It is an array of Object. From the source:
http://hg.openjdk.java.net/jdk7/jdk7/jdk/file/tip/src/share/classes/java/util/ArrayList.java
private transient Object[] elementData;
It is an array of Object. From the source:
http://hg.openjdk.java.net/jdk7/jdk7/jdk/file/tip/src/share/classes/java/util/ArrayList.java
private transient Object[] elementData;