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 CompareVersions(String version1, String version2)
{
String[] string1Vals = version1.split("\\.");
String[] string2Vals = version2.split("\\.");
int length = Math.max(string1Vals.length, string2Vals.length);
for (int i = 0; i < length; i++)
{
Integer v1 = (i < string1Vals.length)?Integer.parseInt(string1Vals[i]):0;
Integer v2 = (i < string2Vals.length)?Integer.parseInt(string2Vals[i]):0;
//Making sure Version1 bigger than version2
if (v1 > v2)
{
return 1;
}
//Making sure Version1 smaller than version2
else if(v1 < v2)
{
return -1;
}
}
//Both are equal
return 0;
}
其他回答
我喜欢@Peter Lawrey的想法,我把它扩展到更远的范围:
/**
* Normalize string array,
* Appends zeros if string from the array
* has length smaller than the maxLen.
**/
private String normalize(String[] split, int maxLen){
StringBuilder sb = new StringBuilder("");
for(String s : split) {
for(int i = 0; i<maxLen-s.length(); i++) sb.append('0');
sb.append(s);
}
return sb.toString();
}
/**
* Removes trailing zeros of the form '.00.0...00'
* (and does not remove zeros from, say, '4.1.100')
**/
public String removeTrailingZeros(String s){
int i = s.length()-1;
int k = s.length()-1;
while(i >= 0 && (s.charAt(i) == '.' || s.charAt(i) == '0')){
if(s.charAt(i) == '.') k = i-1;
i--;
}
return s.substring(0,k+1);
}
/**
* Compares two versions(works for alphabets too),
* Returns 1 if v1 > v2, returns 0 if v1 == v2,
* and returns -1 if v1 < v2.
**/
public int compareVersion(String v1, String v2) {
// Uncomment below two lines if for you, say, 4.1.0 is equal to 4.1
// v1 = removeTrailingZeros(v1);
// v2 = removeTrailingZeros(v2);
String[] splitv1 = v1.split("\\.");
String[] splitv2 = v2.split("\\.");
int maxLen = 0;
for(String str : splitv1) maxLen = Math.max(maxLen, str.length());
for(String str : splitv2) maxLen = Math.max(maxLen, str.length());
int cmp = normalize(splitv1, maxLen).compareTo(normalize(splitv2, maxLen));
return cmp > 0 ? 1 : (cmp < 0 ? -1 : 0);
}
希望它能帮助到别人。它通过了interviewbit和leetcode中的所有测试用例(需要取消compareVersion函数中的两行注释)。
很容易测试!
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 class VersionComparator {
/* loop through both version strings
* then loop through the inner string to computer the val of the int
* for each integer read, do num*10+<integer read>
* and stop when stumbling upon '.'
* When '.' is encountered...
* see if '.' is encountered for both strings
* if it is then compare num1 and num2
* if num1 == num2... iterate over p1++, p2++
* else return (num1 > num2) ? 1 : -1
* If both the string end then compare(num1, num2) return 0, 1, -1
* else loop through the longer string and
* verify if it only has trailing zeros
* If it only has trailing zeros then return 0
* else it is greater than the other string
*/
public static int compareVersions(String v1, String v2) {
int num1 = 0;
int num2 = 0;
int p1 = 0;
int p2 = 0;
while (p1 < v1.length() && p2 < v2.length()) {
num1 = Integer.parseInt(v1.charAt(p1) + "");
num2 = Integer.parseInt(v2.charAt(p2) + "");
p1++;
p2++;
while (p1 < v1.length() && p2 < v2.length() && v1.charAt(p1) != '.' && v2.charAt(p2) != '.') {
if (p1 < v1.length()) num1 = num1 * 10 + Integer.parseInt(v1.charAt(p1) + "");
if (p2 < v2.length()) num2 = num2 * 10 + Integer.parseInt(v2.charAt(p2) + "");
p1++;
p2++;
}
if (p1 < v1.length() && p2 < v2.length() && v1.charAt(p1) == '.' && v2.charAt(p2) == '.') {
if ((num1 ^ num2) == 0) {
p1++;
p2++;
}
else return (num1 > num2) ? 1 : -1;
}
else if (p1 < v1.length() && p2 < v2.length() && v1.charAt(p1) == '.') return -1;
else if (p1 < v1.length() && p2 < v2.length() && v2.charAt(p2) == '.') return 1;
}
if (p1 == v1.length() && p2 == v2.length()) {
if ((num1 ^ num2) == 0) return 0;
else return (num1 > num2) ? 1 : -1;
}
else if (p1 == v1.length()) {
if ((num1 ^ num2) == 0) {
while (p2 < v2.length()) {
if (v2.charAt(p2) != '.' && v2.charAt(p2) != '0') return -1;
p2++;
}
return 0;
}
else return (num1 > num2) ? 1 : -1;
}
else {
if ((num1 ^ num2) == 0) {
while (p1 < v1.length()) {
if (v1.charAt(p1) != '.' && v1.charAt(p1) != '0') return 1;
p1++;
}
return 0;
}
else return (num1 > num2) ? 1 : -1;
}
}
public static void main(String[] args) {
System.out.println(compareVersions("11.23", "11.21.1.0.0.1.0") ^ 1);
System.out.println(compareVersions("11.21.1.0.0.1.0", "11.23") ^ -1);
System.out.println(compareVersions("11.23", "11.23.0.0.0.1.0") ^ -1);
System.out.println(compareVersions("11.2", "11.23") ^ -1);
System.out.println(compareVersions("11.23", "11.21.1.0.0.1.0") ^ 1);
System.out.println(compareVersions("1.21.1.0.0.1.0", "2.23") ^ -1);
System.out.println(compareVersions("11.23", "11.21.1.0.0.1.0") ^ 1);
System.out.println(compareVersions("11.23.0.0.0.0.0", "11.23") ^ 0);
System.out.println(compareVersions("11.23", "11.21.1.0.0.1.0") ^ 1);
System.out.println(compareVersions("1.5.1.3", "1.5.1.3.0") ^ 0);
System.out.println(compareVersions("1.5.1.4", "1.5.1.3.0") ^ 1);
System.out.println(compareVersions("1.2.1.3", "1.5.1.3.0") ^ -1);
System.out.println(compareVersions("1.2.1.3", "1.22.1.3.0") ^ -1);
System.out.println(compareVersions("1.222.1.3", "1.22.1.3.0") ^ 1);
}
}
public static int compareVersions(String version1, String version2){
String[] levels1 = version1.split("\\.");
String[] levels2 = version2.split("\\.");
int length = Math.max(levels1.length, levels2.length);
for (int i = 0; i < length; i++){
Integer v1 = i < levels1.length ? Integer.parseInt(levels1[i]) : 0;
Integer v2 = i < levels2.length ? Integer.parseInt(levels2[i]) : 0;
int compare = v1.compareTo(v2);
if (compare != 0){
return compare;
}
}
return 0;
}
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;
}