学步园

<EditText  android:layout_width = "fill_parent"
    android:layout_height = "wrap_content"
    android:id = "@+id/mEdit"
    android:maxLength = "10"/>

EditText mEdit = (EditText)findViewById(R.id.mEdit);
InputFilter[] filters = {new LengthFilter(10)};
mEdit.setFilters(filters);

EditText mEdit = (EditText)findViewById(R.id.mEdit);    	
InputFilter[] filters = {new AdnNameLengthFilter()};
mEdit.setFilters(filters);
public static class AdnNameLengthFilter implements InputFilter
	{
		private int nMax;

		public  CharSequence filter (CharSequence source, int start, int end, Spanned dest, int dstart, int dend)
		{
			Log.w("Android_12", "source("+start+","+end+")="+source+",dest("+dstart+","+dend+")="+dest);

			if(isChinese(dest.toString())|| isChinese(source.toString()))
			{
				nMax = LENGTH_ZNAME;
			}else
			{
				nMax =LENGTH_ENAME;
			}
			
	            int keep = nMax - (dest.length() - (dend - dstart));

	            if (keep <= 0) {
	                return "";
	            } else if (keep >= end - start) {
	                return null; // keep original
	            } else {
	                return source.subSequence(start, start + keep);
	            }
        
		}
	}

zhuan zi:http://blog.csdn.net/feimor/article/details/6656898

Android 中的EditText最大可输入字符数可以通过xml文件中为EditText设置maxLength属性或者在代码中为EditText设置LengthFilter来设置。

例如要设置EditText只能输入10个字符

xml中：

<EditText  android:layout_width = "fill_parent"
    android:layout_height = "wrap_content"
    android:id = "@+id/mEdit"
    android:maxLength = "10"/>

代码中：

EditText mEdit = (EditText)findViewById(R.id.mEdit);
InputFilter[] filters = {new LengthFilter(10)};
mEdit.setFilters(filters);

以上任意一种方法都可以满足需求，但这种方法只能为EditText设置统一的最大可输入字符，如果碰到根据实际情况限制不同的可输入字符数时，这种方法就不能用了。

比如SIM卡上的电话本姓名字段长度，纯英文下允许输入17个字符，而中文则只可以输入6个字符。此时可以重写InputFilter类来实现。

即：

EditText mEdit = (EditText)findViewById(R.id.mEdit);    	
InputFilter[] filters = {new AdnNameLengthFilter()};
mEdit.setFilters(filters);
public static class AdnNameLengthFilter implements InputFilter
	{
		private int nMax;

		public  CharSequence filter (CharSequence source, int start, int end, Spanned dest, int dstart, int dend)
		{
			Log.w("Android_12", "source("+start+","+end+")="+source+",dest("+dstart+","+dend+")="+dest);

			if(isChinese(dest.toString())|| isChinese(source.toString()))
			{
				nMax = LENGTH_ZNAME;
			}else
			{
				nMax =LENGTH_ENAME;
			}
			
	            int keep = nMax - (dest.length() - (dend - dstart));

	            if (keep <= 0) {
	                return "";
	            } else if (keep >= end - start) {
	                return null; // keep original
	            } else {
	                return source.subSequence(start, start + keep);
	            }
        
		}
	}

其中的isChinese函数是判断是否字符串中是否包含中文字符，具体实现方法就不再赘述了。

LENGTH_ZNAME : 是中文模式下允许输入的最大字符数。

LENGTH_ENAME：是纯英文模式下允许输入的最大字符数。