如何在java中连接两行？

String line1 = "Hello";
String line2 = "World";
String result = line1 + line2;
System.out.println(result);

HelloWorld

String line1 = "Hello";
String line2 = "World";
StringBuilder sb = new StringBuilder();
sb.append(line1).append(" ").append(line2);
String result = sb.toString();
System.out.println(result);

Hello World