I'm trying to fill a list of list List<List<String>> in Java, but when I print the elements, nothing appears!
my code:
List<String> temp = new ArrayList<>();
for (int z = 0; z < c.POSList.get("V").size(); z++) {
temp.add(c.stemmer(c.POSList.get("V").get(z)).get(0));
temp.addAll(c.ReturnListOFSynoums(c.stemmer(c.POSList.get("V").get(z)).get(0), ""));
System.out.println(temp); // there are elements !
verbsMatrix.add(temp);
temp.clear();
}
for (int s = 0; s < verbsMatrix.size(); s++) {
for (int r = 0; r < verbsMatrix.get(s).size(); r++) {
System.out.print(verbsMatrix.get(s).get(r) + " ");
}
}
You're clearing temp every time, this is the same instance you just added to verbsMatrix which you don't re-initialize.
Try declaring temp inside the for, and don't clear it.
Related
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...
I have to get the first element of each vector and add into another vector and continue till mainVector ends
mainVector -- > [[1,Allen,2000,10],[2,Joe,3000,20],[3,King,4000,40]] [Vector(Vectors)]
output should be -- > [[1,2,3],[Allen,Joe,King],[2000,3000,4000],[10,20,40]] [Vector(Vectors)]
int i=0;
Vector outputVector = new Vector();
for(int p = 0; p < mainVector.size(); p++)
{
Vector second = new Vector();
for(int h = 0; h < mainVector.size(); h++)
{
eachVector = mainVector.get(h);
String eachElement = eachVector.get(i);
second.add(eachElement);
}
outputVector.add(second);
i++;
}
Try this.
int i = 0;
Vector outputVector = new Vector();
for (int p = 0; p < ((Vector)mainVector.get(0)).size(); p++) {
Vector second = new Vector();
for (int h = 0; h < mainVector.size(); h++) {
Vector eachVector = (Vector)mainVector.get(h);
Object eachElement = eachVector.get(i);
second.add(eachElement);
}
outputVector.add(second);
i++;
}
You don't need 3 index variables, as you have a 2 dimensional data structure:
Vector outputVector = new Vector();
for (int i = 0; i < mainVector.size(); i++) {
outputVector.add(new Vector());
for (int j = 0; j < mainVector.get(0).size(); j++) {
((Vector) outputVector.get(i)).add(mainVector.get(i).get(j));
}
}
I have to point out that this seems very old school Java. Unless you have a legacy project, consider using something Vector<Vector<Object>> outputVector. Also you probably want to use List as Vector is now considered obsolete
I am trying to display the contents of an array after iterating through rows and columns of a JTable. I tried Arrays.toString(myTwoDimensionalArrayVariable) but it won't display the string values.
My goal is to check duplicates for every column per row of a destination JTable when user tries to add row values from a source JTable that's why I want to display the contents of the array.
The values on columns are combination of double, String, and int.
int myRowCount = aJTableParameter.getRowCount();
int myColumnCount = aJTableParameter.getColumnCount();
Object[][] myRowValues = new Object[myRowCount][myColumnCount];
for (int j = 0; j < myRowCount; j++) {
for(int i = 0; i< myColumnCount; i++){
myRowValues[j][i] = aDestinationTable.getValueAt(j, i);
}
}
System.out.println(Arrays.toString(myRowValues));
if (Arrays.asList(myRowValues).contains(column1Value)
&& Arrays.asList(myRowValues).contains(column2Value)
&& Arrays.asList(myRowValues).contains(column3Value)
&& Arrays.asList(myRowValues).contains(column4Value)) {
JOptionPane.showMessageDialog(null, "Duplicate, try again.");
}else{
//do something else
}
I only get this output:
run:
Successfully recorded login timestamp
[]
[[Ljava.lang.Object;#35fa3ff2]
[[Ljava.lang.Object;#407c448d, [Ljava.lang.Object;#1e78a60e]
Is there any other alternative than using 2 Dimensional Arrays?
I'd appreciate any help.
Thanks.
IFF your JTable cells contain only Strings, you can define your array as String[][] instead of Object[][] and fill it with your JTable contents using aDestinationTable.getValueAt(j, i).toString().
EDIT: since that's not the case (as per your comment), it's probably better to use a List, like this:
List<List<Object>> objectList = new ArrayList<>();
for (int j = 0; j < 2; j++) {
objectList.add(j, new ArrayList<>());
for (int i = 0; i < 2; i++) {
if (i==0) objectList.get(j).add("string" + j + i);
if (i==1) objectList.get(j).add((double) 37.8346 * j * i);
}
}
System.out.println("OBJECT LIST: "+objectList);
Output:
OBJECT LIST: [[string00, 0.0], [string10, 37.8346]]
Your code should look like this, then:
List<List<Object>> myRowValues = new ArrayList<>();
for (int j = 0; j < myRowCount; j++) {
myRowValues.add(j, new ArrayList<>());
for (int i = 0; i < myColumnCount; i++) {
myRowValues.get(j).add(aDestinationTable.getValueAt(j, i));
}
}
System.out.println(myRowValues);
I have an ArrayList of LinkedLists (an array of linked lists). The LinkedLists contains integers (Integer).
private List<LinkedList> buckets;
buckets = new ArrayList<LinkedList>();
for (int i = 0; i < 10; i++) {
LinkedList<Integer> temp = new LinkedList<Integer>();
buckets.add(temp);
}
I later want to remove the items from the linked list (in the order they were added) and add them to an array list. When I try this:
ArrayList<Integer> sorted = new ArrayList<Integer>(unsorted.size());
for (int i = 0; i < buckets.size(); i++) {
for (int j = 0; j < buckets.get(i).size(); j++) {
sorted.add(buckets.get(j).removeLast());
// sorted.add((Integer)buckets.get(j).removeLast());
}
}
I get an error saying:
add(java.lang.Integer) in ArrayList cannot be applied to (java.lang.Object)
But when I cast it to an Integer (the commented out line), the array is full of null values. Anyone see what I am doing wrong?
Here is where I am adding items to bucket:
for (int i = 0; i < unsorted.size(); i++) {
int digit = (unsorted.get(i) / position) % 10;
buckets.get(digit).add(unsorted.get(i));
}
Note that sorted is an ArrayList<Integer>. When I trace it in debug mode, I can see that the LinkedLists have Integer objects with the correct values.
Screenshot of buckets contents:
Working Example:
class Ideone {
private static List<LinkedList<Integer>> buckets;
public static void main (String[] args) throws Exception {
ArrayList<Integer> arr = new ArrayList<Integer>();
arr.add(6);
arr.add(8);
arr.add(1);
arr.add(3);
arr.add(9);
System.out.println(arr);
arr = sort(arr);
System.out.println(arr);
}
public static ArrayList<Integer> sort(ArrayList<Integer> unsorted) {
buckets = new ArrayList<LinkedList<Integer>>();
for (int i = 0; i < 10; i++) {
LinkedList<Integer> temp = new LinkedList<Integer>();
buckets.add(temp);
}
ArrayList<Integer> sorted = new ArrayList<Integer>(unsorted.size());
for (int i = 0; i < unsorted.size(); i++) {
int digit = unsorted.get(i) % 10;
buckets.get(digit).add(unsorted.get(i));
}
for (int i = 0; i < buckets.size(); i++) {
for (int j = 0; j < buckets.get(i).size(); j++) {
sorted.add(buckets.get(j).poll());
// sorted.add((Integer)buckets.get(j).removeLast());
}
}
return sorted;
}
}
You are using the raw form of LinkedList here:
private List<LinkedList> buckets;
Because of this, removeLast will return Object, not Integer. Try
private List<LinkedList<Integer>> buckets;
and
buckets = new ArrayList<LinkedList<Integer>>();
Casting the return of removeLast to Integer was the pre-generics way of getting this to work. However, you never inserted any items into each LinkedList, so removeLast returns null. If you want something returned, first insert something into each LinkedList that gets inserted into buckets.
Casting to Integer would still work, but supplying Integer as the type argument to LinkedList is preferred, especially since you are using generics by supplying LinkedList as the type parameter to List already.
In your nested loop,
for (int i = 0; i < buckets.size(); i++) {
for (int j = 0; j < buckets.get(i).size(); j++) {
// ***** here *****
sorted.add(buckets.get(j).poll());
}
}
You look to be polling the wrong List.
Try changing
sorted.add(buckets.get(j).poll());
to:
sorted.add(buckets.get(i).poll());
Perhaps a cleaner more intuitive way to code this would be something like:
for (int i = 0; i < buckets.size(); i++) {
LinkedList<Integer> innerList = buckets.get(i);
for (int j = 0; j < innerList.size(); j++) {
sorted.add(innerList.poll());
}
}
Although this may not work if the innerList has multiple items. Why not instead remove items safely with an iterator?
for (int i = 0; i < buckets.size(); i++) {
LinkedList<Integer> innerList = buckets.get(i);
for (Iterator<Integer> iterator = innerList.iterator(); iterator.hasNext();) {
sorted.add(iterator.next());
iterator.remove(); // this guy is optional
}
}
Either that or simply use get(j)
for (int i = 0; i < buckets.size(); i++) {
LinkedList<Integer> innerList = buckets.get(i);
for (int j = 0; j < innerList.size(); j++) {
sorted.add(innerList.get(j));
}
}
Although this isn't efficient use of a LinkedList
The item that you inserted into the ArrayList "sorted" is the item you took from the link list LinkedList.
But you never actually add any item to it. You simply just created a LinkedList and added it to your bucket list.
You need to add something into the temp list.
for (int i = 0; i < 10; i++) {
LinkedList<Integer> temp = new LinkedList<Integer>();
// Add something to the temp LinkedList
buckets.add(temp);
}
I want to compare two arrays and store the difference in another array
For example the two arrays might be
String[] a1 = { "cat" , "dog" };
String[] a2 = { "cat" , "rabbit" };
The resultant array would be like this
{ "rabbit" }
I use this code, but it does not work
int n = 0;
for (int k = 0; k <= temp.length; k++)
{
for (int u = 0; u <= origenal.length; u++)
{
if (temp[k] != origenal[u] && origenal[u] != temp[k])
{
temp2[n] = temp[k];
System.out.println(temp[u]);
n++;
}
}
}
This should do the trick.
String[] result = new String[100];
Int k = 0;
Boolean test = true;
for(i=0; i < a1.length; i++){
for(j=0; j < a2.length; j++){
if(a2[i].equals(a1[i])) continue;
test = false
}
if(test == false) result[k++] = a1[i];
}
I think that this may be what you are looking for. Note that it will only add to the third 'array' if the value exist in second array but not in first. In your example only rabbit will be stored, not dog (even though dog does not exist in both). This example could possibly be shortened but I wanted to keep it like this so it is easier to see what is going on.
First import:
import java.util.ArrayList;
import java.util.List;
Then do the following to populate and analyze the arrays
String a1[] = new String[]{"cat" , "dog"}; // Initialize array1
String a2[] = new String[]{"cat" , "rabbit"}; // Initialize array2
List<String> tempList = new ArrayList<String>();
for(int i = 0; i < a2.length; i++)
{
boolean foundString = false; // To be able to track if the string was found in both arrays
for(int j = 0; j < a1.length; j++)
{
if(a1[j].equals(a2[i]))
{
foundString = true;
break; // If it exist in both arrays there is no need to look further
}
}
if(!foundString) // If the same is not found in both..
tempList.add(a2[i]); // .. add to temporary list
}
tempList will now contain 'rabbit' as according to the specification. If you necessary need it to be a third array you can convert it to that quite simply by doing the following:
String a3[] = tempList.toArray(new String[0]); // a3 will now contain rabbit
To print the content of either the List or Array do:
// Print the content of List tempList
for(int i = 0; i < tempList.size(); i++)
{
System.out.println(tempList.get(i));
}
// Print the content of Array a3
for(int i = 0; i < a3.length; i++)
{
System.out.println(a3[i]);
}