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Iterate over Two Class with constants and load their fields into a HashMap

I have two java class with constants, For Ex:
public class FirstClass {
public static final String STRING_A = "STRING_A";
public static final String STRING_B = "STRING_B";
public static final String STRING_C = "STRING_C";
...
}
public class SecondClass {
public static final String STRING_AA = "STRING_AA";
public static final String STRING_BA = "STRING_BA";
public static final String STRING_CA = "STRING_CA";
...
}
Now, I want to load these constants into a,
Map< String,String> classPropertyMap = new HashMap<>(); in Such a way that, Key for this map must be a constant from FirstClass and corresponding value must be a constant from SecondClass.
If it was just one class I could use reflection to load the fields, now since the constants are from two class, how could this be done?
Finally after loading the map, the contents of the map must be something like this:
First element : key and value is < STRING_A, STRING_AA>
Second element : key and value is < STRING_B, STRING_BA>
Third element : key and value is < STRING_C, STRING_CA>

I think if you really need it, the most robust way is to put the properties to a map explicitly.
I mean map.put(FirstClass.STRING_A, SecondClass.STRING_AA); and so on.
If you use reflection you rely on the properties and their declaration order never changes. If some new property is introduced in the library, it can break your code.

Try something like below, seems you can achieve.
FirstClass first = new FirstClass();
Field[] fields = first.getClass().getFields();
SecondClass second = new SecondClass();
Field[] fields1 = second.getClass().getFields();

Try This:
FirstClass first = new FirstClass();
String[] firstStrings = first.getStrings();
//Makes a String array, and fills it with the strings from the first class.
SecondClass second = new SecondClass();
String[] secondStrings = second.getStrings();
//Makes a String array, and fills it with the strings from the second class.
HashMap<String, String> classPropertyMap = new HashMap<String, String>();
int i = 0;
//Now put strings with the same index number from both arrays into the
//HashMap
while(i <= firstStrings.length()){
classPropertyMap.put(firstStrings.get(i), secondStrings.get(i);
i++;
}
Hope that works!

Can I create an array of sets?

Here is what I am trying to do.
I am reading in a list of words with each having a level of complexity. Each line has a word followed by a comma and the level of the word. "watch, 2" for example. I wish to put all of the words of a given level into a set to ensure their uniqueness in that level. There are 5 levels of complexity, so ideally I'd like an array with 5 elements, each of which is a set.
I can then add words to each of the sets as I read them in. Later on, I wish to pull out a random word of a specified level.
I'm happy with everything except how to create an array of sets. I've read several other posts here that seem to agree that this can't be done exactly as I would hope, but I can't find a good work around. (No, I'm not willing to have 5 sets in a switch statement. Goes against the grain.)
Thanks.

You can use a map . Use level as key and value as the set which contains the words. This will help you to pull out the value for a given level, When a random word is requested from a level, get the value(set in this case) using the key which is the level and pick a random value from that. This will also scale if you increase the number of levels
public static void main(String[] args) {
Map<Integer, Set<String>> levelSet = new HashMap();
//Your code goes here to get the level and word
//
String word="";
int level=0;
addStringToLevel(levelSet,word,level);
}
private static void addStringToLevel(Map<Integer, Set<String>> levelSet,
String word, int level) {
if(levelSet.get(level) == null)
{
// this means this is the first string added for this level
// so create a container to hold the object
levelSet.put(level, new HashSet());
}
Set<String> wordContainer = levelSet.get(level);
wordContainer.add(word);
}
private static String getStringFromLevel(Map<Integer, Set<String>> levelSet,
int level) {
if(levelSet.get(level) == null)
{
return null;
}
Set<String> wordContainer = levelSet.get(level);
return "";// return a random string from wordContainer`
}

If you are willing to use Guava, try SetMultimap. It will take care of everything for you.
SetMultimap<Integer, String> map = HashMultimap.create();
map.put(5, "value");
The collection will take care of creating the inner Set instances for you unlike the array or List solutions which require either pre-creating the Sets or checking that they exist.

Consider using a List instead of an array.
Doing so might make your life easier.
List<Set<String>> wordSetLevels = new ArrayList();
// ...
for ( i = 0; i < 5; i++ ) {
wordSetLevels.add(new HashSet<String>());
}
wordSetLevels = Collections.unmodifiableList(wordSetLevels);
// ...
wordSetLevels.get(2).add("watch");

import java.util.HashSet;
import java.util.List;
import java.util.Set;
public class Main {
private Set<String>[] process(List<String> words) {
#SuppressWarnings("unchecked")
Set<String>[] arrayOfSets = new Set[5];
for(int i=0; i<arrayOfSets.length; i++) {
arrayOfSets[i] = new HashSet<String>();
}
for(String word: words) {
int index = getIndex(word);
String val = getValue(word);
arrayOfSets[index].add(val);
}
return arrayOfSets;
}
private int getIndex(String str) {
//TODO Implement
return 0;
}
private String getValue(String str) {
//TODO Implement
return "";
}
}

Android: Find a value inside an Array with a "a like" value

I'm having problem with this part
My Code:
String[] sample = {'name=NAME', 'add=ADD', 'age=AGE', 'gender=GENDER'};
for(int a = 0; a < sample.length; a++) {
if(Arrays.asList(sample).contains("name")) {
Log.d(tag, "successful");
} else {
Log.d(tag, "failed");
}
}
When I'm using this code, it doesn't return true, but when I use .contains("name=NAME")
it returns true.
Is there any possibility to compare a string value using not too specific string?
BTW, those string values came from a file.txt.

If you use Arrays.asList(sample) you will have a list containing the String "name=NAME" hence it doesn't contain the String "name"
You should loop over the array (not needed to create the list)
boolean found = false;
for (String s: sample)
if (s.contains("name"))
found=true;

To get a value based on key:
1) You can use HashMap object
import java.util.*;
import java.lang.*;
import java.io.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
public static void main(String args[]) {
// create hash map
HashMap newmap = new HashMap();
// populate hash map
newmap.put("name", "abcde");
newmap.put("age", "XX");
newmap.put("Gender", "Male");
// get value of key Gender
String val=(String)newmap.get("Gender");
// check the value
System.out.println("Value for key 3 is: " + val);
}
}
2) You can also use Map object
Map<String, String> map = new HashMap<String, String>();
map.put("name", "abcde");
map.put("age", "XX");
String val=(String)map.get("name");
3) You can also use two dimentional array of string
String data = "name=Name,age=Age";
String[] rows = data.split(",");
String[][] matrix = new String[rows.length][];
int r = 0;
for (String row : rows) {
matrix[r++] = row.split("\\=");
}
System.out.println(matrix[1][1]);

.contains method will check whether the object is present in the ArrayList or not.
Here in your case objects are : "name=NAME","add=ADD","age=AGE", "gender=GENDER" which are of String type. So it is obvious that it returns false.
For you, better practice is to create a class named Person which has attributes like name,add,age and gender. Then store the object of it in ArrayList and you can check whether object is in ArrayList of not using .contains() function. Like below :
class Person{
String name;
String add;
int age;
String gen;
// All getters and setters methods will be here.
}
public static void main(String[] args){
Person p = new Person();
//Here you can set the properties of person using p.setXXX() methods
//Now suppose you have ArrayList of Person object named "per" then you can check
// whether Person exist in it or not using contains like below
per.contains(p) //returns true if per contains object p
//or you can check name by below code
for(Person temp:per){
if(temp.getName().equals(name)){ //returns true if name matchs with Persons name
//do something
}
}

Removing common elements between two different Arraylist

I have read several posts for this but not getting the exact thing I am looking for. I know how to develop a complex logic for this, this is for Android and we can't expect too much processing on the device due to the limited resources available.
I have an ArrayList of an bean class objects consisting five fields as
Java Bean -- MyShares
fileName
filePath
fileSize
isShared
Creator
I have another ArrayList of String which contains only filepaths. Now what I want is to remove all the common elements between the two arraylist means the file paths in seconds arraylist and file path in first arraylist objects are similar then I have to remove from both of the arraylist but I don't want a new arraylist which contains the uncommon elements. But I want to get my both arraylist only without their common elements.

You could use a Map from String to your object type (I used Obj in order to make a SSCCE).
Assume we are given a list objects and a list strings.
Steps:
Put all objects in a map with their str variable as key
Get all those str variables using map.keySet()
Get all strings that are in objects but not in strings by keys.removeAll(strings)
Get all strings that are in strings but not in objects by strings.removeAll(keys)
Get the objects that correspond to the remaining keys
Note that you need to be careful in steps 3 and 4, because you need to back up one of the collections.
import java.util.*;
public class Test {
public static void main(String[] args) throws Exception {
new Test();
}
public Test() {
List<Obj> objects = new ArrayList<>();
objects.add(new Obj("a"));
objects.add(new Obj("b"));
objects.add(new Obj("c"));
List<String> strings = new ArrayList<>();
strings.add("a");
strings.add("d");
strings.add("e");
remove(objects, strings);
System.out.println(objects);
System.out.println(strings);
}
public void remove(List<Obj> objects, List<String> strings) {
Map<String, Obj> map = new HashMap<>();
for (Obj object : objects) {
map.put(object.str, object);
}
Set<String> keys = map.keySet();
List<String> oldStrings = new ArrayList<>(strings);
strings.removeAll(keys);
keys.removeAll(oldStrings);
objects.clear();
for (String key: keys) {
objects.add(map.get(key));
}
}
public class Obj {
public String str;
public Obj(String str) {
this.str = str;
}
#Override
public String toString() {
return str;
}
}
}
Prints:
[b, c]
[d, e]

Rough Java code:
HashSet<String> commonKeys = new HashSet();
for (Share share : shares) {
commonKeys.add(share.filePath);
}
commonKeys.retainAll(filePaths);
for (Iterator<Share> it = shares.iterator(); it.hasNext(); ) {
Share share = it.next();
if (commonKeys.contains(share.filePath)) {
it.remove();
}
}
filePaths.removeAll(commonKeys);
This won't be O(N) because remove on an ArrayList is expensive. To get O(N) behavior you either need to create new ArrayList instances, or add the elements you don't want removed to temporary lists, and then clear() and add them back into the original lists.

I will go with some clues for you
Suppose you have two lists one for bean objects namely myBeans and another for filePaths namely filePaths
List<MyBean> beansToRemove = new ArrayList<MyBean>();
List<FilePath> filePathsToRemove = new ArrayList<FilePath>();
for(Bean myBean : myBeans) {
for(FilePath filePath : filePaths) {
if(myBean.getfilePath.equals(filePath.getFilePath())) {
beansToRemove.add(myBean);
filePathsToRemove.add(filePath);
}
}
}
//Now remove filePaths and beans if any
for(Bean myBean : beansToRemove) {
myBeans.remove(myBean);
}
for(FilePath filePath : filePathsToRemove) {
filePaths.remove(filePath);
}
it is just a flow to make you clear for what to do; you can further customize it according to your needs.

You can use an outer loop to scan over the Bean objects, and an inner loop to scan over the file paths.
pseudo code:
for (Bean i in beans) {
for (String p in paths) {
if (i.path.equals(p)) {
beansToRemove.add(i);
pathsToRemove.add(p);
}
}
}
beans.removeAll(beansToRemove);
paths.removeAll(pathsToRemove);
I'm not sure if my extra arraylists to track the removed arraylists go against your question or not since the original arrays remain.
If you presort both arrays on the path and keep track of the position in each area (not exhaustive search) you can improve it from n2 to nlgn

Print ArrayList

I have an ArrayList that contains Address objects.
How do I print the values of this ArrayList, meaning I am printing out the contents of the Array, in this case numbers.
I can only get it to print out the actual memory address of the array with this code:
for(int i = 0; i < houseAddress.size(); i++) {
System.out.print(houseAddress.get(i));
}

list.toString() is good enough.
The interface List does not define a contract for toString(), but the AbstractCollection base class provides a useful implementation that ArrayList inherits.

Add toString() method to your address class then do
System.out.println(Arrays.toString(houseAddress));

From what I understand you are trying to print an ArrayList of arrays and one way to display that would be
System.out.println(Arrays.deepToString(list.toArray()));

since you haven't provide a custom implementation for toString() method it calls the default on which is going to print the address in memory for that object
solution
in your Address class override the toString() method like this
public class Address {
int addressNo ;
....
....
...
protected String toString(){
return Integer.toString(addressNo);
}
now when you call
houseAddress.get(i) in the `System.out.print()` method like this
System.out.print( houseAddress.get(i) ) the toString() of the Address object will be called

You can simply give it as:
System.out.println("Address:" +houseAddress);
Your output will look like [address1, address2, address3]
This is because the class ArrayList or its superclass would have a toString() function overridden.
Hope this helps.

assium that you have a numbers list like that
List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6);
if you print the list
//method 1
// Conventional way of printing arraylist
for (int number : numbers) {
System.out.print(number);
}
//method 2
// Lambda Expression to print arraylist
numbers.forEach((Integer value) -> System.out.print(value));
//method 3
// Lambda Expression to print arraylist
numbers.forEach(value -> System.out.print(value));
//method 4
// Lambda Expression (method reference) to print arraylist
numbers.forEach(System.out::print);

Are you saying that ArrayList is storing addresses of arrays because that is what is returning from the toString call, or because that's actually what you're storing?
If you have an ArrayList of arrays (e.g.
int[] arr = {1, 2, 3};
houseAddress.add(arr);
Then to print the array values you need to call Arrays.deepToString:
for (int i = 0; i < houseAddress.size(); i++) {
System.out.println(Arrays.deepToString(houseAddress.get(i)));
}

public void printList(ArrayList<Address> list){
for(Address elem : list){
System.out.println(elem+" ");
}
}

I am not sure if I understood the notion of addresses (I am assuming houseAddress here), but if you are looking for way a to print the ArrayList, here you go:
System.out.println(houseAddress.toString().replaceAll("\\[\\]", ""));

Since Java 8, you can use forEach() method from Iterable interface.
It's a default method. As an argument, it takes an object of class, which implements functional interface Consumer. You can implement Consumer locally in three ways:
With annonymous class:
houseAddress.forEach(new Consumer<String>() {
#Override
public void accept(String s) {
System.out.println(s);
}
});
lambda expression:
houseAddress.forEach(s -> System.out.println(s));
or by using method reference:
houseAddress.forEach(System.out::print);
This way of printing works for all implementations of Iterable interface.
All of them, gives you the way of defining how the elements will be printed, whereas toString() enforces printing list in one format.

Simplest way to print an ArrayList is by using toString
List<String> a=new ArrayList<>();
a.add("111");
a.add("112");
a.add("113");
System.out.println(a.toString());
Output
[111, 112, 113]

Put houseAddress.get(i) inside the brackets and call .toString() function: i.e Please see below
for(int i = 0; i < houseAddress.size(); i++) {
System.out.print((houseAddress.get(i)).toString());
}

This helped to me:
System.out.println(Arrays.toString(codeLangArray.toArray()));

public static void main(String[] args) {
List<Moyen> list = new ArrayList<Moyen>();
Moyen m1 = new Moyen();
m1.setCodification("c1");
m1.setCapacityManager("Avinash");
Moyen m2 = new Moyen();
m2.setCodification("c1");
m2.setCapacityManager("Avinash");
Moyen m3 = new Moyen();
m3.setCodification("c1");
m3.setCapacityManager("Avinash");
list.add(m1);
list.add(m2);
list.add(m3);
System.out.println(Arrays.toString(list.toArray()));
}

You can use an Iterator. It is the most simple and least controvercial thing to do over here. Say houseAddress has values of data type String
Iterator<String> iterator = houseAddress.iterator();
while (iterator.hasNext()) {
out.println(iterator.next());
}
Note : You can even use an enhanced for loop for this as mentioned by me in another answer

if you make the #Override public String toString() as comments,
you will have the same results as you did.
But if you implement your toString() method, it will work.
public class PrintingComplexArrayList {
public static void main(String[] args) {
List houseAddress = new ArrayList();
insertAddress(houseAddress);
printMe1(houseAddress);
printMe2(houseAddress);
}
private static void insertAddress(List address)
{
address.add(new Address(1));
address.add(new Address(2));
address.add(new Address(3));
address.add(new Address(4));
}
private static void printMe1(List address)
{
for (int i=0; i<address.size(); i++)
System.out.println(address.get(i));
}
private static void printMe2(List address)
{
System.out.println(address);
}
}
class Address{
private int addr;
public Address(int i)
{
addr = i;
}
#Override public String toString()
{
Integer iAddr = new Integer (addr);
return iAddr.toString();
}
}

You can even use an enhanced for loop or an iterator like:
for (String name : houseAddress) {
System.out.println(name);
}
You can change it to whatever data type houseAddress is and it avoids unnecessary conversions

Make sure you have a getter in House address class and then use:
for(int i = 0; i < houseAddress.size(); i++) {
System.out.print(houseAddress.get(i)**.getAddress()**);
}

you can use print format if you just want to print the element on the console.
for(int i = 0; i < houseAddress.size(); i++) {
System.out.printf("%s", houseAddress.get(i));
}

Assuming that houseAddress.get(i) is an ArrayList you can add toString() after the ArrayList :
for(int i = 0; i < houseAddress.size(); i++) {
System.out.print(houseAddress.get(i).toString());
}
A general example:
ArrayList<Double> a = new ArrayList();
a.add(2.);
a.add(32.);
System.out.println(a.toString());
// output
// [2.0, 32.0]

This is a simple code of add the value in ArrayList and print the ArrayList Value
public class Samim {
public static void main(String args[]) {
// Declare list
List<String> list = new ArrayList<>();
// Add value in list
list.add("First Value ArrayPosition=0");
list.add("Second Value ArrayPosition=1");
list.add("Third Value ArrayPosition=2");
list.add("Fourth Value ArrayPosition=3");
list.add("Fifth Value ArrayPosition=4");
list.add("Sixth Value ArrayPosition=5");
list.add("Seventh Value ArrayPosition=6");
String[] objects1 = list.toArray(new String[0]);
// Print Position Value
System.err.println(objects1[2]);
// Print All Value
for (String val : objects1) {
System.out.println(val);
}
}
}

JSON
An alternative Solution could be converting your list in the JSON format and print the Json-String. The advantage is a well formatted and readable Object-String without a need of implementing the toString(). Additionaly it works for any other Object or Collection on the fly.
Example using Google's Gson:
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
...
public static void printJsonString(Object o) {
GsonBuilder gsonBuilder = new GsonBuilder();
/*
* Some options for GsonBuilder like setting dateformat or pretty printing
*/
Gson gson = gsonBuilder.create();
String json= gson.toJson(o);
System.out.println(json);
}

Add toString() method to your class
houseAddress.forEach(System.out::println);

Consider using an "Enhanced for loop" I had to do this solution for a scenario in which the arrayList was coming from a class object
changing the String datatype to the appropriate datatype or class object as desired.
ArrayList<String> teamRoster = new ArrayList<String>();
// Adding player names
teamRoster.add("Mike");
teamRoster.add("Scottie");
teamRoster.add("Toni");
System.out.println("Current roster: ");
for (String playerName : teamRoster) {
System.out.println(playerName);
// if using an object datatype, you may need to use a solution such as playerName.getPlayer()
}