。

具体代码如下：

MainActivity.class

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        final ScrollView sv = (ScrollView) findViewById(R.id.sv);
        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                sv.scrollTo(0,0);
            }
        });
    }
}

content_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context=".MainActivity"
    tools:showIn="@layout/activity_main">

    <ScrollView
        android:id="@+id/sv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical">

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">

            <TextView
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Hello World!" />

            <ImageView
                android:layout_width="200dp"
                android:layout_height="300dp"
                android:scaleType="center"
                android:src="@mipmap/ic_launcher" />

            <ImageView
                android:layout_width="200dp"
                android:layout_height="300dp"
                android:scaleType="center"
                android:src="@mipmap/ic_launcher" />

            <ImageView
                android:layout_width="200dp"
                android:layout_height="300dp"
                android:scaleType="center"
                android:src="@mipmap/ic_launcher" />

            <ImageView
                android:layout_width="200dp"
                android:layout_height="300dp"
                android:scaleType="center"
                android:src="@mipmap/ic_launcher" />
        </LinearLayout>
    </ScrollView>


</LinearLayout>