Four Java mini-puzzles

a : analyze the following requirements and implement them with code

1. defining a List Collection, depositing multiple strings

2. Delete the string "Def" in the collection

3. then iterate through the collection elements and output

1 Importjava.util.ArrayList;2 Importjava.util.List;3 4  Public classTopic15 {6      Public Static voidMain (string[] args) {7Arraylist<string> ArrayList =NewArraylist<>();8Arraylist.add ("DSFSD");9Arraylist.add ("Def");TenArraylist.add ("GHDH"); OneArraylist.add ("FDGD"); AArraylist.add ("QEWR"); -          for(inti = 0; I < arraylist.size (); i++) { -             if(Arraylist.get (i) = = "Def"){ theArraylist.remove ("Def"); -             } -         } - System.out.println (arrayList); +     } -}

two : analyze the following requirements and implement them with code

1. generate a random integer between 1 and Cannot be duplicated ), in a List Collection

2. then use the iterator and the enhanced for Loop to iterate through the collection elements and output

3. for example, the following:

1 Importjava.util.ArrayList;2 ImportJava.util.HashSet;3 ImportJava.util.Random;4 5  Public classTopic2 {6      Public Static voidMain (string[] args) {7Arraylist<integer> ArrayList =NewArraylist<>();8Hashset<integer> set =NewHashset<>();9Random RA =NewRandom ();Ten          while(Set.size () <=10){ One             intnum = ra.nextint (100) +1; A set.add (num); -         } - Arraylist.addall (set); the System.out.println (arrayList); -     } -}

three : analyze the following requirements and implement them with code

1. defining a List Collection, depositing multiple strings

2. Delete The string containing the 0-9 number in the collection element string ( as long as the string contains 0-9 You need to delete this entire string )

3. then iterate through the collection elements and output

1 Importjava.util.ArrayList;2 ImportJava.util.Iterator;3 4  Public classTOPIC3 {5      Public Static voidMain (string[] args) {6         //1. Defining a list collection, depositing multiple strings7Arraylist<string> ArrayList =NewArraylist<>();8Arraylist.add ("Dfsd5");9Arraylist.add ("SDGD");TenArraylist.add ("FGDSG"); OneArraylist.add ("f1ds"); A          for(inti = Arraylist.size ()-1; i>=0; i--) { -             if(Methoddelete (Arraylist.get (i)) = =true){ - Arraylist.remove (i); the             } -         } -Iterator<string> it =arraylist.iterator (); -          while(It.hasnext ()) { +System.out.print (It.next () + ""); -         } +  A         //3. Then iterate through the collection elements and output at     } -  -     //2. Delete the string containing 0-9 digits in the collection element string (as long as any number in the string contains 0-9 -      Public Static BooleanMethoddelete (String string) { -         Char[] Array =String.tochararray (); -          for(inti = 0; i < Array.Length; i++) { in             if(array[i]>=48 && array[i]<=57){ -                 return true; to             } +         } -         return false; the     } *}

Four : analyze the following requirements and implement them with code

1. count The occurrences of each word

2. the following string "If you want to change your fate I Think you must come to the dark horse to learn Java" ( with space interval )

3. printing format:

To=3

Think=1

you=2

1 ImportJava.util.HashMap;2 ImportJava.util.Map;3 ImportJava.util.Set;4 5  Public classTopic4 {6      Public Static voidMain (string[] args) {7String str = "If you want to change your fate I Think you must come to the dark horse to learn Java";8String strarr[] = Str.split ("");9        /*for (int i = 0; i < strarr.length; i++) {Ten System.out.print (strarr[i]+ ""); One         }*/ Ahashmap<string,integer> map =NewHashmap<>(); -          for(String s:strarr) { -           /*if (Map.containskey (s)) { the //Presence - Integer value = Map.get (s); - value++; - //Overwrite value value continuously + Map.put (s,value); -             } + else { A //does not exist at Map.put (s,1); -             }*/ -           //Map.put (C,map.containskey (c)? Map.get (c) +1:1); -Map.put (S,map.containskey (s)? Map.get (s) +1:1); -         } -set<map.entry<string, integer>> entryset =Map.entryset (); in          for(Map.entry<string, integer>Entry:entryset) { -System.out.println (Entry.getkey () + "=" +Entry.getvalue ()); to         } +     } -}

Five: Analyze the following requirements and implement them with code

2. define a norepeat () method that requires the element to be passed over the set

public static void Norepeat (List<string> al) {

Contains

}

1 Importjava.util.ArrayList;2 Importjava.util.List;3 4  Public classTOPIC5 {5      Public Static voidMain (string[] args) {6Arraylist<string> ArrayList =NewArraylist<>();7Arraylist.add ("SDGSDG1");8Arraylist.add ("SDGSDG");9Arraylist.add ("SDGSDG");TenArraylist.add ("SDGSDG1"); One norepeat (arrayList); A     } -      Public Static voidNorepeat (list<string>al) { -          for(inti = 0; I < al.size (); i++) { the             //The first element is removed if the subsequent elements are equal. -String first =Al.get (i); -              for(intJ =i+1;j<al.size (); j + +) -             { +                 if(First.equals (Al.get (j))) { -                     //If the following element is the same, delete the following element + Al.remove (j); A                    //j--; at                 } -             } -         } - System.out.println (AL); -     } -  in}

Four Java mini-puzzles