JDK 12-16 的重要更新
Switch Expressions（JDK 12预览，JDK 14正式）
// 传统switch
String result;
switch (day) {
case MONDAY:
case FRIDAY:
case SUNDAY:
result = "6 AM";
break;
case TUESDAY:
result = "7 AM";
break;
default:
result = "8 AM";
}
// 新的switch表达式
String result = switch (day) {
case MONDAY, FRIDAY, SUNDAY -> "6 AM";
case TUESDAY -> "7 AM";
default -> "8 AM";
};
Text Blocks（JDK 13预览，JDK 15正式）
String html = """
<html>
<body>
<p>Hello, world</p>
</body>
</html>
""";
