android editText 字符长度限制

来源：互联网发布：薛之谦回应风波知乎编辑：程序博客网时间：2024/05/16 18:14

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

publicclass TextEditActivity extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    publicvoid 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)}); 
    } 
} 

public class TextEditActivity extends Activity {    /** Called when the activity is first created. */    @Override    public 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
* */ 
publicclass MaxLengthWatcher implements TextWatcher { 
 
    privateint maxLen = 0; 
    private EditText editText = null; 
     
     
    public MaxLengthWatcher(int maxLen, EditText editText) { 
        this.maxLen = maxLen; 
        this.editText = editText; 
    } 
 
    publicvoid afterTextChanged(Editable arg0) { 
        // TODO Auto-generated method stub 
         
    } 
 
    publicvoid beforeTextChanged(CharSequence arg0, int arg1, int arg2, 
            int arg3) { 
        // TODO Auto-generated method stub 
         
    } 
 
    publicvoid onTextChanged(CharSequence arg0, int arg1, int arg2, int arg3) { 
        // TODO Auto-generated method stub 
        Editable 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); 
             
        } 
    } 
 
} 

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; 
 
publicclass TextEditActivity extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    publicvoid onCreate(Bundle savedInstanceState) { 
        super.onCreate(savedInstanceState); 
        setContentView(R.layout.main); 
 
        EditText editText = (EditText) findViewById(R.id.entry); 
        editText.addTextChangedListener(new MaxLengthWatcher(10, editText)); 
 
    } 
} 

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. */    @Override    public 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

<?xmlversion="1.0"encoding="utf-8"?> 
<RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android" 
    android:layout_width="fill_parent" 
    android:layout_height="fill_parent"> 
    <TextView 
        android:id="@+id/label" 
        android:layout_width="fill_parent" 
        android:layout_height="wrap_content" 
        android:text="Type here:"/> 
    <EditText 
        android: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"/> 
    <Button 
        android: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"/> 
    <Button 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:layout_toLeftOf="@id/ok" 
        android:layout_alignTop="@id/ok" 
        android:text="Cancel"/> 
</RelativeLayout> 

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    android:layout_width="fill_parent"    android:layout_height="fill_parent">    <TextView        android:id="@+id/label"        android:layout_width="fill_parent"        android:layout_height="wrap_content"        android:text="Type here:"/>    <EditText        android: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"/>    <Button        android: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" />    <Button        android: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

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