解释JAVA代码

Question

我需要一些帮助来解释从第5行到第9行的含义.谢谢

1. String words = "Rain Rain go away";

2. String mutation1, mutation2, mutation3, mutation4;

3. mutation1 = words.toUpperCase();

4. System.out.println ("** " + mutation1 + " Nursery Rhyme **");

5. mutation1 = words.concat ("\nCome again another day");

6. mutation2 = "Johnny Johnny wants to play";

7. mutation3 = mutation2.replace (mutation2.charAt(5), 'i');

8. mutation4 = mutation3.substring (7, 27);

9. System.out.print ("\'" + mutation1 + "\n" + mutation4 + "\'\n");

10. System.out.println ("Title length: " + words.length());

Answer 1

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