Java comparing two arrays and checking if the First array is consecutive of the Second

Question

Long story short beginner programer here practicing with java. Right now I'm taking two arrays and I want to find out if int arrayA (7,14,21,28) is consecutive to int ArrayB meaning does arrayB have (7,14,21,28) consecutively within the array. If it is the boolean returns true if not it shall simply return false. Here is an example of my code.

 public class Harrison7aTest
 {
 public static void main(String [] args)
 {
  int[] arrayA = {7,14,21,28};
  int[] arrayB = {1,3,5,7,14,21,28,32};

 boolean result = false;

  for(int A = 0; A < arrayA.length - 1; A++)
  {
     for(int B = 0; B < arrayB.length - 1; B++)
     {


     }


  }

}
}

notice how in my first integer "arrayA" that it has the value 7,14,21,28. The second array "arrayB" has the value 1,3,5,7,14,21,28,32. Notice how in arrayB that it does in fact have the value 7,14,21,28 consecutively this would result in a true boolean — Cody Harrison
– Cody Harrison, Commented Apr 3, 2017 at 5:28
@RC. I'm reopening on the grounds that the OP's assignment is to write simple algorithm for doing this, rather than a slick one-liner. — Tim Biegeleisen
– Tim Biegeleisen, Commented Apr 3, 2017 at 5:33
@TimBiegeleisen that is correct, I am truly a beginner Java programmer so using for loops or nested for loops are really my only option with my current knowledge. — Cody Harrison
– Cody Harrison, Commented Apr 3, 2017 at 5:35

Raman Sahasi · Accepted Answer · 2017-04-03 05:59:09Z

3

You can convert them to string and make use of str.contains() method

String strArrA = Arrays.toString(arrayA);
String strArrB = Arrays.toString(arrayB);

//to strip square brackets that's comes with Arrays.toString
//for ex: Arrays.toString(arrayA); returns "[7, 14, 21, 28]"
//we want to convert it to "7, 14, 21, 28"
strArrA = strArrA.substring(1, strArrA.length()-1);

if (strArrB.contains(strArrA)) {
    System.out.println("true");
} else {
    System.out.println("false");
}

DEMO

edited Apr 3, 2017 at 5:59

answered Apr 3, 2017 at 5:28

Raman Sahasi

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Comments

Tim Biegeleisen · Accepted Answer · 2017-04-03 05:47:48Z

If you want to use the method would you would likely use in production as a Java engineer, then checkout the duplicate link given by @RC. or the answer by @Raman. For the purposes of your assignment, if you just want to answer the question using a single loop, then consider my answer. You can iterate once over the arrayB and check that the sequence of numbers contained within arrayA occurs, without interruption.

public static boolean containsConsecutive(int[] a, int[] b) {
    int aIndex = 0;
    for (int i=0; i < arrayB.length; i++) {
        if (aIndex != 0 && arrayB[i] != arrayA[aIndex]) {
            break;
        }
        else if (arrayB[i] == arrayA[aIndex]) {
            ++aIndex;
        }
    }

    return aIndex == arrayA.length;
}

public static void main(String[] args) {
    int[] a = {7,14,21,28,32};
    int[] b = {1,3,5,7,14,21,28,32};
    // true
    System.out.println(containsConsecutive(a, b));
    a = {7,14,21,28,32};
    b = {1,3,5,7,8,9,10,14,21,28,32};
    // false - sequence not in order
    System.out.println(containsConsecutive(a, b));
    a = {7,14,21,28,32,35};
    b = {1,3,5,7,14,21,28,32};
    // false - entire sequence in a not contained within b
    System.out.println(containsConsecutive(a, b));
}

Ashish Kumar · Accepted Answer · 2017-04-03 08:52:41Z

1

     int[] arrayA = {7,14,21,28};
     int[] arrayB = {1,3,5,7,14,21,28,32};
     boolean result=false;

     for(int i=0;i<arrayB.length;i++){

         if(arrayA[0] == arrayB[i]){
             for(int j=0;j<arrayA.length;j++){
                 if(arrayA[j] == arrayB[i+j]){
                     result=true;
                 }
                 else{
                     result=false;
                 }
             }
         }
     }
    System.out.println(result);

Updated One:

public class Test {

public static void main(String[] args) {

    int[] arrayA = { 7, 14, 21, 28 };
    int[] arrayB = { 1, 3, 5, 7, 14, 21, 28, 32, 7 };
    boolean output = Test.appearsConsecutive(arrayA,arrayB);
    System.out.println(output);
}

public static boolean appearsConsecutive(int[] arrayA, int[] arrayB) {

    boolean result = false;

    for (int i = 0; i < arrayB.length; i++) {

        if (arrayA[0] == arrayB[i]) {
            for (int j = 0; j < arrayA.length; j++) {
                if (arrayA[j] == arrayB[i + j]) {
                    result = true;
                    break;
                } else {
                    result = false;
                }
            }
        }
    }
    System.out.println(result);
    return result;

}

}

See above example.

edited Apr 3, 2017 at 8:52

answered Apr 3, 2017 at 5:57

Ashish Kumar

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9 Comments

Ashish Kumar Over a year ago

Kindly add break; after line result=true;

Cody Harrison Over a year ago

is it possible to add a separate method out of main that will return the boolean as well?

Ashish Kumar Over a year ago

Yes you can do that. Just write above code in a method and return result from there. If you need I can give code to you.

Cody Harrison Over a year ago

please provide an example, I would like the method to be named something like public static boolean appearsConsecutive or something like that, thank you very much

Ashish Kumar Over a year ago

Your Welcome..Always Happy to help :)

|

dev8080 · Accepted Answer · 2017-04-03 07:41:02Z

If anybody needs an algorithmic answer....(I've reversed arrayA and arrayB assignments).

public static void main (String[] args) throws java.lang.Exception
{
    // your code goes here
    int[] arrayB = {7,14,21,28};
    int[] arrayA = {1,3,5,7,14,21,28,32};

    boolean result = false;

    for(int A = 0; A < arrayA.length; A++)
    {
         if( arrayA[A] != arrayB[0]) continue;
         //else ... 
         for(int B = 0; B < arrayB.length; B++)
         {
                    if(arrayA[A] != arrayB[B] || A>=arrayA.length) 
                        break; 
                    if(B+1 == arrayB.length) 
                        {
                            result = true;
                            break;
                        }
                    A++;
         }
        if(result) 
            break;

      }
      System.out.println("Contains :"+ result);
 }

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