是否有比较版本号的标准习语?我不能直接使用String compareTo,因为我还不知道点释放的最大数量是多少。我需要比较版本,并有以下保持正确:
1.0 < 1.1
1.0.1 < 1.1
1.9 < 1.10
是否有比较版本号的标准习语?我不能直接使用String compareTo,因为我还不知道点释放的最大数量是多少。我需要比较版本,并有以下保持正确:
1.0 < 1.1
1.0.1 < 1.1
1.9 < 1.10
当前回答
public int compare(String v1, String v2) {
v1 = v1.replaceAll("\\s", "");
v2 = v2.replaceAll("\\s", "");
String[] a1 = v1.split("\\.");
String[] a2 = v2.split("\\.");
List<String> l1 = Arrays.asList(a1);
List<String> l2 = Arrays.asList(a2);
int i=0;
while(true){
Double d1 = null;
Double d2 = null;
try{
d1 = Double.parseDouble(l1.get(i));
}catch(IndexOutOfBoundsException e){
}
try{
d2 = Double.parseDouble(l2.get(i));
}catch(IndexOutOfBoundsException e){
}
if (d1 != null && d2 != null) {
if (d1.doubleValue() > d2.doubleValue()) {
return 1;
} else if (d1.doubleValue() < d2.doubleValue()) {
return -1;
}
} else if (d2 == null && d1 != null) {
if (d1.doubleValue() > 0) {
return 1;
}
} else if (d1 == null && d2 != null) {
if (d2.doubleValue() > 0) {
return -1;
}
} else {
break;
}
i++;
}
return 0;
}
其他回答
下面是一个优化的实现:
public static final Comparator<CharSequence> VERSION_ORDER = new Comparator<CharSequence>() {
@Override
public int compare (CharSequence lhs, CharSequence rhs) {
int ll = lhs.length(), rl = rhs.length(), lv = 0, rv = 0, li = 0, ri = 0;
char c;
do {
lv = rv = 0;
while (--ll >= 0) {
c = lhs.charAt(li++);
if (c < '0' || c > '9')
break;
lv = lv*10 + c - '0';
}
while (--rl >= 0) {
c = rhs.charAt(ri++);
if (c < '0' || c > '9')
break;
rv = rv*10 + c - '0';
}
} while (lv == rv && (ll >= 0 || rl >= 0));
return lv - rv;
}
};
结果:
"0.1" - "1.0" = -1
"1.0" - "1.0" = 0
"1.0" - "1.0.0" = 0
"10" - "1.0" = 9
"3.7.6" - "3.7.11" = -5
"foobar" - "1.0" = -1
public static void main(String[] args) {
String version1 = "1.0";
String version2 = "1.0.0";
String[] version1_splits = version1.split("\\.");
String[] version2_splits = version2.split("\\.");
int length = version1_splits.length >= version2_splits.length ? version1_splits.length : version2_splits.length;
int i=0;
for(;i<length;i++){
int version1_int = getValue(version1_splits,i);
int version2_int = getValue(version2_splits,i);
if(version1_int > version2_int){
System.out.println("version1 > version2");
break;
}
else if(version1_int < version2_int){
System.out.println("version2 > version1");
break;
}
else{
if(i == length-1)
System.out.println("version1 = version2");
}
}
}
private static int getValue(String[] version1_splits, int i) {
int temp;
try{
temp = Integer.valueOf(version1_splits[i]);
}
catch(IndexOutOfBoundsException e){
temp=0;
}
return temp;
}
用点作为分隔符对字符串进行标记,然后从左边开始并排比较整数转换。
// VersionComparator.java
import java.util.Comparator;
public class VersionComparator implements Comparator {
public boolean equals(Object o1, Object o2) {
return compare(o1, o2) == 0;
}
public int compare(Object o1, Object o2) {
String version1 = (String) o1;
String version2 = (String) o2;
VersionTokenizer tokenizer1 = new VersionTokenizer(version1);
VersionTokenizer tokenizer2 = new VersionTokenizer(version2);
int number1 = 0, number2 = 0;
String suffix1 = "", suffix2 = "";
while (tokenizer1.MoveNext()) {
if (!tokenizer2.MoveNext()) {
do {
number1 = tokenizer1.getNumber();
suffix1 = tokenizer1.getSuffix();
if (number1 != 0 || suffix1.length() != 0) {
// Version one is longer than number two, and non-zero
return 1;
}
}
while (tokenizer1.MoveNext());
// Version one is longer than version two, but zero
return 0;
}
number1 = tokenizer1.getNumber();
suffix1 = tokenizer1.getSuffix();
number2 = tokenizer2.getNumber();
suffix2 = tokenizer2.getSuffix();
if (number1 < number2) {
// Number one is less than number two
return -1;
}
if (number1 > number2) {
// Number one is greater than number two
return 1;
}
boolean empty1 = suffix1.length() == 0;
boolean empty2 = suffix2.length() == 0;
if (empty1 && empty2) continue; // No suffixes
if (empty1) return 1; // First suffix is empty (1.2 > 1.2b)
if (empty2) return -1; // Second suffix is empty (1.2a < 1.2)
// Lexical comparison of suffixes
int result = suffix1.compareTo(suffix2);
if (result != 0) return result;
}
if (tokenizer2.MoveNext()) {
do {
number2 = tokenizer2.getNumber();
suffix2 = tokenizer2.getSuffix();
if (number2 != 0 || suffix2.length() != 0) {
// Version one is longer than version two, and non-zero
return -1;
}
}
while (tokenizer2.MoveNext());
// Version two is longer than version one, but zero
return 0;
}
return 0;
}
}
// VersionTokenizer.java
public class VersionTokenizer {
private final String _versionString;
private final int _length;
private int _position;
private int _number;
private String _suffix;
private boolean _hasValue;
public int getNumber() {
return _number;
}
public String getSuffix() {
return _suffix;
}
public boolean hasValue() {
return _hasValue;
}
public VersionTokenizer(String versionString) {
if (versionString == null)
throw new IllegalArgumentException("versionString is null");
_versionString = versionString;
_length = versionString.length();
}
public boolean MoveNext() {
_number = 0;
_suffix = "";
_hasValue = false;
// No more characters
if (_position >= _length)
return false;
_hasValue = true;
while (_position < _length) {
char c = _versionString.charAt(_position);
if (c < '0' || c > '9') break;
_number = _number * 10 + (c - '0');
_position++;
}
int suffixStart = _position;
while (_position < _length) {
char c = _versionString.charAt(_position);
if (c == '.') break;
_position++;
}
_suffix = _versionString.substring(suffixStart, _position);
if (_position < _length) _position++;
return true;
}
}
例子:
public class Main
{
private static VersionComparator cmp;
public static void main (String[] args)
{
cmp = new VersionComparator();
Test(new String[]{"1.1.2", "1.2", "1.2.0", "1.2.1", "1.12"});
Test(new String[]{"1.3", "1.3a", "1.3b", "1.3-SNAPSHOT"});
}
private static void Test(String[] versions) {
for (int i = 0; i < versions.length; i++) {
for (int j = i; j < versions.length; j++) {
Test(versions[i], versions[j]);
}
}
}
private static void Test(String v1, String v2) {
int result = cmp.compare(v1, v2);
String op = "==";
if (result < 0) op = "<";
if (result > 0) op = ">";
System.out.printf("%s %s %s\n", v1, op, v2);
}
}
输出:
1.1.2 == 1.1.2 ---> same length and value
1.1.2 < 1.2 ---> first number (1) less than second number (2) => -1
1.1.2 < 1.2.0 ---> first number (1) less than second number (2) => -1
1.1.2 < 1.2.1 ---> first number (1) less than second number (2) => -1
1.1.2 < 1.12 ---> first number (1) less than second number (12) => -1
1.2 == 1.2 ---> same length and value
1.2 == 1.2.0 ---> first shorter than second, but zero
1.2 < 1.2.1 ---> first shorter than second, and non-zero
1.2 < 1.12 ---> first number (2) less than second number (12) => -1
1.2.0 == 1.2.0 ---> same length and value
1.2.0 < 1.2.1 ---> first number (0) less than second number (1) => -1
1.2.0 < 1.12 ---> first number (2) less than second number (12) => -1
1.2.1 == 1.2.1 ---> same length and value
1.2.1 < 1.12 ---> first number (2) less than second number (12) => -1
1.12 == 1.12 ---> same length and value
1.3 == 1.3 ---> same length and value
1.3 > 1.3a ---> first suffix ('') is empty, but not second ('a') => 1
1.3 > 1.3b ---> first suffix ('') is empty, but not second ('b') => 1
1.3 > 1.3-SNAPSHOT ---> first suffix ('') is empty, but not second ('-SNAPSHOT') => 1
1.3a == 1.3a ---> same length and value
1.3a < 1.3b ---> first suffix ('a') compared to second suffix ('b') => -1
1.3a < 1.3-SNAPSHOT ---> first suffix ('a') compared to second suffix ('-SNAPSHOT') => -1
1.3b == 1.3b ---> same length and value
1.3b < 1.3-SNAPSHOT ---> first suffix ('b') compared to second suffix ('-SNAPSHOT') => -1
1.3-SNAPSHOT == 1.3-SNAPSHOT ---> same length and value
最好的方法是重用现有代码, 使用Maven的ComparableVersion类
优点:
Apache许可证,版本2.0, 测试, 在多个项目中使用(复制),如spring-security-core, jboss等 多个特性 它已经是java.lang。可比的了 只是复制粘贴一个类,没有第三方依赖
不要包含对maven-artifact的依赖项,因为那会拉动各种传递依赖项