java 课后答案09reviewStringTextIO.docVIP

Chapter 9 Strings and Text I/O 1. s1 == s2 = true s2 == s3 = false s1.equals(s2) = true s2.equals(s3) = true pareTo(s2) = 0 pareTo(s3) = 0 s1 == s4 = true s1.charAt(0) = W s1.indexOf(j) = -1 s1.indexOf(to) = 8 s1.lastIndexOf(a) = 14 s1.lastIndexOf(o, 15) = 9 s1.length() = 16 s1.substring(5) = me to Java! s1.substring(5, 11) = me to s1.startsWith(Wel) = true s1.endsWith(Java) = true s1.toLowerCase() = welcome to java! s1.toUpperCase()= WELCOME TO JAVA! Welcome .trim() = Welcome s1.replace(o, T) = WelcTme tT Java! s1.replaceAll(o, T) = WelcTme tT Java! s1.replaceFirst(o, T) = WelcTme tT Java! s1.toCharArray() returns an array of characters consisting of W, e, l, c, o, m, e, , t, o, , J, a, v, a (Note that none of the operation causes the contents of a string to change) 2. String s = new String(new string); Answer: Correct String s3 = s1 + s2; Answer: Correct String s3 = s1 - s2; Answer: Incorrect s1 == s2 Answer: Correct s1 = s2 Answer: Incorrect pareTo(s2); Answer: Correct int i = s1.length(); Answer: Correct char c = s1(0); Answer: Incorrect char c = s1.charAt(s1.length()); Answer: Incorrect : its out of bounds, even if the preceding problem is fixed. The output is Welcome to Java Welcabcme tabc Java Hint: No method in the String class can change the content of the string. String is an immutable class. Check whether s1 is equal to s2 and assign the result to a Boolean variable isEqual. boolean isEqual = s1.equals(s2); Check whether s1 is equal to s2 ignoring case and assign the result to a Boolean variable isEqual. boolean isEqual = s1.equalsIgnoreCase(s2); Compare s1 with s2 and assign the result to an int variable x. int x = pareTo(s2); Compare s1 with s2 ignoring case and assign the result to an int variable x. int x = pareToIgnoreCase(s2); Check whether s1 has prefix AAA and assign the result to a Boolean variable b. boolean b = s1.startsWith(AAA); Check whether s1 has suffix AAA and assign the result to a Boolean variab