2.JDK7新特性

• 支持二进制字面量
• 数字字面量可以出现下划线
• switch 语句支持符串
• 泛型简化,菱形泛型
• 异常的多个catch合并,每个异常之间使用或 “|”

• try-with-resources 语句

  支持二进制字面量

   @Test
   public void demo1(){
       System.out.println(0b110);//6
   }

  数字字面量可以出现下划线

   @Test
   public void demo2(){
       System.out.println(0b100_100);//36
       System.out.println(100_100);//100100
   }

  switch 语句支持符串

   @Test
   public void demo3(){
       String str = "2";
       switch (str){
           case "1":
               System.out.println("1");
               break;
           case "2":
               System.out.println("2");
               break;
           case "3":
               System.out.println("3");
               break;
           default:
               System.out.println("其他");
               break;
       }
  
   }
  

  泛型简化,菱形泛型

   @Test
   public void demo4(){
       //JDK1.7之前
       Map<String, Object> map = new HashMap<String, Object>();
       List<Object> list = new ArrayList<Object>();
  
       //JDK1.7起
       Map<String, Object> map2 = new HashMap<>();
       List<Object> list2 = new ArrayList<>();
  
   }
  

  异常的多个catch合并,每个异常之间使用或 “|”

  ```java @Test public void demo5(){

   try {
       FileInputStream fis = new FileInputStream("");
       Thread.sleep(1000);
   } catch (FileNotFoundException | InterruptedException e) {
       e.printStackTrace();
   }
  

}

<a name="C0cMe"></a>
### try-with-resources 语句
try-with-resources 语句：自动关闭流<br />开发中一般不用

```java
 try(...){}

    @Test
    public void demo6() throws IOException {

        //在try()中书写的对象，都需要实现AutoCloseable接口
        try(
                FileInputStream fis = new FileInputStream("input.txt");
                FileOutputStream fos = new FileOutputStream("output.txt");
                MyClose mc = new MyClose();
        ){
            int b;
            while((b = fis.read()) != -1) {
                fos.write(b);
            }
        }
    }

class MyClose implements AutoCloseable {

    @Override
    public void close() {
        System.out.println("我关了");
    }
}