2.10ScrollView(滚动条)-UI组件-Android

ScrollView(滚动条)-UI组件-Android
案例

TOC

ScrollView(滚动条)-UI组件-Android

是一个容器,继承FrameLayout

fullScroll()滚动方法：

• 滚动到底部scrollView.fullScroll(ScrollView.FOCUS_DOWN);
• 滚动到顶部scrollView.fullScroll(ScrollView.FOCUS_UP);

隐藏滑块:android:scrollbars="none"

设置滚动速度

继承ScrollView，然后重写一个 public void fling (int velocityY)的方法：
@Override
public void fling(int velocityY) {
    super.fling(velocityY / 2); //速度变为原来的一半
}

注意:ScrollView控件中只能包含一个View或一个ViewGroup

案例

<?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"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_down"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="滚动到底部" />

    <Button
        android:id="@+id/btn_up"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="滚动到顶部" />

    <ScrollView
        android:id="@+id/scrollView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:scrollbars="none"
        android:layout_weight="1">

        <TextView
            android:id="@+id/txt_show"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="" />
<!--: ScrollView控件中只能包含一个View或一个ViewGroup,放多了会崩溃-->
<!--        <TextView-->
<!--            android:layout_width="wrap_content"-->
<!--            android:layout_height="wrap_content"/>-->

    </ScrollView>
</LinearLayout>

import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ScrollView;
import android.widget.TextView;

import androidx.appcompat.app.AppCompatActivity;

public class ScrollViewActivity extends AppCompatActivity implements View.OnClickListener {
    private Button btn_down;
    private Button btn_up;
    private ScrollView scrollView;
    private TextView txt_show;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.scrollview_layout);
        bindViews();
    }


    private void bindViews() {
        btn_down = (Button) findViewById(R.id.btn_down);
        btn_up = (Button) findViewById(R.id.btn_up);
        scrollView = (ScrollView) findViewById(R.id.scrollView);
        txt_show = (TextView) findViewById(R.id.txt_show);
        btn_down.setOnClickListener(this);
        btn_up.setOnClickListener(this);

        StringBuilder sb = new StringBuilder();
        for (int i = 1; i <= 100; i++) {
            sb.append("我是一条文本内容 * " + i + "
");
        }
        txt_show.setText(sb.toString());

    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.btn_down:
                scrollView.fullScroll(ScrollView.FOCUS_DOWN);
                break;
            case R.id.btn_up:
                scrollView.fullScroll(ScrollView.FOCUS_UP);
                break;
        }
    }
}