how can you take an ArrayList of chars and return all those elements from the ArrayList into a String

Question

This is the code for trying to answer my question. I'm kind of new with ArrayLists. I used a for loop trying to read every element from the Arraylist and put it in the new String "full" but this won't compile. I need some editing. I don't think this code properly works. I used .add so that I can try adding the elements from the String List to String full. This is what tried to do so far.

public void String() {

   ArrayList<Character> StringList = new ArrayList<Character>();
   String full;           
   for(int i = 0; i < arr.length; i++) {
       full.add(StringList[i]);
   }
   return full;
}

Answer 1

看一下StringBuilder类，特别是append方法： http : //docs.oracle.com/javase/1.5.0/docs/api/java/lang/StringBuilder.html

Answer 2

I suggest

• only use methods which are documented in Javadoc.
• Use StringBuilder to build Strings, not ArrayList of Characters.
• Don't call methods String and use camelCase for variables.
• Don't access ArrayList as if it were an array, use get(i)

Answer 3

One effective way is to append each character to the string:

String myString = "";
for (Character c : myList) {
    myString += c;
}

If myList.toString() gives: [a, b, c, d, e, f] , then myString gives: abcdef .

Answer 4

There is no .add(String) method in String class as far as i can remember.

But getting elements out of the ArrayList , is this what you are looking for?

StringList.get(i);

Answer 5

Normal way would be:

ArrayList<Character> StringList = new ArrayList<Character>();
StringList.add('H');
StringList.add('e');
StringList.add('l');
StringList.add('l');
StringList.add('o');
StringBuilder sb = new StringBuilder();
for(char c : StringList) sb.append(c);
System.out.println(sb.toString());

and here is another way to do it:

ArrayList<Character> StringList = new ArrayList<Character>();
StringList.add('H');
StringList.add('e');
StringList.add('l');
StringList.add('l');
StringList.add('o');
System.out.println(StringList.toString().replaceAll("[, \\[\\]]", ""));

OUTPUT:

Hello

Answer 6

1. Use lowerCamelCase as naming convention for name of variables and methods.
2. Use get(index) of ArrayList to retrieve elements. Don't use it like array. It will not work (eg StringList[i] is invalid use StringList.get(i))
3. Read the Java Doc
4. Always try to read and errors (if getting any)