Mad Scientist :
I have a for loop which iterates through a maplist and now I want to check every entry of the maplist if it contains a certain String more than once and then delete all Strings except the first one which occurs but I have no clue how to do it.
for (Map<String, String> entry : mapList) {
String line = "";
for (String key : entry.keySet()) {
if (StringUtils.containsAny(key, "5799"){
line += entry.get(key) + "|";
}
list1.add(line);
}
}
I am thankful for every idea.
Andreas :
To see if key
contains a string s
at least twice, and to remove the second occurrence, use indexOf
twice, with the second call starting the search after the first occurrence:
static String removeSecond(String key, String s) {
int idxFirst = key.indexOf(s);
if (idxFirst != -1) {
int idxSecond = key.indexOf(s, idxFirst + s.length());
if (idxSecond != -1) {
return key.substring(0, idxSecond) +
key.substring(idxSecond + s.length());
}
}
return key; // Nothing to remove
}
Test
System.out.println(removeSecond("mississippi", "ss")); // prints: missiippi
System.out.println(removeSecond("mississippi", "i")); // prints: missssippi
System.out.println(removeSecond("mississippi", "pp")); // prints: mississippi
UPDATE
If you want to remove all duplicates, i.e. leave only the first occurrence, keep searching. For best performance of building the new string, use StringBuilder
.
static String removeDuplicates(String key, String s) {
int idx = key.indexOf(s);
if (idx == -1)
return key; // Nothing to remove
StringBuilder buf = new StringBuilder();
int prev = 0;
for (int start = idx + s.length(); (idx = key.indexOf(s, start)) != -1; prev = start = idx + s.length())
buf.append(key.substring(prev, idx));
return (prev == 0 ? key : buf.append(key.substring(prev)).toString());
}
Test
System.out.println(removeDuplicates("mississippi", "ss")); // prints: missiippi
System.out.println(removeDuplicates("mississippi", "i")); // prints: misssspp
System.out.println(removeDuplicates("mississippi", "s")); // prints: misiippi
System.out.println(removeDuplicates("mississippi", "ab")); // prints: mississippi
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