I have a list of files in a array
String[] myStringArray = {"C:\file1.txt","C:\file2.txt","C:\file3.txt"};
For which I'm running a for loop to execute a command to get a value
for (String extpath: myStringArray ) {
command to get the metadata
}
Output:
modified
modified
unmodified
I'm able to get the above working. Now I need to compare each element of the output and see of they are same are different.
Should that again be created as a array and then be compared? any pointers please on the easiest approach
If you wish to store the output of each iteration of the loop in an array, you'll need a regular for loop, since you'll need the index of the array (unless you add a local counter variable).
String[] output = new String[myStringArray.length];
for (int i = 0; i < myStringArray.length; i++) {
String extpath = myStringArray[i];
output[i] = command to get the metadata
}
You could have a Map<String, Boolean> which you update as you go along. The key in this case, would be the name of the file while the value would be if the file has been modified or not, so basically:
Map<String, Boolean> map = new HashMap<String, Boolean>();
...
for (String extpath: myStringArray ) {
boolean result = ...
if(map.get(extPath) == result) {
//What to do if they are the same
}
else {
//What to do if they are different
}
map.get(i) = result; //Update the map
}
The code above should allow you to do what you are after with just 1 pass.
Related
I am currently working on a project where I need to check an arraylist for a certain string and if that condition is met, replace it with the new string.
I will only show the relevant code but basically what happened before is a long string is read in, split into groups of three, then those strings populate an array. I need to find and replace those values in the array, and then print them out. Here is the method that populates the arraylist:
private static ArrayList<String> splitText(String text)
{
ArrayList<String> DNAsplit = new ArrayList<String>();
for (int i = 0; i < text.length(); i += 3)
{
DNAsplit.add(text.substring(i, Math.min(i + 3, text.length())));
}
return DNAsplit;
}
How would I search this arraylist for multiple strings (Here's an example aminoAcids = aminoAcids.replaceAll ("TAT", "Y");) and then print the new values out.
Any help is greatly appreciated.
In Java 8
list.replaceAll(s-> s.replace("TAT", "Y"));
There is no such "replace all" method on a list. You need to apply the replacement element-wise; the only difference vs doing this on a single string is that you need to get the value out of the list, and set the new value back into the list:
ListIterator<String> it = DNAsplit.listIterator();
while (it.hasNext()) {
// Get from the list.
String current = it.next();
// Apply the transformation.
String newValue = current.replace("TAT", "Y");
// Set back into the list.
it.set(newValue);
}
And if you want to print the new values out:
System.out.println(DNAsplit);
Why dont you create a hashmap that has a key-value and use it during the load time to populate this list instead of revising it later ?
Map<String,String> dnaMap = new HashMap<String,String>() ;
dnaMap.push("X","XXX");
.
.
.
dnaMap.push("Z","ZZZ");
And use it like below :
//Use the hash map to lookup the temp key
temp= text.substring(i, Math.min(i + 3, text.length()));
DNAsplit.add(dnaMap.get(temp));
This function loops through a dictionary (allWords) and uses the
getKey function to generate a key. wordListMap is a HashMap> so I need to loop through and put the key and and a List. If there is not a list I put one if there is I just need to append the next dictionary word. This is where I need help. I just can't figure out the syntax to simply append the next word to the list that is already there. Any Help would be appreciated.
public static void constructWordListMap() {
wordListMap = new HashMap<>();
for (String w : allWords) {
int key = getKey(w);
if (isValidWord(w) && !wordListMap.containsKey(key)) {
List list = new ArrayList();
list.add(w);
wordListMap.put(key, list);
} else if (isValidWord(w) && wordListMap.containsKey(key)) {
wordListMap.put(key, wordListMap.get(key).add(w));
}
}
}
map.get(key).add(value)
Simple as that.
So I've gathered that you want to, given HashMap<Integer, List<String>>, you'd like to:
create a List object
add String objects to said List
add that List object as a value to be paired with a previously generated key (type Integer)
To do so, you'd want to first generate the key
Integer myKey = getKey(w);
Then, you'd enter a loop and add to a List object
List<String> myList = new List<String>;
for(int i = 0; i < intendedListLength; i++) {
String myEntry = //wherever you get your string from
myList.add(myEntry);
}
Lastly, you'd add the List to the HashMap
myHash.put(myKey, myList);
Leave any questions in the comments.
else if (isValidWord(w) && wordListMap.containsKey(key)) {
wordListMap.put(key, wordListMap.get(key).add(w));
}
If you want to add a new value to your list, you need to retrieve that list first. In the code above, you are putting the return value of add into the table (which is a boolean), and that is not what you want.
Instead, you will want to do as Paul said:
else if (isValidWord(w) && wordListMap.containsKey(key)) {
wordListMap.get(key).add(w);
}
The reason this works is because you already added an ArrayList to the table earlier. Here, you are getting that ArrayList, and adding a new value to it.
I am new to Java. I want to Parse the data which is in this Format
Apple;Mango;Orange:1234;Orange:1244;...;
There could be more than one "Orange" at any point of time. Numbers (1,2...) increase and accordingly as the "Orange".
Okay. After splitting it, Lets assume I have stored the first two data(Apple, Orange) in a variable(in setter) to return the same in the getter function. And now I want to add the value(1234,1244....etc) in the 'orange' thing into a variable to return it later. Before that i have to check how many oranges have come. For that, i know i have to use for loop. But don't know how to store the "Value" into a variable.
Please Help me guys.
String input = "Apple;Mango;Orange:1234;Orange:1244;...;"
String values[] = input.split(";");
String value1 = values[0];
String value2 = values[1];
Hashmap< String, ArrayList<String> > map = new HashMap<String, ArrayList<String>>();
for(int i = 2; i < values.length; i = i + 2){
String key = values[i];
String id = values[i+1];
if (map.get(key) == null){
map.put(key, new ArrayList<String>());
}
map.get(key).add(id);
}
//for any key s:
// get the values of s
map.get(s); // returns a list of all values added
// get the count of s
map.get(s).size(); // return the total number of values.
Let me try to rephrase the question by how I interpreted it and -- more importantly -- how it focuses on the input and output (expectations), not the actual implementation:
I need to parse the string
"Apple;Mango;Orange:1234;Orange:1244;...;"
in a way so I can retrieve the values associated (numbers after ':') with the fruits:
I should receive an empty list for both the Apple and Mango in the example, because they have no value;
I should receive a list of 1234, 1244 for Orange.
Of course your intuition of HashMap is right on the spot, but someone may always present a better solution if you don't get too involved with the specifics.
There are a few white spots left:
Should the fruits without values have a default value given?
Should the fruits without values be in the map at all?
How input errors should be handled?
How duplicate values should be handled?
Given this context, we can start writing code:
import java.util.*;
public class FruitMarker {
public static void main(String[] args) {
String input = "Apple;Mango;Orange:1234;Orange:1244";
// replace with parameter processing from 'args'
// avoid direct implementations in variable definitions
// also observe the naming referring to the function of the variable
Map<String, Collection<Integer>> fruitIds = new HashMap<String, Collection<Integer>>();
// iterate through items by splitting
for (String item : input.split(";")) {
String[] fruitAndId = item.split(":"); // this will return the same item in an array, if separator is not found
String fruitName = fruitAndId[0];
boolean hasValue = fruitAndId.length > 1;
Collection<Integer> values = fruitIds.get(fruitName);
// if we are accessing the key for the first time, we have to set its value
if (values == null) {
values = new ArrayList<Integer>(); // here I can use concrete implementation
fruitIds.put(fruitName, values); // be sure to put it back in the map
}
if (hasValue) {
int fruitValue = Integer.parseInt(fruitAndId[1]);
values.add(fruitValue);
}
}
// display the entries in table iteratively
for (Map.Entry<String, Collection<Integer>> entry : fruitIds.entrySet()) {
System.out.println(entry.getKey() + " => " + entry.getValue());
}
}
}
If you execute this code, you will get the following output:
Mango => []
Apple => []
Orange => [1234, 1244]
Say I have a hashmap with String type as key and ArrayList type as value, example {"value1"=["one","three","five"], "value2"=["two","four","six"]} where "value1" and "value2" are keys. I want to write the above hashmap data in following format. (so that I can read the csv file in excel)
value1,value2
one,two
three,four
five,six
My idea was to write the first key and its values as follows
value1
one
three
five
Then I was thinking of using the seek method in RandomAccessFile class to back to line 1 and again write the second key and its values. However I am not able to accomplish this task since seek function takes in the length of strings in the entire file and writes the new string after it. While I wanted the pointer to jump to the first line and append the string. Is there a better way to do this?. A quick example would be much appreciated.
Thanks
Why can't you just use 4 Strings, one for each row? Something like this:
StringBuilder keyRow = new StringBuilder();
StringBuilder value1 = new StringBuilder();
StringBuilder value2 = new StringBuilder();
StringBuilder value3 = new StringBuilder();
Iterator keys = hashmap.keySet().iterator();
boolean notFirst = true;
while(keys.hasNext()) {
String key = (String)keys.next();
ArrayList list = (ArrayList)hashmap.get(key);
if(!notFirst) {
keyRow.append(",");
value1.append(",");
value2.append(",");
value3.append(",");
}
keyRow.append(key);
value1.append((String)list.get(0));
value2.append((String)list.get(1));
value3.append((String)list.get(2));
notFirst = false;
}
Then at the end, just take the 4 Strings
String csv = keyRow.toString()+"\n"+value1.toString()+"\n"+value2.toString()+"\n"+value3.toString();
Note that this example isn't really proper CSV. Strings with commas aren't wrapped in quotes.
Or you iterate through the HashMap a thousand times if you have thousands of these rows. To save a bit of time from looking up a key, you can put them all in an ArrayList:
StringBuilder csv = new StringBuilder();
int row = 0;
ArrayList<ArrayList> list = new ArrayList<ArrayList>();
// Write the keys row:
Iterator keys = hashmap.keySet().iterator();
boolean notFirst = true;
while(keys.hasNext()) {
String key = (String)keys.next();
ArrayList tmp = (ArrayList)hashmap.get(key);
if(!notFirst) {
csv.append(",");
}
csv.append(key);
// store list
list.add(tmp);
notFirst = false;
}
csv.append("\n");
// Write the rest of the rows
while(row<numberOfTotalRow) {
notFirst = true;
for(int x=0;x<list.size();x++) {
if(!notFirst) {
csv.append(",");
}
csv.append((String)list.get(x).get(row));
notFirst = false;
}
row++;
}
You can make a method that prints out the map as you wish:
public void toString(HashMap<String, ArrayList<String>> map) {
for(int i = 0; i < map.size(); i++) {
ArrayList<String> list = new ArrayList<String>(map.keySet());
String key = list.get(i);
System.out.println(key);
for(int j = 0; j < map.get(key).size(); j++)
System.out.println(map.get(key).get(j));
}
}
The way you have imagined is impossible. A file is a continuous stream of bytes. So after you write the first value, you have this in your file : "value1\none\nthree\nfive". If you then seek to position 6 (after "value") and insert new characters, you'll be overwiting the first value's second row. The following bytes won't be magically pushed away.
The only way to do this is to traverse the data you have in a way that allows you to output the bytes in the same order that they will be in the file. So: go to each value and write the first element, to each value again and write their second element and so on.
You don't need a RandomAccessFile file, better use this:
HashMap<String, ArrayList<String>> map = new HashMap<>();
map.put("a", new ArrayList<>(Arrays.asList(new String[]{"A1", "A2", "A3"})));
map.put("b", new ArrayList<>(Arrays.asList(new String[]{"B1", "B2", "B3"})));
map.put("c", new ArrayList<>(Arrays.asList(new String[]{"C1", "C2", "C3"})));
{
/**
* Set your file printstream. For testing System.out
*/
PrintStream ps = System.out;
boolean first = true;
/**
* Size of the array list. Let's asume that the arraylist are of the
* same lenght;
*/
int s = 0;
/**
* Create a ArrayList variable because, this map class makes no guarantees
* as to the order of the map; in particular, it does not guarantee that
* the order will remain constant over time.
*/
ArrayList<Entry<String, ArrayList<String>>> l =
new ArrayList<>(map.entrySet());
for (Entry<String, ArrayList<String>> e : l) {
if (first) {
first = false;
s = e.getValue().size();
} else {
ps.print(",");
}
ps.print(e.getKey());
}
ps.println();
for (int i = 0; i < s; i++) {
first = true;
for (Entry<String, ArrayList<String>> e : l) {
if (first) {
first = false;
} else {
ps.print(",");
}
ps.print(
e.getValue().get(i));
}
ps.println();
}
}
Output:
b,c,a
B1,C1,A1
B2,C2,A2
B3,C3,A3
I have a problem concerning a HashMap in Java. To explain the problem in a detailed way, i will first post some code you can refer to.
public void BLASTroute(String args[]) throws IOException, InterruptedException{
...
correctMapping CM = new correctMapping();
CM.correctMapping(RB.BLASTresults, exists);
CalculateNewConsensusSequence CNCS =
new CalculateNewConsensusSequence();
char[] consensus = CNCS.calculateNewConsensusSequence(
CM.newSeq, CM.remindGaps, EMBLreaderReference.sequence, exists);
HashMap<Integer, ArrayList<String>> gapsFused =
new HashMap<Integer, ArrayList<String>>();
for (Integer i : CM.remindGaps.keySet()) {
ArrayList<String> newList = CM.remindGaps.get(i);
gapsFused.put(i, newList);
}
GenerateGeneLists GGL = new GenerateGeneLists(
EMBLreaderReference, CM.newSeq, gapsFused, exists,
GQList, allMappedPositions);
System.out.println(CM.remindGaps.hashCode());
gapsFused=GGL.generateGeneListSNP(gapsFused);
System.out.println(CM.remindGaps.hashCode());
System.out.println(gapsFused.hashCode());
GGL.generateGeneListFrameShift(gapsFused);
}
The following occurs:
in my class correctMapping, i fill a global variable called remindGaps. I use it later in some functions, and nothing happens/everything works as expected.
Then, i make a copy of the HashMap called gapsFused (i don't know if this has something to do with my problem).
Now comes the interesting part: In the class GenerateGeneLists, i don't do a thing with the remindGaps HashMap.
However, after the function generateGeneListSNP is performed, remindGaps changed! I'll post the code for you as well, so that you can help me better:
public GenerateGeneLists(EMBL_reader EMBLreaderReference,
HashMap<String,ArrayList<String>> newSeq,
HashMap<Integer,ArrayList<String>> gapsFused, File exists,
ArrayList<GeneQualifier> GQlist,
HashMap<Integer,Integer> allMappedPositions)
throws InterruptedException{
this.EMBLreaderReference=EMBLreaderReference;
this.newSeq=newSeq;
//this.gapsFused=gapsFused;
this.exists=exists;
this.GQlist=GQlist;
this.allMappedPositions=allMappedPositions;
for (GeneQualifier GQ : this.GQlist){
startlist.add(GQ.start);
stoplist.add(GQ.stop);
startMap.put(GQ.start,GQ);
}
}
public HashMap<Integer,ArrayList<String>> generateGeneListSNP(
HashMap<Integer,ArrayList<String>> gapsFused)
throws IOException{
File GQSNP = new File (exists+"/GQsnp.txt");
BufferedWriter SNP = new BufferedWriter(new FileWriter(GQSNP));
SNP.write("#Gene_start\tGene_stop\tlocus_tag\tproduct" +
"\tputative_SNP_positions(putative_changes)\n");
HashMap<GeneQualifier,ArrayList<Integer>> GQreminder =
new HashMap<GeneQualifier,ArrayList<Integer>>();
for (String s : newSeq.keySet()){
ArrayList<String> blub = newSeq.get(s);
char[] qrySeq = blub.get(0).toCharArray();
char[] refSeq = blub.get(1).toCharArray();
int start = Integer.valueOf(blub.get(2));
int stop = Integer.valueOf(blub.get(3));
for (int i=0;i<refSeq.length;i++){
if (qrySeq[i]!=refSeq[i]&&qrySeq[i]!='-'&&qrySeq[i]!='.'){
if (mismatchList.containsKey(start+i)){
ArrayList<Character> blah = mismatchList.get(start+i);
blah.add(qrySeq[i]);
mismatchList.put(start+i, blah);
}
else {
ArrayList<Character> blah = new ArrayList<Character>();
blah.add(qrySeq[i]);
mismatchList.put(start+i,blah);
}
}
else if (qrySeq[i]!=refSeq[i]&&(qrySeq[i]=='-'||qrySeq[i]=='.')){
if (!gapsFused.containsKey(start+i)){
ArrayList<String> qwer = new ArrayList<String>();
qwer.add(String.valueOf(qrySeq[i]));
gapsFused.put(start+i,qwer);
}
else {
ArrayList<String> qwer = gapsFused.get(start+i);
qwer.add(String.valueOf(qrySeq[i]));
gapsFused.put(start+i,qwer);
}
if (!deletionPositionsAndCount.containsKey((start+i))){
int count = 1;
deletionPositionsAndCount.put(start+i, count);
}
else {
int count = deletionPositionsAndCount.get(start+i);
count = count+1;
deletionPositionsAndCount.put(start+i, count);
}
}
}
}
for (Integer a : mismatchList.keySet()){
for (int i=0;i<startlist.size();i++){
int start = startlist.get(i);
int stop = stoplist.get(i);
if (a>=start && a<=stop){
GeneQualifier GQ = startMap.get(start);
if (!GQreminder.containsKey(GQ)){
ArrayList save = new ArrayList<Integer>();
save.add(a);
GQreminder.put(GQ,save);
}
else {
ArrayList save = GQreminder.get(GQ);
save.add(a);
GQreminder.put(GQ,save);
}
break;
}
}
}
for (GeneQualifier GQ : GQreminder.keySet()) {
ArrayList<Integer> save = GQreminder.get(GQ);
int start = GQ.start;
int stop = GQ.stop;
String locus_tag =
GQ.geneFeatures.get("locus_tag").get(0).replace("\n", "");
String product =
GQ.geneFeatures.get("product").get(0).replace("\n", "");
SNP.write(start + "\t" + stop + "\t" + locus_tag +
"\t" + product + "\t");
boolean end = false;
for (int i = 0; i < save.size(); i++) {
if (i==save.size()-1) end=true;
int posi = save.get(i);
SNP.write(posi + "(");
ArrayList<Character> mismatches = mismatchList.get(posi);
for (int j = 0; j < mismatches.size(); j++) {
char snipp = mismatches.get(j);
if (j == mismatches.size() - 1) {
SNP.write(snipp + ")");
} else {
SNP.write(snipp + ",");
}
}
if (end == false){
SNP.write(",");
}
}
SNP.write("\n");
}
SNP.close();
return gapsFused;
}
As you can see, remindGaps is not used in this class, but still it undergoes changes. Do you have an idea why this is the case?
What I tested is, whether remindGaps changes if i manually change gapsFused (the made copy of the first HashMap). This is not the case, so i don't think that the copying process went wrong (for example only points to the other HashMap or references it).
I would really appreciate your ideas and help in order to solve this problem.
You have to remember that in Java all objects are passed as reference. So, when you did:
ArrayList<String> newList = CM.remindGaps.get(i);
you basically pointed newList to the same list as contained in the remindGaps map. Now, even though you work with the gapsFused, any changes to its values effect the same underlying list in the memory - to which both remindGaps and gapsFused are pointing.
Change your copy code to the following and see if it makes a difference:
ArrayList<String> newList = new ArrayList<String>(CM.remindGaps.get(i));
By doing this, you are creating a new list that newList will be pointing to and thus the changes will be encapsulated.
Your code is very long and hard to read (mainly because it doesn't respect Java naming conventions), but my guess is that your problem comes from the fact that your copy of the map simply copies the ArrayList references from one map to another:
HashMap<Integer, ArrayList<String>> gapsFused = new HashMap<Integer, ArrayList<String>>();
for (Integer i : CM.remindGaps.keySet()) {
ArrayList<String> newList = CM.remindGaps.get(i);
gapsFused.put(i, newList);
}
In the above code, you don't create any new list. You just store the same lists in another map. If you need a new list, the code should be:
Map<Integer, List<String>> gapsFused = new HashMap<Integer, List<String>>();
for (Integer i : CM.remindGaps.keySet()) {
List<String> newList = new ArrayList<STring>(CM.remindGaps.get(i));
gapsFused.put(i, newList);
}
Without analyzing all your code:
HashMap<Integer, ArrayList<String>> gapsFused = new HashMap<Integer, ArrayList<String>>();
for (Integer i : CM.remindGaps.keySet()) {
ArrayList<String> newList = CM.remindGaps.get(i);
gapsFused.put(i, newList);
}
After this code gapFused will contain entries that are copies of the entries of remindGaps, therefore those entries will reference the same objects (key and values). So if you add or remove entries in one Map it will have no effect on the other, but if you change a value accessing it through one Map you will see the change also accessing it through the other map (for example remingGaps.get(1).add("hello")).
The name "newList" used in your code is confusing because it is not a new list, just a reference on an existing one...
Since the value of the Map is an ArrayList and you are doing just a shallow copy (meaning the new Map has a reference to the same Lists as are in the first Map) and changes to the lists in the second map would be reflected in the first map. To avoid this you would need to make deep copies of the lists when you create the new Map.