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Saving a String into a file, then loading it into a String variable will give a "different" string that seems to have the exact same name [duplicate]

This question already has answers here:
How do I compare strings in Java?
(23 answers)
Closed 3 years ago.
So I am having an issue, I put my self to the test of creating a 2D sandbox game kind of for fun, but has turned out evolving into something a bit more after about a week, but, to the point, I am saving chunk data into a few files, these are just .file or, just the most basic file type I assume, and the problem persists even using .txt files.
So what's happening is after saving a file containing the object name, x, and y positions, I am creating an object in a linked list using that information, when I enter a new "chunk", but things are not exactly right, somehow, my images load up for the tiles correctly, which is handled in the constructor for that tile, being called after it is added to the list, however, what made me notice is I have a check in the tiles update method, to see if it wants to change to a different grass texture, and it doesn't happen, so I did some checking and printing, and well, I can tell that the name variable certainly contains the desired name, eg. "dirt", however it does not equal "dirt", so I thought it was catching some spaces and I even trimmed the String, and when I run a test like
if(name == "dirt")System.out.print("dirt is actually "+name);
else System.out.print("dirt is apparently not "+name);
and the result is always, "dirt is apparently not dirt", with no spaces, and even when looking in the actual file I save it to, it saves the name fine, I have them saving in an order like so;
name x y
eg.
dirt 0 560
dirt 28 560
and so on, these all load in position perfectly fine and what stumps me is that the initial image loads in correctly, which is quite explicit, a switch statement to determine what the image, material type and such should be..
I was wondering if anyone has come across something like this and what it could possibly be.
Also any code desired I will add to the desc.
(I didn't know so many people would be so quick to help. Thank you all, I know it was a simple problem, but it had me super confused, now thanks to you all I understand something about comparing variables and objects I should have really known before, and which is really important
.)

Chances are the result is "dirt" but you're not testing it correctly.
Test should be if name.equals("dirt") ... not the equality operator ==.
See: How do I compare strings in Java?

Equality in Java:
String dirt1 = "dirt";
String dirt2 = new String("dirt");
System.out.println(dirt1 == "dirt"); // TRUE
System.out.println(dirt1 == dirt2); // FALSE
System.out.println(dirt1 == dirt2.intern()); // TRUE
System.out.println(dirt1.equals(dirt2)); // TRUE

Parsing a string into different variable types

Relatively new to programming here so I apologize if this is rather basic.
I am trying to convert string lines into actual variables of different types.
My input is a file in the following format:
double d1, d2 = 3.14, d3;
int a, b = 17, c, g;
global int gInt = 1;
final int fInt = 2;
String s1, s2 = "Still with me?", s3;
These lines are all strings at this point. I wish to extract the variables from the strings and receive the actual variables so I can use and manipulate them.
So far I've tried using regex but I'm stumbling here. Would love some direction as to how this is possible.
I thought of making a general type format for example:
public class IntType{
boolean finalFlag;
boolean globalFlag;
String variableName;
IntType(String variableName, boolean finalFlag, boolean globalFlag){
this.finalflag = finalFlag;
this.globalFlag = globalFlag;
this.variableName = variableName;
}
}
Creating a new wrapper for each of the variable types.
By using and manipulating I would like to then compare between the wrappers I've created and check for duplicate declarations etc'.
But I don't know if I'm on the right path.
Note: Disregard bad format (i.e. no ";" at the end and so on)

While others said that this is not possible, it actually is. However it goes somewhat deep into Java. Just search for java dynamic classloading. For example here:
Method to dynamically load java class files
It allows you do dynamically load a java file at runtime. However your current input does not look like a java file but it can easily be converted to one by wrapping it with a small wrapper class like:
public class CodeWrapper() {
// Insert code from file here
}
You can do this with easy file or text manipulations before loading the ressource as class.
After you have loaded the class you can access its variables via reflection, for example by
Field[] fields = myClassObject.getClass().getFields();
This allows you to access the visibility modifier, the type of the variable, the name, the content and more.
Of course this approach presumes that your code actually is valid java code.
If it is not and you are trying to confirm if it is, you can try to load it. If it fails, it was non-valid.

I have no experience with Java, but as far as my knowledge serves me, it is not possible to actually create variables using a file in any language. You'll want to create some sort of list object which can hold a variable amount of items of a certain type. Then you can read the values from a file, parse them to the type you want it to be, and then save it to the list of the corresponding type.
EDIT:
If I were you, I would change my file layout if possible. It would then look something like this:
1 2 3 4 //1 int, 2 floats, 3 booleans and 4 strings
53
3.14
2.8272
true
false
false
#etc.
In pseudo code, you would then read it as follows:
string[] input = file.Readline().split(' '); // Read the first line and split on the space character
int[] integers = new int[int.Parse(input[0])] // initialise an array with specefied elements
// Make an array for floats and booleans and strings the same way
while(not file.eof) // While you have not reached the end of the file
{
integers.insert(int.Parse(file.ReadLine())) // parse your values according to the size which was given on the first line of the file
}
If you can not change the file layout, then you'll have to do some smart string splitting to extract the values from the file and then create some sort of dynamic array which resizes as you add more values to it.
MORE EDITS:
Based on your comment:
You'll want to split on the '=' character first. From the first half of the split, you'll want to search for a type and from the second half, you can split again on the ',' to find all the values.

Writing/reading array to file

I have an app that will create 3 arrays : 2 with double values and one with strings that can contain anything,alphanumeric,commas,points,anything the user might want to type or type by accident. The double arrays are easy.The string one i find to be tricky.
It can contain stuff like cake red,blue 1kg paper-clip,you get the ideea.
I will need to store those arrays somehow(i guess in a file is the easiest way),read them and get them back into the app whenever the user wants to.
Also,it would be well if they wouldn't be human readable,to only be able to read them thru my app.
What's the best way to do this ? My issue is,how can i read them back into arrays.Its easy to write to a file but then to get them back in the same array i put them in...How can i separate array elements for it not to split one element in two because it has a space or any other element.
Can i like,make 3 rows of text,each element split by a tab \t or something and when i read it each element will by split by that tab ? Will this be able to create any issues when reading ?
I guess i want to know how can i split the elements of the array so that it won't be able to ever read them wrong.
Thanks and have a nice day !

If you don't want the file to be human readable, you could usejava.io.RandomAccessFile.
You would probably want to specify a maximum string size if you did this.
To save a string:
String str = "hello";
RandomAccessFile file = new RandomAccessFile(new File("filename"));
final int MAX_STRING_BYTES = 100; // max number of bytes the string could use in the file
file.writeUTF(str);
file.skipBytes(MAX_STRING_BYTES - str.getBytes().length);
// then write another..
To read a string:
// instantiate again
final int STRING_POSITION = 100; // or whichever place you saved it
file.seek(STRING_POSITION);
String str = new String(file.read(MAX_STRING_BYTES));
You would probably want a use the beginning of the file to store the size of each array. Then just store all the values one by one in the file, no need for separators.

Preferred way of getting the selected item of a JComboBox

HI,
Which is the correct way to get the value from a JComboBox as a String and why is it the correct way. Thanks.
String x = JComboBox.getSelectedItem().toString();
or
String x = (String)JComboBox.getSelectedItem();

If you have only put (non-null) String references in the JComboBox, then either way is fine.
However, the first solution would also allow for future modifications in which you insert Integers, Doubless, LinkedLists etc. as items in the combo box.
To be robust against null values (still without casting) you may consider a third option:
String x = String.valueOf(JComboBox.getSelectedItem());

The first method is right.
The second method kills kittens if you attempt to do anything with x after the fact other than Object methods.

String x = JComboBox.getSelectedItem().toString();
will convert any value weather it is Integer, Double, Long, Short into text
on the other hand,
String x = String.valueOf(JComboBox.getSelectedItem());
will avoid null values, and convert the selected item from object to string

Don't cast unless you must. There's nothign wrong with calling toString().

Note this isn't at heart a question about JComboBox, but about any collection that can include multiple types of objects. The same could be said for "How do I get a String out of a List?" or "How do I get a String out of an Object[]?"

JComboBox mycombo=new JComboBox(); //Creates mycombo JComboBox.
add(mycombo); //Adds it to the jframe.
mycombo.addItem("Hello Nepal"); //Adds data to the JComboBox.
String s=String.valueOf(mycombo.getSelectedItem()); //Assigns "Hello Nepal" to s.
System.out.println(s); //Prints "Hello Nepal".

small java problem

Sorry if my question sounds dumb. But some time small things create big problem for you and take your whole time to solve it. But thanks to stackoverflow where i can get GURU advices. :)
So here is my problem. i search for a word in a string and put 0 where that word occur.
For example : search word is DOG and i have string "never ever let dog bite you" so the string
would be 000100 . Now when I try to convert this string into INT it produce result 100 :( which is bad. I also can not use int array i can only use string as i am concatinating it, also using somewhere else too in program.
Now i am sure you are wondering why i want to convert it into INT. So here my answer. I am using 3 words from each string to make this kind of binary string. So lets say i used three search queries like ( dog, dog, ever ) so all three strings would be
000100
000100
010000
Then I want to SUM them it should produce result like this "010200" while it produce result "10200" which is wrong. :(
Thanks in advance

Of course the int representation won't retain leading zeros. But you can easily convert back to a String after summing and pad the zeros on the left yourself - just store the maximum length of any string (assuming they can have different lengths). Or if you wanted to get even fancier you could use NumberFormat, but you might find this to be overkill for your needs.
Also, be careful - you will get some unexpected results with this code if any word appears in 10 or more strings.

Looks like you might want to investigate java.util.BitSet.

You could prefix your value with a '1', that would preserve your leading 0's. You can then take that prefix into account you do your sum in the end.
That all is assuming you work through your 10 overflow issue that was mentioned in another comment.

Could you store it as a character array instead? Your using an int, which is fine, but your really not wanting an int - you want each position in the int to represent words in a string, and you turn them on or off (1 or 0). Seems like storing them in a character array would make more sense.