java7的变化

最近一直用着java6,发现java7有如下变化

1.对collections的支持

 

List<String> list = new ArrayList<String>();
list.add("item");
String item = list.get(0);

Set<String> set = new HashSet<String>();
set.add("item");

Map<String, Integer> map = new HashMap<String, Integer>();
map.put("key", 1);
int value = map.get("key");

 现在你还可以：

 

List<String> list = ["item"];
String item = list[0];

Set<String> set = {"item"};

Map<String, Integer> map = {"key" : 1};
int value = map["key"];

 

 

2.自动资源管理

 

BufferedReader br = new BufferedReader(new FileReader(path));
try {
   return br.readLine();
} finally {
   br.close();
}

 becomes:

 

try (BufferedReader br = new BufferedReader(new FileReader(path)) {
   return br.readLine();
}

You can declare more than one resource to close:

try (
   InputStream in = new FileInputStream(src);
   OutputStream out = new FileOutputStream(dest))
{
 // code
}

 

3.对通用实例创建(diamond)的type引用进行了改进

 

 

Map<String, List<String>> anagrams = new HashMap<String, List<String>>();

 becomes:

 

Map<String, List<String>> anagrams = new HashMap<>();

4.数值可加下划线

 

int one_million = 1_000_000;

  

5.在switch中可使用string

 

String s = ...
switch(s) {
 case "quux":
    processQuux(s);
    // fall-through

  case "foo":
  case "bar":
    processFooOrBar(s);
    break;

  case "baz":
     processBaz(s);
    // fall-through

  default:
    processDefault(s);
    break;
}

 

6.二进制文字

 

int binary = 0b1001_1001;

  

7.简化了可变参数方法的调用

 

当程序员试图使用一个不可具体化的可变参数并调用一个*varargs* （可变）方法时，编辑器会生成一个“非安全操作”的警告。详情查看