比较存储在ArrayList中的字符串元素

Question

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.

Answer 1

use list.contains(Object o) to check if list contains String . For comparing of String use "a".equals(list.get(0)) method.

Answer 2

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)

Answer 3

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
}

Answer 4

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