1. switch 中使用字符串变量
public void testStringSwitch(String direction) { switch (direction) { case "up": y--; break; case "down": y++; break; case "left": x--; break; case "right": x++; break; default: System.out.println("Invalid direction!"); break; } }
2. 简化泛型对象创建
// Java 7 以前版本 Map<String,Map<String,int>>m=new HashMap<String, Map<String,int>>(); // Java 7 Map<String, Map<String, int>> m = new HashMap<>();
3. 多异常处理
try { Class a = Class.forName("wrongClassName"); Object instance = a.newInstance(); } catch (ClassNotFoundException | IllegalAccessException | InstantiationException ex) { System.out.println("Failed to create instance"); }
4. 资源的自动释放
try (BufferedReader in=new BufferedReader(new FileReader("test.txt"))) { String line = null; while ((line = in.readLine()) != null) { System.out.println(line); } } catch (IOException ex) { ex.printStackTrace(); }
5. 文件 IO API 的改进
下面是列出一个文件中所有行并打印的方法
List<String> lines = Files.readAllLines( FileSystems.getDefault().getPath("test.txt"), StandardCharsets.UTF_8); for (String line : lines) System.out.println(line);