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Homework to practice ArrayList

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• Do question 3 in the AP Computer Science A 2021 free-response questions:

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• You can use the following Java class to help you write the answers in BlueJ and test them:

  public class MemberInfo { private String name; private int gradYear; private boolean hasGoodStanding; public MemberInfo(String n, int yr, boolean gs ) { name = n; gradYear = yr; hasGoodStanding = gs; } public int getGradYear() { return gradYear; } public boolean inGoodStanding() { return hasGoodStanding; } public String getName() { return name; } public String toString() { return name+" "+gradYear+" "+hasGoodStanding; } }

  import java.util.*; public class ClubMembers { private ArrayList memberList; public ClubMembers( ) { memberList = new ArrayList(); } public void addMembers( String[] names, int gradYear ) { // Write this method for part A } /* -------------------------------------------------------- WARNING: Removal is tricky, because when after call: arrayList.remove(i) a new arrayList element will be in spot i !! --------------------------------------------------------- */ public ArrayList removeMembers( int year ) { // Write this method for part B return null; // Statement added to prevent compile error // Remove it when you write this method } public void addMember( MemberInfo mem ) { memberList.add( mem ); } public String toString() { return memberList.toString(); } }

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  Use this Java program to test your answer to question A:

  public class TestA { public static void main(String[] args) { ClubMembers cm = new ClubMembers(); String[] names1 = {"James", "Mary"}; cm.addMembers( names1, 2015 ); System.out.println( cm ); String[] names2 = {"John", "Ann"}; cm.addMembers( names2, 2019 ); System.out.println( cm );*/ } }

  The correct answer is:

  [James 2015 true, Mary 2015 true] [James 2015 true, Mary 2015 true, John 2019 true, Ann 2019 true]

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  Use this Java program to test your answer to question B:

  public class TestB { public static void main(String[] args) { ClubMembers cm = new ClubMembers(); cm.addMember( new MemberInfo( "John", 2000, false ) ); cm.addMember( new MemberInfo( "Mary", 2005, true ) ); cm.addMember( new MemberInfo( "Jack", 2010, true ) ); cm.addMember( new MemberInfo( "Pete", 2014, false ) ); cm.addMember( new MemberInfo( "Anna", 2018, true ) ); cm.addMember( new MemberInfo( "Jake", 2019, false ) ); System.out.println( cm ); System.out.println( cm.removeMembers( 2017 ) ); System.out.println( cm ); } }

  The correct answer is:

  [John 2000 false, Mary 2005 true, Jack 2010 true, Pete 2014 false, Anna 2018 true, Jake 2019 false] [Mary 2005 true, Jack 2010 true] [Anna 2018 true, Jake 2019 false]