InputFilter的使用

最新推荐文章于 2022-03-11 10:35:07 发布

原创最新推荐文章于 2022-03-11 10:35:07 发布 · 1.2k 阅读

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本文介绍了一种使用自定义输入过滤器限制Android应用中EditText输入长度的方法。通过实现InputFilter接口并重写filter方法来控制输入内容的最大长度，当输入超过设定长度时会触发提示。

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class TextLengthFilter implements InputFilter {

        private int mMaxLength;
       Toast mToast; 
        public TextLengthFilter(int maxLength) {
            mMaxLength = maxLength;
        }
        
        @Override
        public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) {
            int keep = mMaxLength - (dest.length() - (dend - dstart));
            if (keep <= 0) {
            	if(mToast != null){
            		mToast.cancel();
            		mToast = null;
            	}
            	mToast = Toast.makeText(getApplicationContext(), R.string.event_edit_activity_prompt, Toast.LENGTH_SHORT);
            	mToast.show();
                return "";
            } else if (keep >= end - start) {
                return null; // keep original
            } else {
                keep += start;
                if (Character.isHighSurrogate(source.charAt(keep - 1))) {
                    --keep;
                    if (keep == start) {
                        ToastUtils.showToastShort(R.string.event_edit_activity_prompt, getApplicationContext());
                        return "";
                    }
                }
                ToastUtils.showToastShort(R.string.event_edit_activity_prompt, getApplicationContext());
                return source.subSequence(start, keep);
            }
        }
    }

                TextLengthFilter filter =new TextLengthFilter(100); 
        	mSearchEditText.setFilters(new InputFilter[]{filter});