weixin_49321034的博客

控制台中输出结果：文件夹中输出结果：

ArrayList<personList> list = new ArrayList<>(); list.add(new personList("张三",18)); list.add(new personList("赵四",18)); list.add(new personList("王五",18)); ObjectOutputStream oos = new ObjectOutputStream(new Fil..

主函数 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("IO\\person.txt")); oos.writeObject(new person("迪丽热巴",18)); oos.close();类方法public class person implements Serializable { private String name; privat

OutputStreamWriter ow = new OutputStreamWriter(new FileOutputStream("IO\\utf-8.txt"),"UTF-8"); ow.write("我爱你"); ow.flush(); ow.close();"UTF-8"声明调用的编码，不写也默认为UTF-8输出结果：为中文IDea中默认编码为UTF-8..当将UTF-8改为GBK(中文编码)OutputStreamWriter ...

BufferedReader bis = new BufferedReader(new FileReader("IO\\出师表.txt")); BufferedWriter bos = new BufferedWriter(new FileWriter("IO\\出师表正序.txt")); HashMap<String,String> map = new HashMap<>(); String line; whi..

输入流 FileOutputStream fos = new FileOutputStream("IO\\a.txt"); BufferedOutputStream bos = new BufferedOutputStream(fos); bos.write("想你想到疯了".getBytes()); bos.flush();刷新，以便写入 bos.close();释放内存..输出流...

Properties prop = new Properties(); prop.setProperty("迪丽热巴","18"); prop.setProperty("马儿扎哈","21"); prop.setProperty("赵丽颖","31"); FileWriter fw = new FileWriter("IO\\a.txt"); prop.store(fw,"我爱你"); fw....

public static void main(String[] args){ FileWriter fw = null; try { fw = new FileWriter("IO1\\a",true); } catch (IOException e) { System.out.println(e); }finally { if(fw != null){ ...

FileInputStream fis = new FileInputStream("IO\\海尔恰饭.mp3"); FileOutputStream fos = new FileOutputStream("IO\\a1.mp3"); long s = System.currentTimeMillis(); byte[] bytes = new byte[1]; int len = 0; while ((le...

int len = 0; while ((len = fis.read()) != -1){ fis.read(); }逐一将文档中的字符转化为字节输出每识别一个字节光标往下移动一位识别到最后一位时输出-1.文件夹内容abc输出结果：97，98，99，...

..输出结果为：100ABCD该方法通过ASCII转换输入的字符整形输入负数时将会转化为中文输出结果为：100ABCDE烤紻E..从数组中输入部分字节..直接输入想要的字符串输出的字节数组为：[-26, -120, -111, -25, -120, -79, -28, -67, -96]文件夹中显示：我爱你...

主函数 public static void main(String[] args) { File f1 = new File("D:\\FA\\JAVAspace\\FightingLangOwner\\Demo\\src\\DemoFile"); getFileName(f1); }实现类 public static void getFileName(File f1){ 方法① 简化前： File

过滤器原理 public static void main(String[] args) { File f1 = new File("D:\\FA\\JAVAspace\\FightingLangOwner\\Demo\\src\\DemoFile"); getFileName(f1); } public static void getFileName(File f1){ File[] arrFile = f1.listFil

public static void main(String[] args) { File f1 = new File("D:\\FA\\JAVAspace\\FightingLangOwner\\Demo\\src\\DemoFile"); getFileName(f1); } public static void getFileName(File f1){ File[] arrFile = f1.listFiles(); ...

list File f1 = new File("D:\\FA\\JAVAspace\\FightingLangOwner\\Demo\\src\\DemoFile"); String[] arr = f1.list(); for (String a : arr) { System.out.println(a); }输出结果：..listFilesFile f1 = new File("D:\\FA\\JA

createNewFile File file = new File("D:\\FA\\JAVAspace\\FightingLangOwner\\Demo\\src\\DemoFile\\123.txt"); boolean f1 = file.createNewFile(); System.out.println(f1);在绝对路径下创建一个文件，并返回布尔值..mkdirnew File("src\\DemoFile\\111").mkdir

Person[] arr = { new Person("杨颖",28), new Person("赫本",99), new Person("明日花",25) }; /*Arrays.sort(arr,new Comparator<Person>() { @Override public int comp...

Object obj = new Object(); new Thread(){ @Override public void run() { while(true){ synchronized (obj){ System.out.println("告知老板包子数量和种类"); ...

创建对象Lock l = new ReentrantLock();Lock是ReentrantLock接口的实现类 l.lock(); if(ticket > 0){ try{ Thread.sleep(10); System.out.println(Thread.currentThread().getName() + "-->正在卖出第" + ticket-- +"张票");

首先创建锁对象Object obj = new Object();将锁对象放入锁方法中中去synchronized (obj){ System.out.println(name + "正在卖" + paper.remove(i++) + "号票"); }当多个线程同时执行时先拿到锁对象的线程可以进入同步代码块中去执行代码没有抢到锁对象的线程则阻塞停止。.当一个线程运行完毕之后，归还锁对象下一个下称抢到则运行.这样做的好处是保证

String word = "生而为人，我很抱歉"; char[] ch = word.toCharArray(); for(char c : ch){ System.out.print(c); try{ Thread.sleep(1000); }catch (InterruptedException e){ e.pri..

创建类方法getname@Override public void run(){ String name = getName(); System.out.println(name);}主方法运行 MyThread mt = new MyThread(); mt.start(); new MyThread().start(); new MyThread().start();最后输出结果..类方法中另

主函数 MyThread mt = new MyThread(); mt.start(); for(int i =0; i<20 ; i++){ System.out.println("main:" + i); }MyThread子类public class MyThread extends Thread { public MyThread() { } public void

public class Demo03 { static String[] usernames = {"张三", "李四", "王五"}; public static void main(String[] args) throws RegisterException { String logicname = new Scanner(System.in).next(); checkUsername(logicname); } public

of创建一个不可修改的集合想往里注入元素时，会报错..往Set和Map中初始化元素有重复时，也会报错.同样的用of不能再添加其他元素

LinkedHashMap LinkedHashMap<String,Integer> link = new LinkedHashMap<>(); link.put("a", 11); link.put("b", 22); link.put("d", 44); link.put("a", 55); link.put("c", 33); System.out

Map<person,String> map = new HashMap<>(); map.put(new person("迪丽热奶",18), "上海"); map.put(new person("杨颖",20), "西安"); map.put(new person("古力娜扎",21), "新疆"); map.put(new person("赵丽颖",23), "成都"); map.p...

map.put("迪丽热巴",18); map.put("杨颖",20); map.put("古力娜扎",21); map.put("赵丽颖",23); Set<String> set = map.keySet(); Iterator<String> it = set.iterator(); while(it.hasNext()){ String ...

put(K key, V value)返回值：v存储键值对的时候，key不重复，返回值v是null存储键值对的时候，key重复，会使用新的value替换map中重复的value，返回被替换的value值 Map<String,String> map = new HashMap<>(); String v1 = map.put("李晨","范冰冰1"); System.out.println(v1); String v2

ArrayList<String> list = new ArrayList<>(); Collections.addAll(list, "a","b","c","d","e","f"); System.out.println(list); Collections.shuffle(list); System.out.println(list);shuffle打乱数组中元素的顺序addAll往数组...

可变参数底层是一个数组根据传递参数个数不同，会创建不同长度的数组，来存储参数 public static void main(String[] args) { int i = add(10,20,30,40,50,60,70); System.out.println(i); } public static int add(int...arr){ System.out.println(arr); System.out.

ArrayList<Object> list01 = new ArrayList<>(); list01.add("a"); list01.add(123); list01.add(true); printArray(list01); } public static void printArray(ArrayList<?> list){ Iterator&l...

主函数 GennerMethod.method(true); GennerMethod.method(123); GennerMethod.method("abc");方法 public static <S> void method(S s){ System.out.println(s); }<S>为自定义的泛型，可以传进来任何类型的数据类型...

ArrayList<String> list = new ArrayList<>(); list.add("aaa"); list.add("ccc"); list.add("ddd"); list.add("eee"); for(String s:list){ System.out.println(s); }int[] arr = {1,2,3,4...

Collection<String> coll = new ArrayList<>(); coll.add("路飞"); coll.add("索隆"); coll.add("娜美"); coll.add("香吉士"); coll.add("乔巴"); coll.add("罗宾"); Iterator<String> it = coll.ite...

普通的创建字符串，每当创建一个的时候，就要多处一个内存空间，效率低下..而StringBuider相当于一个vector容器，只占用一个内存空间，可以无限往里添加字符，当空间不足时会自动扩容..常用方法介绍append str1.append("asd"); str1.append(132); str1.append(true);可以添加任何数据类型输出结果...

int[] arr1 = {1,2,3,4}; int[] arr2 = {5,6,7,8,9}; System.arraycopy(arr1,0,arr2,0,2); System.out.println(Arrays.toString(arr2));输出结果：

System.out.print("请以yyyy-MM-dd格式输入您的出生年月："); String birth = new Scanner(System.in).next(); long birthDate = new SimpleDateFormat("yyyy-MM-dd").parse(birth).getTime(); long difTime = new Date().getTime() - birthDate; ...

父类public class Phone { public int num = 30;}子类public class person extends Phone{ private int num = 20; public void method(){ int num = 10; System.out.println(num); //10 System.out.println(this.num); //20

System.out.print(Math.abs(-2.5)); //2.5Math.abs获取绝对值..System.out.print(Math.ceil(3.1)); //4.0Math.ceil向上取整数..System.out.print(Math.floor(3.9)); //3.0Math.floor向下取整数..System.out.print(Math.round(3.6)); //4.0Math.round四舍五入..Math.PI取圆周率.