书摘

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  • 你将读到的是北野武的出身、父母、兄弟和家庭的故事。
  • 但请放心，这绝非一个自我感觉良好的人写的那种“优良课外读物”。很喜欢这句←方便打标签的状态卡片
  • 相反，北野武用搞笑到甚至刻薄方式描绘这些人和事，让我们在笑与泪的交织中，看到真情和真实，看到那么多情、柔软的心。

数组

  • 声明语法

DataType[] name 或 DataType name[]。

  • 初始化语法

DataType[] name = { element1, element2, …elementn }。

  1. String[] strs = { "段", "光", "伟" };
  2. for (String item : strs) {
  3.      System.out.print(item);
  4. }
  6. StringBuffer sb = new StringBuffer().append("段").append("光")

枚举

  1. public final class Program {
  2.     public static void main(String[] args) {
  3.         System.out.println(State.ON);
  4.         System.out.println(State.OFF);
  6.         for (State item : State.values()) {
  7.             System.out.println(item);
  8.             System.out.println(State.valueOf(item.name()));
  9.         }
  10.     }
  11. }
  13. enum State {
  14.     ON(1), OFF(0);
  16.     int value = 1;
  18.     State(int value) {
  19.         this.value = value;
  20.     }
  21. }

类

  1. //简单的类
  2. class Point {
  3.     private int x = 0;
  4.     private int y = 0;
  6.     public Point(int x, int y) {
  7.         this.x = x;
  8.         this.y = y;
  9.     }
  11.     public Point(int x) {
  12.         this(x, x);
  13.     }
  15.     public String toString() {
  16.         return "(x:" + this.x + ",y:" + this.y + ")";
  17.         //  System.out.print(point);
  18.     }
  19. }
  21. //继承
  22. public class Program {
  24.     /**
  25.      * @param args
  26.      */
  27.     public static void main(String[] args) {
  28.         Animal animal = new Animal();
  29.         Animal dog = new Dog();
  31.         animal.say();
  32.         dog.say();
  34.         animal.eat(animal);
  35.         dog.eat(dog);
  37.         System.out.println(animal.info());
  38.         System.out.println(dog.info());
  39.     }
  40. }
  42. class Animal {
  43.     private String name = "Animal";
  45.     protected void say() {
  46.         System.out.println("Animal" + " " + this.name);
  47.     }
  49.     public void eat(Animal food) {
  50.         System.out.println("Animal eat " + food);
  51.     }
  53.     public Object info() {
  54.         return "Animal";
  55.     }
  57.     @Override
  58.     public String toString() {
  59.         return "Animal";
  60.     }
  61. }
  63. class Dog extends Animal {
  64.     private String name = "Dog";
  66.     @Override
  67.     public final void say() {
  68.         System.out.println("Dog" + " " + this.name);
  69.     }
  71.     @Override
  72.     public final void eat(Animal food) {
  73.         super.eat(food);
  75.         System.out.println("Dog eated");
  76.     }
  78.     @Override
  79.     public final String info() {
  80.         return "Dog";
  81.     }
  83.     @Override
  84.     public final String toString() {
  85.         return "Dog";
  86.     }
  87. }

异常

  1. public final class Program {
  2.     public static void main(String[] args) {
  3.         try {
  4.             test();
  5.         } catch (Exception e) {
  6.             System.out.println(e.getMessage());
  7.         }
  8.     }
  10.     public static void test() throws Exception {
  11.         throw new Exception("I am wrong!");
  12.     }
  13. }

泛型

泛型方法

  1. static <T> void puts(T msg) {
  2.         println(msg);
  3.     }
  5. static void println(Object msg) {
  6.     System.out.println("Object:" + msg);
  7. }
  9. static void println(String msg) {
  10.     System.out.println("String:" + msg);
  11. }
  13. puts("hello");
  14. Program.<String> puts("hello");

泛型类

  1. class TestGenericClass<T> {
  2.     T value;
  4.     void setValue(T value) {
  5.         this.value = value;
  6.     }
  7. }

Properties

写入文件

  1. public void writeProperties() {
  2.     Properties properties = new Properties();
  3.     OutputStream output = null;
  4.     try {
  5.         output = new FileOutputStream("config.properties");
  6.         properties.setProperty("url", "jdbc:mysql://localhost:3306/");
  7.         properties.setProperty("username", "root");
  8.         properties.setProperty("password", "root");
  9.         properties.setProperty("database", "users");//保存键值对到内存
  10.         properties.store(output, "Steven1997 modify" + new Date().toString());
  11.         // 保存键值对到文件中
  12.     } catch (IOException io) {
  13.         io.printStackTrace();
  14.     } finally {
  15.         if (output != null) {
  16.             try {
  17.                 output.close();
  18.             } catch (IOException e) {
  19.                 e.printStackTrace();
  20.             }
  21.         }
  22.     }
  23. }

加载

  1.  private static String basePath = "src/main/java/cn/habitdiary/prop.properties";
  2.  private static String path = "";
  4. public static String getPath1() {
  6.     try {
  7.         InputStream in = new BufferedInputStream(new FileInputStream(
  8.             new File(basePath)));
  9.         Properties prop = new Properties();
  11.         prop.load(in);
  13.         path = prop.getProperty("path");
  15.     } catch (FileNotFoundException e) {
  16.         System.out.println("properties文件路径书写有误，请检查！");
  17.         e.printStackTrace();
  18.     } catch (IOException e) {
  19.         e.printStackTrace();
  20.     }
  22.     return path;
  23. }
  24.     /**
  25.      * 二、 使用java.util.ResourceBundle类的getBundle()方法
  26.      * 注意：这个getBundle()方法的参数只能写成包路径+properties文件名，否则将抛异常
  27.      *
  28.      * @return
  29.      */
  30.     public static String getPath2() {
  31.         ResourceBundle rb = ResourceBundle
  32.                 .getBundle("cn/habitdiary/prop");
  33.         path = rb.getString("path");
  34.         return path;
  35.     }
  37.     /**
  38.      * 三、 使用java.util.PropertyResourceBundle类的构造函数
  39.      */
  40.     public static String getPath3() {
  41.         InputStream in;
  42.         try {
  43.             in = new BufferedInputStream(new FileInputStream(basePath));
  44.             ResourceBundle rb = new PropertyResourceBundle(in);
  45.             path = rb.getString("path");
  46.         } catch (FileNotFoundException e) {
  47.             // TODO Auto-generated catch block
  48.             e.printStackTrace();
  49.         } catch (IOException e) {
  50.             e.printStackTrace();
  51.         }
  52.         return path;
  53.     }
  54.     /**
  55.      * 四、 使用class变量的getResourceAsStream()方法
  56.      * 注意：getResourceAsStream()方法的参数按格式写到包路径+properties文件名+.后缀
  57.      */
  58.     public static String getPath4() {
  60.         InputStream in = LoadPropertiesFileUtil.class
  61.                 .getResourceAsStream("cn/habitdiary/prop.properties");
  63.         //五、使用class.getClassLoader()所得到的java.lang.ClassLoader的
  64.         InputStream in = LoadPropertiesFileUtil.class.getClassLoader()
  65.                 .getResourceAsStream("cn/habitdiary/prop.properties");
  67.         //六、 使用java.lang.ClassLoader类的getSystemResourceAsStream()静态方法
  68.         InputStream in = ClassLoader
  69.                 .getSystemResourceAsStream("cn/habitdiary/prop.properties");
  71.         Properties p = new Properties();
  72.         try {
  73.             p.load(in);
  74.             path = p.getProperty("path");
  75.         } catch (IOException e) {
  76.             e.printStackTrace();
  77.         }
  78.         return path;
  79.     }

遍历

  1. public static void printProp(Properties properties) {
  2.     System.out.println("---------（方式一）------------");
  3.     for (String key : properties.stringPropertyNames()) {
  4.         System.out.println(key + "=" + properties.getProperty(key));
  5.     }
  7.     System.out.println("---------（方式二）------------");
  8.     Set<Object> keys = properties.keySet();//返回属性key的集合
  9.     for (Object key : keys) {
  10.         System.out.println(key.toString() + "=" + properties.get(key));
  11.     }
  13.     System.out.println("---------（方式三）------------");
  14.     Set<Map.Entry<Object, Object>> entrySet = properties.entrySet();
  15.     //返回的属性键值对实体
  16.     for (Map.Entry<Object, Object> entry : entrySet) {
  17.         System.out.println(entry.getKey() + "=" + entry.getValue());
  18.     }
  20.     System.out.println("---------（方式四）------------");
  21.     Enumeration<?> e = properties.propertyNames();
  22.     while (e.hasMoreElements()) {
  23.         String key = (String) e.nextElement();
  24.         String value = properties.getProperty(key);
  25.         System.out.println(key + "=" + value);
  26.     }
  27. }