unit1_开发工具和Java语言介绍

版本控制系统：

github：私有化收费
bitbucket：免费但需要翻墙
oschina.net coding.net

svn:方便控制权限，各个目录的访问。也是一种版本控制系统。
牛客网、阿里巴巴、人人网等都使用svn。

开始

java 语言
intelli idea 工具
maven 相关库依赖的工具

语法

public static void print(int index, Object object){
	System.out.printlnI(String.format("{%d}, %s", index, object.toString()));
}
public static void main(String[] args){
	print(1, "Hello World");
}
结果：
{1}, Hello World

注释：//; /* /; /* /; 单行，多行，Java Doc

运算

public static void demoOperation(){
	print(1, 5+2);
	print(2, 5-2);
	print(3, 5*2);
	print(4, 5/2);
	print(5, 5%2);
	print(6, 5<<2);
	print(7, 5>>2);
	print(8, 5|2);
	print(9, 5^2);
	print(10, 5==2);
	print(11, 5!=2);
}

变量

int a = 11;
double b = 2.2f;
a += 2;
print(14, a);

字符串

String str = "Hello World";
print(1, str.indexOf('e')); //判断某一个字符串中是否存在e，返回位置(不存在返回-1)
print(2, str.charAt(3)); //返回l
print(3, str.codePointAt(1)); //101；ASCLL码
print(4, str.compareToIgnoreCase("HELLO WORLD")); //0; 相同的
print(5, str.compareTo("hello vorld")); // 1；比v大的距离（二进制中的）
print(6. str.compareTo("hello xorld")); // -1；
print(7, str.contains("hello")); //true
print(8, str.concat("!!!")); 
print(9, str.toUpperCase());
print(10, str.endsWith("world")); //true
print(11, str.startsWith("hell")); //true
print(12, str.replace('o', 'e'));
print(13, str.replaceAll("o|l", "a"));
print(14, str.replaceAll("hello", "hi"));
print(15, str+str);

不产生新的对象的基础上，对所有类型进行append的操作

StringBuilder sb = new StringBuilder(); // 线程不安全
sb.append('x ');
sb.append(1.3);
sb.append("a");
sb.append(true);
print(16, sb.toString()); //x 1.3atrue

控制流

public static void demoControlFlow(){
	int a = 3;
	int target = a==2? 1:3;
	if(a == 2){
		target = 1;
	}else{
		target = 3;
	}
}

String grade = "B";
switch(grade){
	case "A":
		print(3, ">80");
		break;
	case "B":
		break;
		print(2, "60-80");
	case "C":
		print(1, "<60");
		break;
	default:
		print(6, "未知");
		break;
}

for(int i=0;i<4;i++){
	print(7, i);
}

while(score<100){
	print(8, score);
	score+=20;
}

数据结构

ArrayList：可变数组

public static void demoList(){
	List<String> strList = new ArrayList<String>(10);
	for(int i=0; i<4; i++){
		strList.add(String.valueOf(i*i));
	}
	print(1, strList);

	List<String> strListB = new ArrayList<String>();
	for(int i=0; i<4; i++){
		strList.add(String.valueOf(i));
	}
	strList.addAll(strListB); //将两个列表合并
	print(2, strList);
	strList.remove(0);
	print(3, strList);
	strList.remove(String.valueOf(1));
	print(4, strList);
	print(5, strList.get(1));

	Collections.reverse(strList);
	print(6, strList);
	
	Collections.sort(strList);
	print(7, strList);
	Collections.sort(strList, new Comparator<String>(){
		@Override
		public int compare(String o1, String o2){
			return o1.compareTo(o2);
		}
	})
	print(8, strList);

	for(String obj:strList){
		print(9, obj);
	}
	for(int i=0;i<strList.size();i++){
		print(10, strList.get(i));
	}
	
	int[] array = new int[]{1, 2, 3};
	print(11, array[1]);
}
public static void main(String[] args){
	demoList();
}

HashMap

public static void demoMapTable(){
	Map<String, String> map = new HashMap<String, String>();
	for(int i=0;i<4;i++){
		map.put(String.valueOf(i), String.valueOf(i*i));
	}
	print(1, map);	
	
	// map<int, int>::iterator it = map.begin();
	for(Map.Entry<String, String> entry : map.entrySet()){
		print(2, entry.getKey() + "|" + entry.getValue());
	}
	print(3, map.values()); //[0,1,4,9]
	print(4, map.keySet()); //[0,1,2,3]
	print(5, map.get("3")); //9
	print(6, map.containsKey("A")); //false
	map.replace("3", "27");
	print(7, map.get("3")); //27
}

Set

public static void demoSet(){
	Set<String> strSet = new HashSet<String>();
	for(int i=0;i<3;i++){
		strSet.add(String.valueOf(i));
	}
	print(1, strSet); //[0,1,2]
	strSet.remove(String.valueOf(1));
	print(2, strSet); //[0,2]
	print(3, strSet.contains(String.valueOf(1))); //false
	print(4, strSet.isEmpty()); //false
	print(5, strSet.size()); //2

	strSet.addAll(Arrays.asList(new String[] {"A", "B", "C"}))
	print(6, strSet);

	for (String value: strSet){
		print(7, value);
	}
}

异常

public static void demoException(){
	try{
		int k = 2;
		k = k/0;
		// xxxxx
	}catch{
		print(2, e.getMessage());
	}finally{
		print(3, "finally");
	}
}
// {2}, / by zero
// {3}, finally

面向对象

封装

public interface Talking{
	void say();
}

public class Animal implements Talking{
	private String name;
	private int age;
	
	public Animal(String name, int age){
		this.name = name;
		this.age = age;
	}
	
	@Override
	public void say(){
		System.out.print(name + "Animal Say");
	}
	
	public static void demo00(){
		Animal a = new Animal("jim", 1);
		a.say();
	}
	public static void main(String[] args){
		demo00();
	}
}

继承

public class Human extends Animal{
	private String country;
	public Human(String name, int age, String country){
		super(name, age);
		this.country = country;
	}
	@Override
	public void say(){
		System.out.print("This is Human from" + country);
	}
}

多态

同一个接口，有不同的实现类。不关心这些实现类

随机数

public static void demoFunction(){
	Random random = new Random();
	// nextInt = 2
	random.setSeed(1);
	print(1, random.nextInt(1000)); //0-1000的一个随机数
	print(2, random.nextFloat());

	List<Integer> array = Arrays.asList(new Integer[]{1, 2, 3, 4, 5});
	Collections.shuffle(array); //随机打乱
	print(3, array);

	Date date = new Date();
	print(4, date);
	print(5, date.getTime()); //1970年至今毫秒数

	DateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
	print(6, df.format(date));

	print(7, UUID.randomUUID()); //随机字符串
	print(8, Math.log(10));
	print(9, Math.min(3, 10));
	print(10, Math.max(3, 10));
	print(11, Math.ceil(2.2));
	print(9, Math.floor(2.2));
}

作业

 1.开发环境搭建
 2.IntelliJ菜单里每个按钮的使用熟悉
 3.Java基础语法练习
 4.Java容器类库练习
 5.随机数、时间等常用类
 6.练习代码提交到Bitbucket
 7.时间的自己练习