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How to get String between last two underscore

I have a string "abcde-abc-db-tada_x12.12_999ZZZ_121121.333"
The result I want should be 999ZZZ
I have tried using:
private static String getValue(String myString) {
Pattern p = Pattern.compile("_(\\d+)_1");
Matcher m = p.matcher(myString);
if (m.matches()) {
System.out.println(m.group(1)); // Should print 999ZZZ
}
else {
System.out.println("not found");
}
}

If you want to continue with a regex based approach, then use the following pattern:
.*_([^_]+)_.*
This will greedily consume up to and including the second to last underscrore. Then it will consume and capture 9999ZZZ.
Code sample:
String name = "abcde-abc-db-tada_x12.12_999ZZZ_121121.333";
Pattern p = Pattern.compile(".*_([^_]+)_.*");
Matcher m = p.matcher(name);
if (m.matches()) {
System.out.println(m.group(1)); // Should print 999ZZZ
} else {
System.out.println("not found");
}
Demo

Using String.split?
String given = "abcde-abc-db-tada_x12.12_999ZZZ_121121.333";
String [] splitted = given.split("_");
String result = splitted[splitted.length-2];
System.out.println(result);

Apart from split you can use substring as well:
String s = "abcde-abc-db-tada_x12.12_999ZZZ_121121.333";
String ss = (s.substring(0,s.lastIndexOf("_"))).substring((s.substring(0,s.lastIndexOf("_"))).lastIndexOf("_")+1);
System.out.println(ss);
OR,
String s = "abcde-abc-db-tada_x12.12_999ZZZ_121121.333";
String arr[] = s.split("_");
System.out.println(arr[arr.length-2]);

The get text between the last two underscore characters, you first need to find the index of the last two underscore characters, which is very easy using lastIndexOf:
String s = "abcde-abc-db-tada_x12.12_999ZZZ_121121.333";
String r = null;
int idx1 = s.lastIndexOf('_');
if (idx1 != -1) {
int idx2 = s.lastIndexOf('_', idx1 - 1);
if (idx2 != -1)
r = s.substring(idx2 + 1, idx1);
}
System.out.println(r); // prints: 999ZZZ
This is faster than any solution using regex, including use of split.

As I misunderstood the logic from the code in question a bit with the first read and in the meantime there appeared some great answers with the use of regular expressions, this is my try with the use of some methods contained in String class (it introduces some variables just to make it more clear to read, it could be written in the shorter way of course) :
String s = "abcde-abc-db-ta__dax12.12_999ZZZ_121121.333";
int indexOfLastUnderscore = s.lastIndexOf("_");
int indexOfOneBeforeLastUnderscore = s.lastIndexOf("_", indexOfLastUnderscore - 1);
if(indexOfLastUnderscore != -1 && indexOfOneBeforeLastUnderscore != -1) {
String sub = s.substring(indexOfOneBeforeLastUnderscore + 1, indexOfLastUnderscore);
System.out.println(sub);
}

How to display the characters upto a specific index of a String using String function?

I have my string defined as
text1:text2:text3:text4:text5
I want to get output as
text1:text2:text3
using String methods.
I have tried using lastIndexOf, then substring and then again lastIndexOf.
I want to avoid these three steps with calling lastIndexOf two times.
Is there a better way to achieve this?

You can do this by running a loop to iterate over the characters of the string from index = 0 to index = lastIndexOf('3'). Here's the code:
String s = "text1:text2:text3:text4:text5";
for(int i = 0; i < = s.lastIndexOf('3'); i++)
System.out.print(s.charAt(i));
This gives you the required output.
OUTPUT:
text1:text2:text3

A regular expression could be used to identify the correct part of the string:
private static Pattern PATTERN = Pattern.compile("([^:]*:){2}[^:]*(?=:|$)");
public static String find(String input) {
Matcher m = PATTERN.matcher(input);
return m.find() ? m.group() : null;
}
Alternatively do not use substring between every call of lastIndexOf, but use the version of lastIndexOf that restricts the index range:
public static String find(String input, int colonCount) {
int lastIndex = input.length();
while (colonCount > 0) {
lastIndex = input.lastIndexOf(':', lastIndex-1);
colonCount--;
}
return lastIndex >= 0 ? input.substring(0, lastIndex) : null;
}
Note that here colonCount is the number of : that are left out of the string.

You could try:
String test = "text1:text2:text3:text4:text5";
String splitted = text.split(":")
String result = "";
for (int i = 0; i <3; i++) {
result += splitted[i] + ":"
}
result = result.substring(0, result.length() -1)

You can use the Java split()-method:
String string = "text1:text2:text3:text4:text5";
String[] text = string.split(":");
String text1 = text[0];
String text2 = text[1];
String text3 = text[2];
And then generate the output directly or with a for-loop:
// directly
System.out.println(text1 + ":" + text2 + ":" + text3);
// for-loop. Just enter, how many elements you want to display.
for(int i = 0; i < 3; i++){
System.out.println(text[i] + " ");
}
Output:
text1 text2 text3
The advantage of using this method is, that your input and output can be a bit more complex, because you have power over the order in which the words can be printed.
Example:
Consider Master Yoda.
He has a strange way of talking and often mixes up the sentence structure. When he introduces himself, he says the (incorrect!) senctence: "Master Yoda my name is".
Now, you want to create an universal translator, that - of course - fixes those mistakes while translating from one species to another.
You take in the input-string and "divide" it into its parts:
String string = "Master:Yoda:my:name:is"
String[] text = string.split(":");
String jediTitle = text[0];
String lastName = text[1];
String posessivePronoun = text[2];
String noun = text[3];
String linkingVerb = text[4];
The array "text" now contains the sentence in the order that you put it in. Now your translator can analyze the structure and correct it:
String correctSentenceStructure = posessivePronoun + " " + noun + " " + linkingVerb + " " + jediTitle + " " + lastName;
System.out.println(correctSentenceStructure);
Output:
"My name is Master Yoda"
A working translator might be another step towards piece in the galaxy.

Maby try this one-line s.substring(0, s.lastIndexOf('3')+1);
Complete example:
package testing.project;
public class Main {
public static void main(String[] args) {
String s = "text1:text2:text3:text4:text5";
System.out.println(s.substring(0, s.lastIndexOf('3')+1));
}
}
Output:
text1:text2:text3

How do I replace all the letters in a string with another character using Java?

I want to be able to replace all the letters in a string with an underscore character.
So for example, lets say that my string is made up of the alpha characters: "Apple". How would I convert that into five underscores, because apple has five characters (letters) in it?

You can use the String.replaceAll() method.
To replace all letters:
String originalString = "abcde1234";
String underscoreString = originalString.replaceAll("[a-zA-Z]","_");
If you meant all characters:
String originalString = "abcde1234";
String underscoreString = originalString .replaceAll(".", "_");

Why not ignore the "replace" idea and simply create a new string with the same number of underscores...
String input = "Apple";
String output = new String(new char[input .length()]).replace("\0", "_");
//or
String output2 = StringUtils.repeat("_", input .length());
largely from here.
As many others have said, replaceAll is probably the way to go if you don't want to include whitespace. For this you don't need the full power of regex but unless the string is absolutely huge it certainly wouldn't hurt.
//replaces all non-whitespace with "_"
String output3 = input.replaceAll("\S", "_");

String content = "apple";
String replaceContent = "";
for (int i = 0; i < content.length(); i++)
{
replaceContent = replaceContent + content.replaceAll("^\\p{L}+(?: \\p{L}+)*$", "_");
}
System.out.println(replaceContent);
Use Regular Expression
Regarding \p{L}: Refer Unicode Regular Expressions

Try this one.
String str = "Apple";
str = str.replaceAll(".", "_");
System.out.println(str);

Try this,
String sample = "Apple";
StringBuilder stringBuilder = new StringBuilder();
for(char value : sample.toCharArray())
{
stringBuilder.append("_");
}
System.out.println(stringBuilder.toString());

stringToModify.replaceAll("[a-zA-Z]","_");

You could do
int length = "Apple".length();
String underscores = new String(new char[length]).replace("\0", "_");

str.replaceAll("[a-zA-Z]","_");
String str="stackoverflow";
StringBuilder builder=new StringBuilder();
for(int i=0;i<str.length();i++){
builder.append('_');
}
System.out.println(builder.toString());

Sure, I'll toss in an alternative:
String input = "Apple";
char[] newCharacters = new char[input.length()];
Arrays.fill(newCharacters, '_');
String underscores = new String(newCharacters);

Or here's a nice, recursive approach:
public static void main(String[] args) {
System.out.println(underscores("Apple"));
}
public static String underscores(String input) {
if (input.isEmpty()) return "";
else return "_" + underscores(input.substring(1));
}

What about this
public static void main(String args[]) {
String word="apple";
for(int i=0;i<word.length();i++) {
word = word.replace(word.charAt(i),'_');
}
System.out.println(word);
}

Java get Substring value from String

I have string
String path = /mnt/sdcard/Album/album3_137213136.jpg
I want to only strings album3.
How can I get that substring.
I am using substring through index.
Is there any other way because album number is getting changed because it will fail in like album9, album10.

You can use a regular expression, but it seems like using index is the simplest in this case:
int start = path.lastIndexOf('/') + 1;
int end = path.lastIndexOf('_');
String album = path.substring(start, end);
You might want to throw in some error checking in case the formatting assumptions are violated.

Try this
public static void main(String args[]) {
String path = "/mnt/sdcard/Album/album3_137213136.jpg";
String[] subString=path.split("/");
for(String i:subString){
if(i.contains("album")){
System.out.println(i.split("_")[0]);
}
}
}

Obligatory regex solution using String.replaceAll:
String album = path.replaceAll(".*(album\\d+)_.*", "$1");
Use of it:
String path = "/mnt/sdcard/Album/album3_137213136.jpg";
String album = path.replaceAll(".*(album\\d+)_.*", "$1");
System.out.println(album); // prints "album3"
path = "/mnt/sdcard/Album/album21_137213136.jpg";
album = path.replaceAll(".*(album\\d+)_.*", "$1");
System.out.println(album); // prints "album21"

Using Paths:
final String s = Paths.get("/mnt/sdcard/Album/album3_137213136.jpg")
.getFileName().toString();
s.subString(0, s.indexOf('_'));
If you don't have Java 7, you have to resort to File:
final String s = new File("/mnt/sdcard/Album/album3_137213136.jpg").getName();
s.subString(0, s.indexOf('_'));

Use regex to match the substring
path.matches(".*album[0-9]+.*")

Try this ..
String path = /mnt/sdcard/Album/album3_137213136.jpg
path = path.subString(path.lastIndexOf("/")+1,path.indexOf("_"));
System.out.println(path);

How to count substring in String in java
At line no 8 we have to used for loop
another optional case replace for loop using just while loop like as while(true){. . .}
public class SubString {
public static void main(String[] args) {
int count = 0 ;
String string = "hidaya: swap the Ga of Gates with the hidaya: of Bill to make Bites."
+ " The hidaya: of Bill will then be swapped hidaya: with the Ga of Gates to make Gall."
+ " The new hidaya: printed out would be Gall Bites";
for (int i = 0; i < string.length(); i++)
{
int found = string.indexOf("hidaya:", i);//System.out.println(found);
if (found == -1) break;
int start = found + 5;// start of actual name
int end = string.indexOf(":", start);// System.out.println(end);
String subString = string.substring(start, end); //System.out.println(subString);
if(subString != null)
count++;
i = end + 1; //advance i to start the next iteration
}
System.out.println("In given String hidaya Occurred "+count+" time ");
}
}

check how many times string contains character 'g' in eligible string

How we can check any string that contains any character how may time....
example:
engineering is a string contains how many times 'g' in complete string

I know this is and old question, but there is an option that wasn't answered and it's pretty simple one-liner:
int count = string.length() - string.replaceAll("g","").length()

Try this
int count = StringUtils.countMatches("engineering", "e");
More about StringUtils can be learned from the question: How do I use StringUtils in Java?

I would use a Pattern and Matcher:
String string = "engineering";
Pattern pattern = Pattern.compile("([gG])"); //case insensitive, use [g] for only lower
Matcher matcher = pattern.matcher(string);
int count = 0;
while (matcher.find()) count++;

Although Regex will work fine, but it is not really required here. You can do it simply using a for-loop to maintain a count for a character.
You would need to convert your string to a char array: -
String str = "engineering";
char toCheck = 'g';
int count = 0;
for (char ch: str.toCharArray()) {
if (ch == toCheck) {
count++;
}
}
System.out.println(count);
or, you can also do it without converting to charArray: -
for (int i = 0; i < str.length(); i++) {
if (str.charAt(i) == toCheck) {
count++;
}
}

String s = "engineering";
char c = 'g';
s.replaceAll("[^"+ c +"]", "").length();

Use regex [g] to find the char and count the findings as below:
Pattern pattern = Pattern.compile("[g]");
Matcher matcher = pattern.matcher("engineering");
int countCharacter = 0;
while(matcher.find()) {
countCharacter++;
}
System.out.println(countCharacter);
If you want case insensitive count, use regex as [gG] in the Pattern.

use org.apache.commons.lang3 package for use StringUtils class.
download jar file and place it into lib folder of your web application.
int count = StringUtils.countMatches("engineering", "e");

You can try Java-8 way. Easy, simple and more readable.
long countOfA = str.chars().filter(ch -> ch == 'g').count();

this is a very very old question but this might help someone ("_")
you can Just simply use this code
public static void main(String[] args){
String mainString = "This is and that is he is and she is";
//To find The "is" from the mainString
String whatToFind = "is";
int result = countMatches(mainString, whatToFind);
System.out.println(result);
}
public static int countMatches(String mainString, String whatToFind){
String tempString = mainString.replaceAll(whatToFind, "");
//this even work for on letter
int times = (mainString.length()-tempString.length())/whatToFind.length();
//times should be 4
return times;
}

You can try following :
String str = "engineering";
int letterCount = 0;
int index = -1;
while((index = str.indexOf('g', index+1)) > 0)
letterCount++;
System.out.println("Letter Count = " + letterCount);

You can loop through it and keep a count of the letter you want.
public class Program {
public static int countAChars(String s) {
int count = 0;
for(char c : s.toCharArray()) {
if('a' == c) {
count++;
}
}
return count;
}
}
or you can use StringUtils to get a count.
int count = StringUtils.countMatches("engineering", "e");

This is an old question and it is in Java but I will answer it in Python. This might be helpful:
string = 'E75;Z;00001;'
a = string.split(';')
print(len(a)-1)