input: Write a python function to filter strings that start with "java" from a given list.
  assert filter_java(["python", "c++", "java", "java-script"]) == ["java", "java-script"]
  assert filter_java(["javascript", "c#", "javafx", "ruby"]) == ["javascript", "javafx"]
  assert filter_java(["html", "css", "java"]) == ["java"]
output: def filter_java(strings):
      return [s for s in strings if s.startswith("java")]