Method in ArrayList?

[Zilla707]

Hello, I have done some java, but I mostly do python3, and in python3 you can add a function to a list:

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>>> def test():
	print('Test')
	
>>> testList = []
>>> testList.append(test)
>>> testList[0]()
Test

So my question is: is there a way to do this, (or something like it), in java?

[clicky]

Java is very versatile object oriented language that can do many things and falls in very similar category as Python.

So, answer is: yes.

All you have to do now is to learn it. Internet is full of resources, examples and sites where you can even learn it online, do online courses and such.

[knute]

It's a little more complicated in Java.

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import java.util.*;
import java.util.function.*;

public class SSCCE {  // simple self contained compilable example
    public static void main(String... args) {
        // returns the argument unchanged
        UnaryOperator<String> u1 = UnaryOperator.identity();
        // returns the argument changed to lower case
        UnaryOperator<String> u2 = String::toLowerCase;
        // returns the argument's characters reversed
        UnaryOperator<String> u3 = f -> {
            return new StringBuffer(f).reverse().toString();
        };
        // returns the argument's characters reversed and then to lower case
        Function<String,String> u4 = u3.andThen(u2);  // or .compose

        // creates a list to hold functions
        List<Function<String,String>> list = new ArrayList<>();

        // add the functions to the list
        list.add(u1);
        list.add(u2);
        list.add(u3);
        list.add(u4);

        // apply the functions to the arguments
        System.out.print(list.get(0).apply("Hello"));
        System.out.println(list.get(1).apply(" WORLD!"));
        System.out.println(list.get(2).apply("SRETTEL EHT ESREVER"));
        System.out.println(list.get(3).apply(
         "ESAC REWOL OT SRETTEL EHT ESREVER"));
    }
}

C:\Users\Knute>java SSCCE.java
Hello world!
REVERSE THE LETTERS
reverse the letters to lower case

[Zilla707]

Thanks, I still don't know very much about java, (at least in relation to python), but that's very helpful.

[DamienIvy]

What I can understand you want to append a value to the List using python code.

In Java , you can append the value to the ArrayList using add() method of ArrayList class.

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ArrayList<String> arrlist = new ArrayList<String>();
arrlist.add("test");
System.out.println(arrlist);
 

Reference:
https://javahungry.blogspot.com/2017/10 ... ample.html

[aryank4564]

This is a pretty clear example of how to add data to ArrayList in python. However, if you want to learn how to append data into the ArrayList in Java. Just see the below code

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ArrayList<String> arrayList = new ArrayList<>();
arrayList.add("Object 1");
arrayList.add("Object 2");
System.out.println(arrayList); 

See Reference : https://www.java8net.com/2020/02/arraylist-in-java.html