某些值为空字符串时的串联字符串

let str1 = "Hello";
let str2 = "";
let str3 = "World";

let result = "";
if (str1 !== "") {
  result += str1;
}
if (str2 !== "") {
  result += str2;
}
if (str3 !== "") {
  result += str3;
}

console.log(result); // 输出：HelloWorld

str1 = "Hello"
str2 = ""
str3 = "World"

result = "{}{}{}".format(str1, str2, str3)
print(result)  # 输出：HelloWorld

String str1 = "Hello";
String str2 = "";
String str3 = "World";

StringBuilder sb = new StringBuilder();
sb.append(str1);
sb.append(str2);
sb.append(str3);

String result = sb.toString();
System.out.println(result); // 输出：HelloWorld