Java: Porting simple operations from Python to Java/ List Processing

Question

In Python I can do some simple stuff like:

# declare lists
A =["a","bnbnb"]
B = [1,2,3]
C = ['x'] + A    # (Simple Append)

# iterate over both lists
for x in [A,B,C]:  # (Create list of lists on the fly for for loops)
    do something to X[0]

And so on.

I am new to Java - and understand that arrays are fixed size, but lists and array lists arent. How would I mimic the above?

Here is my failed attempt

# declare lists
String[] A ={"a","bnbnb"}
String[] B = [1,2,3]
Stuck here C = ['x'] + A    (Simple Append)

# iterate over both lists
for x in [A,B,C]:  (Cant seem to do this either)
    # do something to X[0]

Using ArrayLists just kept making it more cumbersome - bet I am missing something obvious.

arshajii · Accepted Answer · 2013-08-16 20:12:35Z

2

You should use Lists instead:

List<String> A = Arrays.asList("a", "bnbnb");
List<String> B = Arrays.asList("1", "2", "3");

// you have to do this in two steps:
List<String> C = new ArrayList<String>(Arrays.asList("x"));
C.addAll(A);

// iteration:
for (List<String> x : Arrays.asList(A, B, C)) {
    // do something to x.get(0), analogous to x[0] in Python    
}

(See Arrays.asList())

answered Aug 16, 2013 at 20:12

arshajii

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2 Comments

pythOnometrist Over a year ago

Got it - The example on the link makes this clear - List<String> stooges = Arrays.asList("Larry", "Moe", "Curly");

pythOnometrist Over a year ago

And for [A,B,C] is the equivalent List<List<String>> D = Arrays.asList(A,B,C) ?

JNL · Accepted Answer · 2013-08-16 20:37:06Z

0

List would serve your purpose.

            String[] A ={"a","bnbnb"};
            String[] B = {"1","2","3"};
            List<String> C = new ArrayList<String>();

            C.add("X");
            Collections.addAll(C,A);

            System.out.print(C);

edited Aug 16, 2013 at 20:37

answered Aug 16, 2013 at 20:14

JNL

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1 Comment

arshajii Over a year ago

This isn't equivalent to the Python code. C should be a list of strings containing ["x","a","bnbnb"].

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