【android】EditText输入银行卡号每四位空一格

完美仿微信银行卡号输入，输入每4个数字就自动添加一个空格

代码如下：

import android.text.Editable;import android.text.Selection;import android.text.TextWatcher;import android.widget.EditText;/** * Bank card input TextWatcher * 4 grouping input * Please set EditText max length is 26 * Created by cc_want on 2017/7/13. */public class BankCardTextWatcher implements TextWatcher {    //default max length = 21 + 5 space    private static final int DEFAULT_MAX_LENGTH = 21 + 5;    //max input length    private int maxLength = DEFAULT_MAX_LENGTH;    private int beforeTextLength = 0;    private boolean isChanged = false;    //space count    private int space = 0;    private StringBuffer buffer = new StringBuffer();    private EditText editText;    public static void bind(EditText editText){        new BankCardTextWatcher(editText,DEFAULT_MAX_LENGTH);    }    public static void bind(EditText editText,int maxLength){        new BankCardTextWatcher(editText,maxLength);    }    public BankCardTextWatcher(EditText editText,int maxLength){        this.editText = editText;        this.maxLength = maxLength;        editText.addTextChangedListener(this);    }    @Override    public void beforeTextChanged(CharSequence s, int start, int count, int after) {        beforeTextLength = s.length();        if (buffer.length() > 0) {            buffer.delete(0, buffer.length());        }        space = 0;        for (int i = 0; i < s.length(); i++) {            if (s.charAt(i) == ' ') {                space ++;            }        }    }    @Override    public void onTextChanged(CharSequence s, int start, int before, int count) {        int length = s.length();        buffer.append(s.toString());        if (length == beforeTextLength || length <= 3                || isChanged) {            isChanged = false;            return;        }        isChanged = true;    }    @Override    public void afterTextChanged(Editable s) {        if (isChanged) {            int selectionIndex = editText.getSelectionEnd();            //total char length            int index = 0;            while (index < buffer.length()) {                if (buffer.charAt(index) == ' ') {                    buffer.deleteCharAt(index);                } else {                    index ++;                }            }            //total space count            index = 0;            int totalSpace = 0;            while (index < buffer.length()) {                if ((index == 4 || index == 9 || index == 14 || index == 19 || index == 24)) {                    buffer.insert(index, ' ');                    totalSpace ++;                }                index++;            }            //selection index            if (totalSpace > space) {                selectionIndex += (totalSpace - space);            }            char[] tempChar = new char[buffer.length()];            buffer.getChars(0, buffer.length(), tempChar, 0);            String str = buffer.toString();            if (selectionIndex > str.length()) {                selectionIndex = str.length();            } else if (selectionIndex < 0) {                selectionIndex = 0;            }            editText.setText(str);            Editable text = editText.getText();            //set selection            Selection.setSelection(text, selectionIndex < maxLength ? selectionIndex : maxLength);            isChanged = false;        }    }}

一般银行卡号最长21位，再加上中间的5个空格，所以我们设置EditText的最大可输入长度为26

使用方法如下：

1.设置EditText的最大可输入长度为26

<EditText    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:hint="请输入您的卡号"    android:inputType="number"    android:maxLength="26"    android:singleLine="true" />  

2.添加EditText输入监听

BankCardTextWatcher.bind(mEdtBankCardNo);