Arraylist to string and back to arraylist

Question

I want to convert the ArrayList of (TestObject) to a String and vice versa. I have attached the main activity as well so you can see the methods I want to create.

MainActivity: Where ArrayList is made and needs to be converted to a String.

public class MainActivity extends AppCompatActivity {
ArrayList<TestObject> testObjects;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    testObjects = new ArrayList<>();
    testObjects.add(new TestObject("Name1", "Attribute1"));
    testObjects.add(new TestObject("Example", "Example"));
}


private String convertObjectArrayToString(ArrayList<TestObject> arrayToBeConverted){
    return null;
}

private ArrayList<TestObject> convertStringToObjectArray(){

    return null;
}

}

Object in ArrayList:

public class TestObject {

private String name;
private String attribute;

TestObject(String name, String attribute){
    this.name = name;
    this.attribute = attribute;
}

public void setAttribute(String attribute) {
    this.attribute = attribute;
}

public void setName(String name) {
    this.name = name;
}

public String getName() {
    return name;
}

public String getAttribute() {
    return attribute;
}
}

Methods are in the main activity (converObjectArrayToString and convertStringToObjectArray). — Frankie
– Frankie, Commented Feb 5, 2018 at 7:20

Athul · Accepted Answer · 2018-02-05 09:09:59Z

2

//ArrayList to String Convert :

String listToJson = new Gson().toJson(testObjects);

//ViceVersa String to get Array List :

Type listType = new TypeToken<List>() {}.getType();

List myModelList = new Gson().fromJson(listToJson, listType);

Update:

 myModelList = gson.fromJson(br, new TypeToken<ArrayList< TestObject >>(){}.getType());

edited Feb 5, 2018 at 9:09

answered Feb 5, 2018 at 7:26

Athul

8217 silver badges16 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Frankie Over a year ago

Hi, I tried converting back but i get [{attribute=Attribute1, name=Name1}, {attribute=Example, name=Example}] as the response. How would create it back to TestObject form?

Ravi Over a year ago

ArrayList to String Convert That is JSON not String. Both are different things

Hemant Parmar · Accepted Answer · 2018-02-05 07:32:51Z

0

First fill arraylist in onCreate() method:

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    testObjects = new ArrayList<>();
    testObjects.add(new TestObject("Name1", "Attribute1"));
    testObjects.add(new TestObject("Example", "Example"));
    convertObjectArrayToString(testObjects)
}

now call method for convert arraylist to string

private String convertObjectArrayToString(ArrayList<TestObject> arrayToBeConverted){

String listString = "";
for (String s : arrayToBeConverted)
{
    listString += s + "\t";
}
System.out.println(listString);
return listString;
}

implement method for string to arraylist

private ArrayList<TestObject> convertStringToObjectArray(){
Gson gson = new Gson();
TypeToken<ArrayList<Publication>> token = new TypeToken<ArrayList<TestObject>>() {
    };
ArrayList<TestObject> pb = gson.fromJson(str, token.getType());
    return testObjects ;
}

answered Feb 5, 2018 at 7:32

Hemant Parmar

4,0047 gold badges28 silver badges53 bronze badges

2 Comments

Frankie Over a year ago

Hi, I like the code, I haven't used GSON a lot but I am having a few problems. The first problem is the for loop, it wants me to change it to an object instead of a string, do you have any suggestions for that. The other problem is the TypeTokens, should that be TestObject, because it doesn't recognise the variable.

Hemant Parmar Over a year ago

well you can map arraylist to your custom object, and TypeToken is class of Gson.

Shiva Snape · Accepted Answer · 2018-02-05 07:33:55Z

Change Your DataClass : TestObject

    public class TestObject {

    private String name;
    private String attribute;

    TestObject(String name, String attribute){
        this.name = name;
        this.attribute = attribute;
    }

    public String getName() {
            return name;
        }

        public void setName(String name) {
            this.name = name;
        }

    public String getAttribute() {
            return attribute;
        }

        public void setAttribute(String attribute) {
            this.attribute = attribute;
        }

    }

For Converting ArrayList in to String :

    ArrayList<TestObject> testObjects;
     testObjects = new ArrayList<>();
     testObjects.add(new TestObject("Name1", "Attribute1"));   
     testObjects.add(new TestObject("Example", "Example"));

            for (int i=0;i<testObjects.size();i++)
            {

               String name = testObjects.get(i).getName();
               String attribute = testObjects.get(i).getAttribute();

               System.out.println(name);
               System.out.println(attribute);

            }

    You will get the items in the array list as Strings....

Collectives™ on Stack Overflow

Arraylist to string and back to arraylist

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related