【android】EditText输入银行卡号每四位空一格

偏执的太偏执、 2022-06-12 02:41 335阅读 0赞

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

2.添加EditText输入监听

BankCardTextWatcher.bind(mEdtBankCardNo);