如果将EditText的输入长度控制为N个字符,那有简单的两种方法:
1.在xml布局文件中对EditText添加 android:maxLength="N";
<EditText android:id="@+id/et_test" android:layout_width="match_parent" android:layout_height="wrap_content" android:maxLength="16" android:layout_centerInParent="true" />
2.也可以在代码中这样写
InputFilter[] filters = { new InputFilter.LengthFilter(16) }; etTest.setFilters(filters);
这样做只能控制字符串长度,但项目中可能会遇到这样的需求,英文字母最多N个,而中文最多N/2个。这样的话直接用LengthFilter就无法实现了,但是我们可以通过自定义InputFilter实现:
package com.example.inputfilterdemo; import java.util.regex.Matcher; import java.util.regex.Pattern; import android.app.Activity; import android.os.Bundle; import android.text.Editable; import android.text.InputFilter; import android.text.Spanned; import android.text.TextWatcher; import android.util.Log; import android.widget.EditText; import android.widget.TextView; import android.widget.Toast; /** * * ClassName:MainActivity * * @author Jerome Song * @version * @since Ver 1.1 * @Date 2013 2013-4-4 下午2:55:42 * * @see */ public class MainActivity extends Activity { private EditText etTest; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); init(); } private void init() { etTest = (EditText) findViewById(R.id.et_test); InputFilter[] filters = { new NameLengthFilter(16) }; etTest.setFilters(filters); } private class NameLengthFilter implements InputFilter { int MAX_EN;// 最大英文/数字长度 一个汉字算两个字母 String regEx = "[\\u4e00-\\u9fa5]"; // unicode编码,判断是否为汉字 public NameLengthFilter(int mAX_EN) { super(); MAX_EN = mAX_EN; } @Override public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) { int destCount = dest.toString().length() + getChineseCount(dest.toString()); int sourceCount = source.toString().length() + getChineseCount(source.toString()); if (destCount + sourceCount > MAX_EN) { Toast.makeText(MainActivity.this, getString(R.string.count), Toast.LENGTH_SHORT).show(); return ""; } else { return source; } } private int getChineseCount(String str) { int count = 0; Pattern p = Pattern.compile(regEx); Matcher m = p.matcher(str); while (m.find()) { for (int i = 0; i <= m.groupCount(); i++) { count = count + 1; } } return count; } } }
demo源码就这样了,有更好的方法或者错的地方希望大家指出,共同进步!