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generate combination of List string in java

I have a List called listTeams which comprises of Strings. I need to generate all unique combinations of these strings and store them in another ArrayList called lines. I've tried the following but the results are not desirable:
for(int i=0; i<listTeams.size();i++){
for(int j=1;j<listTeams.size();j++){
if (listTeams.get(j).equals(listTeams.get(i)))
continue;
for(int k=2;k<listTeams.size();k++){
if (listTeams.get(k).equals(listTeams.get(i)) || listTeams.get(k).equals(listTeams.get(j)))
continue;
String str = listTeams.get(i)+listTeams.get(j)+listTeams.get(k);
lines.put(str,new ArrayList<String>());
}
}
}
Here's the original list : {"A","B","C","D"}
What I am getting is
a_b_c
a_b_d
a_c_d
a_d_c
b_c_d
b_d_c
c_b_d
d_b_c
What I desire is:
a_b_c
a_b_d
a_c_d
b_c_d

for(int i=0; i<listTeams.size();i++){
for(int j=i+1;j<listTeams.size();j++){
for(int k=j+1;k<listTeams.size();k++){
String str = listTeams.get(i)+listTeams.get(j)+listTeams.get(k);
lines.put(str,new ArrayList<String>());
}
}
}

You need to modify your for loops like this:
for (int j = i;
and
for (int k = j;
So that only unique combinations appear

As #Berger said, the following code is working as you expect.
for (int i = 0; i < listTeams.size(); i++) {
for (int j = i+1; j < listTeams.size(); j++) {
if (listTeams.get(j).equals(listTeams.get(i)))
continue;
for (int k = j+1; k < listTeams.size(); k++) {
if (listTeams.get(k).equals(listTeams.get(i)) || listTeams.get(k).equals(listTeams.get(j)))
continue;
String str = listTeams.get(i) + listTeams.get(j) + listTeams.get(k);
lines.add(str);
}
}
}

CompareTo String Array - Works Explicitly, But Not Implicitly with Variables in Loop

I'm trying to compare elements in an array. When I use a variable within a loop, I get an out of bounds error. Yet when I use explicit values in place of the variables, with the same value, it works fine.
What am I missing?
The problem line is:
int result = (myList[j]).compareToIgnoreCase(myList[j + 1]);
But if I use this, it works (values should be identical):
int result = (myList[0]).compareToIgnoreCase(myList[1]);
Have searched high and dry for this. Other posters had different issues. Would appreciate any input! Here's the example with dummy content:
public class methodSortTest
{
public static void main(String[] args)
{
// Create and load data into array
String[] myList = new String[2];
myList[0] = "Charlie";
myList[1] = "Bravo";
// Compare, positive/negative
for (int j = 0; j < myList.length; j++)
{
int result = (myList[j]).compareToIgnoreCase(myList[j + 1]);
System.out.println("Result is: " + result);
}
}
}

Try this:
change this:
for (int j = 0; j < myList.length; j++)
to this:
for (int j = 0; j < myList.length-1; j++)
problem is inside this statement:
int result = (myList[j]).compareToIgnoreCase(myList[j + 1]);
because you are accessing the j+1
Simple Helping material:
https://www.geeksforgeeks.org/understanding-array-indexoutofbounds-exception-in-java/

When j equals 1, myList[j + 1] evaluates to myList[2] which throws an ArrayIndexOutOfBoundsException. There is no item at index 2 because you have only inserted items at index 0 and 1.
Reference: https://docs.oracle.com/javase/7/docs/api/java/lang/ArrayIndexOutOfBoundsException.html
Change your for loop from
for (int j = 0; j < myList.length; j++)
To
for (int j = 0; j < myList.length-1; j++) // note the "-1"

Two dimension array, how to programically add new array element? Java

I don't know, if I forgot how, or I just can't figure it out how.
For example :
Object[][] data = {
{"id", "projectname","valueid", "value"},
};
And this is how they should be added, but in loop:
Object[][] data = {
{"id", "projectname","valueid", "value"},
{"id2", "projectname2","valueid2", "value2"},
{"id3", "projectname3","valueid3", "value3"},
};
And so on..
I need a tip only, like a skeleton how it should be. I tried to figure it out, but had no idea how.
Thanks!

You can add a new array to another array like this :
data[1] = new Object[]{"id_1", "projectname_1","valueid_1", "value_1"};
...
data[n] = new Object[]{"id_n", "projectname_n","valueid_n", "value_n"};
You can use this way in any loop for example :
int length = 5;
Object[][] data = new Object[length][];
for(int i = 0; i < length; i++){
data[i] = new Object[]{...some information};
}

for (int i = 1; i < data.length; i++) {
for (int j = 0; j < data[i].length; j++) {
int line = i+1;
data[i][j] = data[0][j]+ line;
}
}

Turning 1d array into 2d

I am working on an assignment for my java class and part of the assignment requires reading in a .csv file that is 20x20 and inserting each string into an array.
I am trying to convert my 1d array from the initial reading in of the file into a 2d array, but I seem to be doing something wrong in my output of the data.
I made an add method, and when running the program and calling the method I only get one column of strings and listed in reverse order, but if I do a System.out.println() I don't the output I desire. I am still fairly new to this so I'm sure I just don't see the simple error, but to me, it looks correct.
the reading in of the file
try {
Scanner fileScanner = new Scanner(toOpen);
while (fileScanner.hasNext()) {
fromFile = fileScanner.nextLine();
String temp[] = fromFile.split(" ");
theList.add(temp[0]);
System.out.println(fromFile);
String[][] arr = new String[20][20];
int count = 0;
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
arr[i][j] = temp[i];
System.out.print(arr);
}
}
System.out.println();
}
fileScanner.close();
my add method
public void add(String tableValue) { // Adds a new node
Node newNode = new Node(tableValue);
if (isEmpty()) {
setRoot(newNode);
} else {
newNode.setNext(getRoot());
setRoot(newNode);
}
}
and my method that prints the result
public String makeString() { // A Class that makes a string
String theString = new String();
if (isEmpty()) {
theString = "List is empty";
} else {
Node printer = getRoot();
while (printer != null) {
theString += printer.getTableValue() + " ";
printer = printer.getNext();
}
}
return theString;
}

I guess your problem is here:
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
arr[i][j] = temp[i];
This assigns the same value (temp[i]) to all slots in arr[i]. Again guessing, I think you need something like:
int tmpIndex = 0;
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
arr[i][j] = temp[tmpIndex];
tmpIndex++;
In other words: you have 400 different values in temp. But your code is only assigning the first 20 values 20 times again and again.
Beyond that: System.out.print(arr); isn't doing what you expect it to do - to learn how to print arrays correctly, see this.

As we don't know the number of lines in a file, we can start by storing each line into an ArrayList (of String[]) and then convert it into a 2D array, e.g.:
List<String[]> lines = new ArrayList<>();
while (fileScanner.hasNext()) {
String line = fileScanner.nextLine();
String temp[] = line.split(" ");
lines.add(temp);
}
Now, convert it into an array:
String[][] array = new String[lines.size()][];
for(int i=0 ; i<lines.size() ; i++){
array[i] = lines.get(i);
}

I hevent seen where you have really used your add and makeString methods, and what is the role of the theList variable.
Also, could you please send your file Content.
any way:
If this is your calling to the add method: theList.add(temp[0]); that means that you are inside an Extended class structure that you have not shown it. but Any way you have not used it to fill the 2d Array in the for loop
the Code here is also error: you insert the same element temp[i] in every line !!!!
for (int i = 0; i < arr.length; i++) {
for (int j = 0; j < arr[i].length; j++) {
arr[i][j] = temp[i];
System.out.print(arr);
}
}
You can use a dynamic structure like ArrayList to fill the Elements...

Android: Methods for finding matching elements in arrays?

Hi I am stuck in a particular case
I have two arrays, ArrayA[] with 50 items and another ArrayB[] with 10 items.
I want to convert the values of the ArrayB[] (10 items) to be 1 if they match a value in ArrayA[] and 0 if they don't.
I have been trying various techniques for past 5 hours- would be great to get some guidance in what I can do to get this!
Thanks for any help!

If I understand you well, this is what you are looking for:
public static void method(int[] arrayA, int[] arrayB)
{
boolean match = false;
label: for(int i = 0; i < arrayA.length; i++)
for(int j = 0; j < arrayB.length; j++)
if(arrayA[i] == arrayB[j])
{
match = true;
break label;
}
int k = (match?1:0);
for(int i = 0; i < arrayB.length; i++)
arrayB[i] = k;
}
If not, please elaborate!

List l = Arrays.asList(arrayA);
for (int i = 0; i < arrayB.length; i++)
arrayB[i] = l.contains(arrayB[i]) ? 1 : 0;