Java

public class Sample {
  public static void func(Action<String> a) { 
    a.apply('Hello');
  }
  public static void main(String[] args) {
    Sample.func(s -> System.out.println(s));
    // 複数行の場合
    Sample.func(s -> { 
      System.out.println(s)
      System.out.println(s)
    });
  }
}

JavaScript

const func = (callback) => {
  callback('Hello');
};

func((s) => console.log(s));
// 複数行の場合
func((s) => {
  console.log(s)
  console.log(s)
});

Ruby

def func
  yield 'Hello'
end

func { |s| p s }
# 複数業行の場合
func do |s|
  console.log(s)
  console.log(s)
end
# {}でも動作するがdo~endがベター