摘要：
Java File Handling The File class from the java.io package, allows us to work with files. import java.io.File; // Import the File class File myObj = n 阅读全文
摘要：
import java.util.ArrayList; public class Main { public static void main(String[] args) { ArrayList<Integer> numbers = new ArrayList<Integer>(); number 阅读全文
摘要：
Threads allows a program to operate more efficiently by doing multiple things at the same time. Creating a Thread There are two ways to create a threa 阅读全文
摘要：
Pattern Class - Defines a pattern (to be used in a search) Matcher Class - Used to search for the pattern PatternSyntaxException Class - Indicates syn 阅读全文
摘要：
try and catch 确切的说这应该是Exception。因为Error是指Java虚拟机无法解决的严重问题，如stack溢出，堆溢出... Use try and catch: 可以写多个catch来捕捉不同的exception类型 public class Main { public st 阅读全文
摘要：
Wrapper classes provide a way to use primitive data types (int, boolean, etc..) as objects. Primitive Data TypeWrapper Class byte Byte short Short int 阅读全文
摘要：
An Iterator is an object that can be used to loop through collections, like ArrayList and HashSet. // Import the ArrayList class and the Iterator clas 阅读全文
摘要：
A HashSet is a collection of items where every item is unique, and it is found in the java.util package: import java.util.HashSet; // Import the HashS 阅读全文
摘要：
A HashMap however, store items in "key/value" pairs, and you can access them by an index of another type (e.g. a String). Create a HashMap object call 阅读全文
摘要：
The LinkedList class is almost identical to the ArrayList: import java.util.LinkedList; public class Main { public static void main(String[] args) { L 阅读全文