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How do I get object and not address without using String/ toString?

I need to create my own String class called MyString without using default String class/vector API. I have to work on some required methods, and their return types are predetermined. I can add other methods as long as String is not used.
Expected use would be:
(at main) System.out.println(str.toLowerCase()) - returns lower case of str
When I want to work with toLowerCase() method with return type MyString, I can't return the object content but only return the address.
Normally, this problem would require modification of toString(), but since this method requires return type of String by default, I can't use modification of toString() for the assignment.
The assignment is supposed to be not so hard and should not require complex extensions. My constructor may be the problem, but I can't specify which part is.
Code
public class MyString {
private char value[];
MyString(char[] arr){
this.value = Arrays.copyOf(arr, arr.length);
}
...
MyString toLowerCase() { // can't change return type
for (int i =0; i<value.length; i++) {
if ((int)value[i] > 64 && (int)value[i] < 91) {
value[i] = (char) (value[i]+32);
}
}
return this; // this returns address, and I can't override toString
}

Problem with System.out.println(str.toLowerCase()) is it ends up calling PrintStream.println(Object o), but that method internally at some point calls o.toString() which uses code inherited from Object#toString() (since you couldn't override toString as it expect as result String which is forbidden in your project) which result in form TypeInfo#hexHashCode.
This means you can't use System.out.println(MyString).
BUT PrintStream (which instance is held by System.out) allows us to provide data to print in different forms. In this case you can use println(char[]). All you need to do is adding to MyString method like toCharArray() which would return (preferably a copy of) array of characters held by MyString class.
This way you can use it like System.out.println(myStringInstance.toCharArray()) so code from your main method would need to look like
System.out.println(str.toLowerCase().toCharArray());
// ^^^^^^^^^^^--this should return char[]

Firstly, the String class is an immutable type, i.e. the methods of String do not change the internal state (i.e. the char array), instead they return a new instance of type String.
To mirror that behavior you could implement something like this:
public MyString toLowerCase() {
char temp = new char[value.length];
// [...] Your code performing the actual logic on temp
return new MyString(temp);
}
The immutability (and its implications) of the String class is very important to understand in practice. For example, the following code procudes the intended result:
String word = "Word";
System.out.println("I can produce upper case (" + word.toUpperCase() + ") " +
"and lower case (" + word.toLowerCase() + ") " +
"without any side-effects on the original (" + word + ").");
However, it's not possible (without "hacky" solutions) to implement a method like this:
void shortenString(String inputAndOutput);
Second, the assignment expects that the class/method must be used as follows:
System.out.println(str.toLowerCase());
The attribute out is effectively a PrintStream, which offers (besides other methods) the following two:
println(Object x) - Prints an Object and then terminate the line.
println(String x) - Prints a String and then terminate the line.
If the method is called with an Object parameter, the internal implementation calls toString() on the given object, thus the only way to satisfy the requirement is to override this method. Unfortunately, this is not allowed by the assignment.
However, if it is not explicitly stated that the solution has to use java.lang.System, you could simply implement your own System class which accepts MyString, e.g.:
public class System {
public static class MyPrintStream /* optional: extends PrintStream */ {
public void println(MyString x) {
java.lang.System.out.println(x.getCharArray());
}
}
public static final out = new MyPrintStream();
}
This would allow you to use it exactly as described in the assignment:
import my.package.System;
public class Main {
public static void main(String[] args) {
// [...] Instantiate str
System.out.println(str.toLowerCase());
}
}

How to write the contents of my array in a text file?

I have an array which has objects of people in a football team. It holds information such as their first name, second name and address. When i use the code shown below the text file contains values like this: member#29086037
The code is shown below:
try
{
PrintWriter pr = new PrintWriter ("memberDetails.txt");
for (int i = 0; i < collection.length; i++)
{
pr.println(collection[i]);
}
pr.close();
} catch (FileNotFoundException ex)
{
System.out.println(ex.getMessage());
System.out.println("in" + System.getProperty("user.dir"));
System.exit(1);
}
What am I doing wrong?

When you see that malarky with the numbers and class name like that, it means you haven't overriden your toString() method, so it defaults to Object.toString().
So, override the public String toString() method on your member class.

When you do pr.println(collection[i]); as you didn't override it, you print Object::toString which represents the object in this way by default:
The toString method for class Object returns a string consisting of the name of the class of which the object is an instance, the at-sign character `#', and the unsigned hexadecimal representation of the hash code of the object. In other words, this method returns a string equal to the value of:
getClass().getName() + '#' + Integer.toHexString(hashCode())
To print each field, use properties of the object, for example:
collection[i].getName();
collection[i].getAddress();
Other option, is to override toString() method of member.

You have to provide the path to the file correctly. I would suggest creating a file object and then pass it to Printwriter. This way you can also make sure if File exist before assigning it to printwriter.

As others have pointed out, assuming you have a class that models the players, you should provide a toString() implementation in the class. For example:
public class Player {
private String firstName;
private String lastName;
private String address;
...
#Override
public String toString() {
return String.format("Name: %s, %s. Address: %s", lastName, firstName, address);
}
}
After that's been done, it becomes trivial to write the player information into a file. Using an utility library such as Google's Guava, the solution simplifies into a one-liner:
Files.write(Joiner.on(StandardSystemProperty.LINE_SEPARATOR.value())
.join(collection),
new File("memberDetails.txt"),
Charsets.UTF_8);

toString method is returning random characters

for some reason when I run my app, instead of getting the name of the lecture, I get a bunch of random characters that show up. I'm not sure why though. Thanks in advance!
public Lecture(String lecturename) {
this.lecturename = lecturename;
listofwork = new ArrayList<Work>();
}
public String toString(Lecture lecture) {
return lecture.lecturename;
}
/////////// IN ANOTHER ACTIVITY /////////////////////
Lecture test = new Lecture("TEST");
Toast.makeText(getApplicationContext(), test.toString(), Toast.LENGTH_LONG).show();
And instead of getting a toast saying "TEST", I get whatsmymark.Lecture#41abcf8. I have a feeling its returning the actual lecture object rather than the string. However, I can't find out why cause the code is so simple.

You are writing a toString that takes a Lecture as an argument, and calling toString() that takes no arguments. If you change your method definition to have no args, you will override the Object.toString() correctly.
public String toString() {
return this.lecturename;
}
If you do not want to change your method definition for some reason, your other option is to call your version explicitly, but I am sure you will agree this looks a little redundant.
Lecture test = new Lecture("TEST");
Toast.makeText(getApplicationContext(), test.toString(test), Toast.LENGTH_LONG).show();

When you do test.toString(), you're printing the *test object itself *, not a string representing the object. Because you didn't override Object#toString() (you overloaded it instead), your object inherits this implementation:
public String toString() {
return getClass().getName() + "#" + Integer.toHexString(hashCode());
}
And that's probably not what you wanted.
What you'll need to do is put the toString() method you have inside the Lecture class, and remove its formal parameter. Then it should work.
A good idea is to put the #Override annotation on methods you intended to override. This way if you accidentally mess up the compiler should emit an error/warning letting you know.

you may want to change your code like this
public Lecture(String lecturename) {
this.lecturename = lecturename;
listofwork = new ArrayList<Work>();
public String toString() {
return this.lecturename;
}
}

Implementing an ArrayQueue in java need toString method

I have an ArrayQueue I am implementing for a class in the java language.
I am storing transaction objects in the ArrayQueue and I am getting stuck at the display() method (aka my own toString()). But it is only returning the reference.
Here is my method:
//display the elements in the current queue
public String display() {
String result = "";
if(isEmpty()) {
throw new EmptyQueueException("Queue is empty.");
} else {
for (int i = 0; i < count; i++) {
result += "[" + Q[(front + i) % capacity] + "] ";
}
}
return result;
}
Does this mean I need a toString() method for my object and call it like: System.out.println(arrayqueue.display().toString())?

If you override toString() for your ArrayQueue class, you can use:
System.out.println(arrayqueue);
But if you choose to call it display(), then yes you need this:
System.out.println(arrayqueue.display())
How else is the runtime environment supposed to know you wanted the string representation instead of the object reference?

Does this mean I need a toString() method for my object and call it like: System.out.println(arrayqueue.display().toString())?
No, since display() returns a String, arrayqueue.display() should be sufficient. Are you perhaps trying to print the toString() value of arrayqueue? Without overriding toString(), it will return the class name and hash code by default.

When you call the code
result += "[" + Q[(front + i) % capacity] + "] ";
You are calling the toString() method on the object contained at that location in the Q array. Default object toString() will print its memory location. If you have different data already declared by your object to print, such as object.getClass() to print the objects class name for instance you won't have to override toString() but instead call that method within the above code. Of course if you want a custom string that better represents your object than its memory location, its good to override toString() within that object's class.

arraylist returning random numbers and not proper data

so I've got an arraylist
private static ArrayList<Job> teamNoOne = new ArrayList<Job>();
Of type Job, which has
public class Job {
//public long time;
public int teamNo;
public String regNo;
public String gridRef;
}
Then I'm getting data from a textField
Job job = new Job();
job.gridRef = tfGridRef.getText();
This all works, printed it to system etc.
When I add it to the arraylist, and print it out using the following code:
teamNoOne.add(job);
System.out.println(teamNoOne.get(0));
I just get this: Job#1c79dfc
cannot for the life of me figure out why,
Cheers

When a object is printed using sysout, its toString method is called. If toString method is not overridden in the class, then its default implementation will be used. Default implementation of an object toString method prints the class name and the unsigned hexadecimal representation of the hash code of the object separated by # symbol.
You need to override the toString method in your Job class in order to print the object in a pretty way. Most of the IDEs provide a way to auto- generate the toString method. Here is one generated through eclipse:
#Override
public String toString() {
return "Job [teamNo=" + teamNo + ", regNo=" + regNo + ", gridRef="
+ gridRef + "]";
}