Android中的小技巧

• Android中ListView等滚动到某个位置失效

//第一种lv.setSelection(position)//第二种lv.smoothScrollToPosition(position)

第一种直接就是选中位置，第二种有滚动动画，但是有时候，滚动效果看不到，解决方式新建一个runnable，如下：

 lv.post(new Runnable() {                    @Override                    public void run() {                        lv.smoothScrollToPosition(position);                    }                });

• 类似的问题，就是使用SwipeRefreshLayout的时候，希望打开页面的时候，SwipeRefreshLayout正在刷新，可是调用SwipeRefreshLayout的setRefreshing(true)无效，主要原因是页面未渲染完成，解决方式就是延迟执行刷新。

srl.post(new Runnable() {            @Override            public void run() {                    srl.setRefreshing(true);            }        });

• EditText限制输入的小数位数
  Android中提供了一个输入过滤器InputFilter,用于过滤用户输入的内容。
  
  • 定义一个类实现InputFilter 接口

public class DoubleInputFilter implements InputFilter {    /**     * 输入框小数的位数  示例保留一位小数     */    private static final int DECIMAL_DIGITS = 2;    /**     * This method is called when the buffer is going to replace the     * range <code>dstart &hellip; dend</code> of <code>dest</code>     * with the new text from the range <code>start &hellip; end</code>     * of <code>source</code>.  Return the CharSequence that you would     * like to have placed there instead, including an empty string     * if appropriate, or <code>null</code> to accept the original     * replacement.  Be careful to not to reject 0-length replacements,     * as this is what happens when you delete text.  Also beware that     * you should not attempt to make any changes to <code>dest</code>     * from this method; you may only examine it for context.     * <p>     * Note: If <var>source</var> is an instance of {@link Spanned} or     * {@link Spannable}, the span objects in the <var>source</var> should be     * copied into the filtered result (i.e. the non-null return value).     * {@link TextUtils#copySpansFrom} can be used for convenience.     *     * @param source     * @param start     * @param end     * @param dest     * @param dstart     * @param dend     */    @Override    public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {        if ("".equals(source.toString())) {            return null;        }        String value = dest.toString();        String[] split = value.split("\\.");        if (split.length > 1) {            String s = split[1];            int i = s.length() + 1 - DECIMAL_DIGITS;            if (i > 0) {                return source.subSequence(start, end - i);            }        }        return null;    }}

• 使用

et.setFilters(new InputFilter[]{new DoubleInputFilter()});

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