本文主要是介绍unit1_开发工具和Java语言介绍，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
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>(){@Overridepublic 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")); //9print(6, map.containsKey("A")); //falsemap.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))); //falseprint(4, strSet.isEmpty()); //falseprint(5, strSet.size()); //2strSet.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;}@Overridepublic 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;}@Overridepublic 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 = 2random.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Bitbucket7.时间的自己练习
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