android 中如何限制 EditText 最大输入字符数

方法一：

在 xml 文件中设置文本编辑框属性作字符数限制

如：android:maxLength="10" 即限制最大输入字符个数为10

方法二：

在代码中使用InputFilter 进行过滤

//editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(20)}); 即限定最大输入字符数为20

public class TextEditActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);EditText editText = (EditText)findViewById(R.id.entry);editText.setFilters(new InputFilter[]{new InputFilter.LengthFilter(20)});}}

方法三：

利用 TextWatcher 进行监听

package cie.textEdit;import android.text.Editable;import android.text.Selection;import android.text.TextWatcher;import android.widget.EditText;/** 监听输入内容是否超出最大长度，并设置光标位置* */public class MaxLengthWatcher implements TextWatcher {private int maxLen = 0;private EditText editText = null;public MaxLengthWatcher(int maxLen, EditText editText) {this.maxLen = maxLen;this.editText = editText;}public void afterTextChanged(Editable arg0) {// TODO Auto-generated method stub}public void beforeTextChanged(CharSequence arg0, int arg1, int arg2,int arg3) {// TODO Auto-generated method stub}public void onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) {// TODO Auto-generated method stubEditable editable = editText.getText();int len = editable.length();if(len > maxLen){int selEndIndex = Selection.getSelectionEnd(editable);String str = editable.toString();//截取新字符串String newStr = str.substring(0,maxLen);editText.setText(newStr);editable = editText.getText();//新字符串的长度int newLen = editable.length();//旧光标位置超过字符串长度if(selEndIndex > newLen){selEndIndex = editable.length();}//设置新光标所在的位置Selection.setSelection(editable, selEndIndex);}}}

对应的 activity 部分的调用为：

package cie.textEdit;import android.app.Activity;import android.os.Bundle;import android.text.InputFilter;import android.widget.EditText;public class TextEditActivity extends Activity {/** Called when the activity is first created. */@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.main);EditText editText = (EditText) findViewById(R.id.entry);editText.addTextChangedListener(new MaxLengthWatcher(10, editText));}}

限制输入字符数为10个

main.xml 文件

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"><TextViewandroid:id="@+id/label"android:layout_width="fill_parent"android:layout_height="wrap_content"android:text="Type here:"/><EditTextandroid:id="@+id/entry"android:singleLine="true"android:layout_width="fill_parent"android:layout_height="wrap_content"android:background="@android:drawable/editbox_background"android:layout_below="@id/label"/><Buttonandroid:id="@+id/ok"android:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_below="@id/entry"android:layout_alignParentRight="true"android:layout_marginLeft="10dip"android:text="OK" /><Buttonandroid:layout_width="wrap_content"android:layout_height="wrap_content"android:layout_toLeftOf="@id/ok"android:layout_alignTop="@id/ok"android:text="Cancel" /></RelativeLayout>

效果为输入了10个字符后，光标停在末尾