如果您以编程方式实例化EditText，Martins的答案将不起作用。我继续并修改了DigitsKeyListenerAPI 14中的包含类，以允许逗号和句点作为小数点分隔符。
要使用此功能，调用setKeyListener()的EditText，比如
// Don't allow for signed input (minus), but allow for decimal points
editText.setKeyListener( new MyDigitsKeyListener( false, true ) );
但是，在TextChangedListener用逗号替换逗号的过程中，仍然需要使用马丁的技巧
import android.text.InputType;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import android.text.method.NumberKeyListener;
import android.view.KeyEvent;
class MyDigitsKeyListener extends NumberKeyListener {
/**
* The characters that are used.
*
* @see KeyEvent#getMatch
* @see #getAcceptedChars
*/
private static final char[][] CHARACTERS = new char[][] {
new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9' },
new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-' },
new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.', ',' },
new char[] { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '-', '.', ',' },
};
private char[] mAccepted;
private boolean mSign;
private boolean mDecimal;
private static final int SIGN = 1;
private static final int DECIMAL = 2;
private static MyDigitsKeyListener[] sInstance = new MyDigitsKeyListener[4];
@Override
protected char[] getAcceptedChars() {
return mAccepted;
}
/**
* Allocates a DigitsKeyListener that accepts the digits 0 through 9.
*/
public MyDigitsKeyListener() {
this(false, false);
}
/**
* Allocates a DigitsKeyListener that accepts the digits 0 through 9,
* plus the minus sign (only at the beginning) and/or decimal point
* (only one per field) if specified.
*/
public MyDigitsKeyListener(boolean sign, boolean decimal) {
mSign = sign;
mDecimal = decimal;
int kind = (sign ? SIGN : 0) | (decimal ? DECIMAL : 0);
mAccepted = CHARACTERS[kind];
}
/**
* Returns a DigitsKeyListener that accepts the digits 0 through 9.
*/
public static MyDigitsKeyListener getInstance() {
return getInstance(false, false);
}
/**
* Returns a DigitsKeyListener that accepts the digits 0 through 9,
* plus the minus sign (only at the beginning) and/or decimal point
* (only one per field) if specified.
*/
public static MyDigitsKeyListener getInstance(boolean sign, boolean decimal) {
int kind = (sign ? SIGN : 0) | (decimal ? DECIMAL : 0);
if (sInstance[kind] != null)
return sInstance[kind];
sInstance[kind] = new MyDigitsKeyListener(sign, decimal);
return sInstance[kind];
}
/**
* Returns a DigitsKeyListener that accepts only the characters
* that appear in the specified String. Note that not all characters
* may be available on every keyboard.
*/
public static MyDigitsKeyListener getInstance(String accepted) {
// TODO: do we need a cache of these to avoid allocating?
MyDigitsKeyListener dim = new MyDigitsKeyListener();
dim.mAccepted = new char[accepted.length()];
accepted.getChars(0, accepted.length(), dim.mAccepted, 0);
return dim;
}
public int getInputType() {
int contentType = InputType.TYPE_CLASS_NUMBER;
if (mSign) {
contentType |= InputType.TYPE_NUMBER_FLAG_SIGNED;
}
if (mDecimal) {
contentType |= InputType.TYPE_NUMBER_FLAG_DECIMAL;
}
return contentType;
}
@Override
public CharSequence filter(CharSequence source, int start, int end,
Spanned dest, int dstart, int dend) {
CharSequence out = super.filter(source, start, end, dest, dstart, dend);
if (mSign == false && mDecimal == false) {
return out;
}
if (out != null) {
source = out;
start = 0;
end = out.length();
}
int sign = -1;
int decimal = -1;
int dlen = dest.length();
/*
* Find out if the existing text has '-' or '.' characters.
*/
for (int i = 0; i < dstart; i++) {
char c = dest.charAt(i);
if (c == '-') {
sign = i;
} else if (c == '.' || c == ',') {
decimal = i;
}
}
for (int i = dend; i < dlen; i++) {
char c = dest.charAt(i);
if (c == '-') {
return ""; // Nothing can be inserted in front of a '-'.
} else if (c == '.' || c == ',') {
decimal = i;
}
}
/*
* If it does, we must strip them out from the source.
* In addition, '-' must be the very first character,
* and nothing can be inserted before an existing '-'.
* Go in reverse order so the offsets are stable.
*/
SpannableStringBuilder stripped = null;
for (int i = end - 1; i >= start; i--) {
char c = source.charAt(i);
boolean strip = false;
if (c == '-') {
if (i != start || dstart != 0) {
strip = true;
} else if (sign >= 0) {
strip = true;
} else {
sign = i;
}
} else if (c == '.' || c == ',') {
if (decimal >= 0) {
strip = true;
} else {
decimal = i;
}
}
if (strip) {
if (end == start + 1) {
return ""; // Only one character, and it was stripped.
}
if (stripped == null) {
stripped = new SpannableStringBuilder(source, start, end);
}
stripped.delete(i - start, i + 1 - start);
}
}
if (stripped != null) {
return stripped;
} else if (out != null) {
return out;
} else {
return null;
}
}
}
