I have a string arraylist
ArrayList<String> data = new ArrayList<String>();
and I have stored string values inside. Now i want to do something like
data.get(0) == "a" // (need to compare)
How can I do? please help out.
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4 Answers
use list.contains(Object o) to check if list contains String. For comparing of String use "a".equals(list.get(0)) method.
2 Comments
lukastymo
Small point, I recommend "a".equals(list.get(0)) instead of list.get(0).equals("a")
michal.kreuzman
@smas You're right, it prevets potencial NullPointerException if null is in array list. I've edited it.
Here is some code to play with:
ArrayList<String> data = new ArrayList<String>();
data.add("a")
data.add("b")
data.add("c")
To check for equality:
data.get(0).equals("a"); // true
data.get(0).equals("b"); // false
To check for order:
data.get(0).compareTo("a"); // 0 (equal)
data.get(0).compareTo("b"); // -1 (a is less than b)
Comments
if(data.size() > 1 && "a".equals((String)data.get(0))) {
//do something
}
You should really use generics:
ArrayList<String> data = new ArrayList<String>();
if(data.size() > 1 && "a".equals(data.get(0))) {
//do something
}
Comments
So this is basic operations on Array and String. You have answer for your questions in Michal's post. But you can read some guide about it and do it by yourself
Oracle have nice tutorial about Arrays and for String you can find "String comparison" or just find method to compare in documentation String class in Java 1.6