AP Com Sci Chapter 2 Lab Review

// ***************************************************************
// StringManips.java
// Test several methods for manipulating String objects
// ***************************************************************

import java.util.Scanner;

public class StringManips
public static void main (String[] args)
//Declaring scanner object
Scanner scan = new Scanner (System.in);

//All the var declared and shows the phrase being manipulated
String phrase = “This is a String test.”;
int phraseLength; // number of chars in the phrase String
int middleIndex; // index of the middle char in the String
String middle3; //the middle three characters of the string
String firstHalf; // first half of the phrase String
String secondHalf; // second half of the phrase String
String switchedPhrase; //a new phrase w/ orig halves switched
String city, state; //var to hold city and state input

// compute the length and middle index of the phrase
phraseLength = phrase.length();
middleIndex = phraseLength / 2;

// get the substring for each half of the phrase
firstHalf = phrase.substring(0, middleIndex);
secondHalf = phrase.substring(middleIndex);

// get the substring for the middle three characters of the phrase
middle3 = phrase.substring(middleIndex – 1, middleIndex + 2);

//concat first half onto the end of second half
switchedPhrase = secondHalf.concat(firstHalf);
// replace all spaces in switchedphrase to astericks
switchedPhrase = switchedPhrase.replace (‘ ‘, ‘*’);

//assigning appropriate input to var city and state
System.out.println (“Please enter your city.”);
city = scan.nextLine();
System.out.println (“Please enter your state.”);
state = scan.nextLine();

//Modifying city and state input
state = state.toUpperCase();
city = city.toLowerCase();

// print information about the phrase
System.out.println (“Original phrase: “ + phrase);
System.out.println (“Length of the phrase: “ + phraseLength + ” characters”);
System.out.println (“Index of the middle: “ + middleIndex);
System.out.println (“Character at the middle index: “ +                                                                                            phrase.charAt(middleIndex));
System.out.println (“Switched phrase: “ + switchedPhrase);
System.out.println (“Middle three character: “ + middle3);
System.out.println (state.concat(city.concat(state)));

Notice that when I instantiated the String phrase, I didn’t have to use the new operator. This is a shortcut for creating new String objects only. You can skip the new operator and go straight to assigning a string to the object. When creating instances of other types of objects, you need to always use the new operator.

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