ScrollView滚动到底部和顶部

ScrollView是Android提供的垂直滑动的组件，HorizontalScrollView与之对应是水平滑动的组件，内部只能包含一个根布局，否则会报错。

报错log

ScrollView中提供了fullScroll来滚动到的位置，有如下4个常用位置：

ScrollView.FOCUS_DOWN;//底部
ScrollView.FOCUS_UP;//顶部
ScrollView.FOCUS_LEFT;//左边
ScrollView.FOCUS_RIGHT;//右边

效果图如下

滚动效果

这里布局文件使用了4个按钮和1个HorizontalScrollView、1个ScrollView，代码如下:

MainActivity代码：

public class MainActivity extends AppCompatActivity {

    private Button down_btn;
    private Button up_btn;
    private Button left_btn;
    private Button right_btn;
    private ScrollView scrollView;
    private LinearLayout rootLl;

    private HorizontalScrollView horizontalScrollView;
    private LinearLayout horizontalRootLl;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
    }

    private void init() {
        down_btn = findViewById(R.id.down_btn);
        up_btn = findViewById(R.id.up_btn);
        left_btn = findViewById(R.id.left_btn);
        right_btn = findViewById(R.id.right_btn);
        scrollView = findViewById(R.id.scrollView);
        horizontalScrollView = findViewById(R.id.horizontalScrollView);
        horizontalRootLl = findViewById(R.id.horizontal_root_ll);
        rootLl = findViewById(R.id.root_ll);
        TextView tv;
        for (int i = 0; i < 100; i++) {
            tv = new TextView(this);
            tv.setText("第" + i + "个");
            rootLl.addView(tv);
        }
        for (int i = 0; i < 100; i++) {
            tv = new TextView(this);
            tv.setText("第" + i + "个");
            horizontalRootLl.addView(tv);
        }
        down_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                scrollView.fullScroll(ScrollView.FOCUS_DOWN);
            }
        });
        up_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                scrollView.fullScroll(ScrollView.FOCUS_UP);
            }
        });
        left_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                horizontalScrollView.fullScroll(ScrollView.FOCUS_LEFT);
            }
        });
        right_btn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                horizontalScrollView.fullScroll(ScrollView.FOCUS_RIGHT);
            }
        });
    }
}