Do you think that the following is correct?
str1.length() = 12 ; // change the length of str1
No. The left side of an assignment statement must be a variable.
It has been a long time since you have had some blanks to fill in. I'm sure that you have missed them. Here is a program that will:
String objectsString will hold the characters "Green eggs"String will hold the characters " and ham" 
class StringTester
{
  public static void main ( String[] args )
  {
    String str1;   // a reference to a String object.
    String str2;   // a reference to a second String object.
    int len1, len2;    // the length of str1 and the length of str2
    str1  =  ; // create the first String
    str2  =  ; // create the second String
    len1  = str1.length();    // get the length of the first string
    len2  =  . ;    // get the length of the second string
    System.out.println("The combined length of both strings is " +
         + " characters" );
  }
}
Fill in the blanks of the program.