如何在java文本块中为变量值设置占位符

Question

如何将变量放入java文本块
就像

"""
{
  ...
  "someKey": "someValue",
  "date": "${LocalDate.now()}",
  ...
}
"""

Answer 1

可以在文本块中使用%s作为占位符

String str = """
{
...
"someKey": "someValue",
"date": %s,
...
}
"""

并用format替换它

String.format(str,LocalDate.now());

从jeps 355 docs

A cleaner alternative is to use String::replace or String::format, as follows:

String code = """
          public void print($type o) {
              System.out.println(Objects.toString(o));
          }
          """.replace("$type", type);

String code = String.format("""
          public void print(%s o) {
              System.out.println(Objects.toString(o));
          }
          """, type);

Another alternative involves the introduction of a new instance method, String::formatted, which could be used as follows:

String source = """
            public void print(%s object) {
                System.out.println(Objects.toString(object));
            }
            """.formatted(type);

注意：但是作为java-13文档的旁注String.formatted​被弃用，建议使用String.format(this, args).

This method is associated with text blocks, a preview language feature. Text blocks and/or this method may be changed or removed in a future release.