String str1 = "Hello Java的长度:10";
final String s1 = "Hello ";
String str2 = s1+"Java"+"的长度:10";
System.out.println(str1==str2);
final int len = 10;
String str3 = s1+"Java"+"的长度:"+len;
System.out.println(str1==str3);
请问,两个输出结果是啥,为何?

String str1 = "Hello Java的长度:10";
final String s1 = "Hello ";
String str2 = s1+"Java"+"的长度:10";
System.out.println(str1==str2);
final int len = 10;
String str3 = s1+"Java"+"的长度:"+len;
System.out.println(str1==str3);
请问,两个输出结果是啥,为何?