CODEWITHSUNDEEP
javaarrays
sup
sup

Reputation: 101

adding elements of one array to another at a particular place in java

I have two arrays:

byte[] array1=new byte[]{0x01,0x05};
byte[] array2=new byte[]{0x03,0x04,0x02};

I want to add array2 in between array1[0] and array1[1].I do not want to delete any values from array1 after adding array2.Whatever may be the values in array2,it should be added to array1 as it is.I am not expecting the sorted order.

How can I do it?

Upvotes: 0

Views: 145

Answers (6)

Sergej Werfel
Sergej Werfel

Reputation: 1365

The following code returns a new array that containing the data from insertIn to index position, then all data from toInsert and then the rest of insertIn (This code is not fully tested, please implement a unit test for that method ;-) )

import static java.lang.System.arraycopy;
import java.util.Arrays;

public class MyCopy {

    public static void main(String[] args) {
        byte[] array1 = new byte[] {0x01, 0x05 };
        byte[] array2 = new byte[] {0x03, 0x04, 0x02 };

        // add array 2 in array 1 at index 1
        byte[] inserted = insertIn(array1, array2, 1);
        System.out.println(Arrays.toString(inserted));
    }

    public static byte[] insertIn(byte[] insertIn, byte[] toInsert, int position) {
        assert position > 0 && position <= insertIn.length;

        byte[] result = new byte[insertIn.length + toInsert.length];
        // copy start of insertIn
        arraycopy(insertIn, 0, result, 0, position);
        // copy toInsert
        arraycopy(toInsert, 0, result, position, toInsert.length);
        // copy rest of insertIn
        int restIndexInResult = position + toInsert.length;
        int restLength = toInsert.length - position - 1;
        arraycopy(insertIn, position, result, restIndexInResult , restLength);
        return result;
    }
}

Result: [1, 3, 4, 2, 5]

Upvotes: 2

Harish Naidu
Harish Naidu

Reputation: 35

here is the method using systemarraycopy which accepts the two arrays and positon where the second array you want insert in the first array 

public static byte[] append(byte[] a, byte[] b,int position) {
byte[] c= new byte[a.length+b.length];
System.arraycopy(a, 0, c, 0, position);
System.arraycopy(b, 0, c, position, b.length);
System.arraycopy(a, position , c, position + b.length , a.length - position);
return c; }

Upvotes: 0

Sudhir
Sudhir

Reputation: 11

A simple solution can be the following:

    byte[] array1=new byte[]{0x01,0x05};
    byte[] array2=new byte[]{0x02,0x03,0x04};

    byte[] newArray = new byte[array1.length+array2.length];
    newArray[0]=array1[0];
    for(int i=1; i<newArray.length; i++){
        if(i<=array2.length){
            newArray[i]=array2[i-1];
        }else{
            newArray[i]=array1[i-3];
        }           
    }

Upvotes: 1

dly
dly

Reputation: 1088

You need a third array to accomplish this.

    byte[] array1=new byte[]{0x01,0x05};
    byte[] array2=new byte[]{0x03,0x04,0x02};
    byte[] targetArray = new byte[array1.length + array2.length];

    System.arraycopy(array1, 0, targetArray, 0, array1.length);
    System.arraycopy(array2, 0, targetArray, array1.length, array2.length);

    for (byte b : targetArray) {
        System.out.println(b);
    }

result:

1
5
3
4
2

Alternative to put array2 in between array1s values

    byte[] array1=new byte[]{0x01,0x05};
    byte[] array2=new byte[]{0x03,0x04,0x02};
    byte[] targetArray = new byte[array1.length + array2.length];
    int cap = array1.length / 2;

    System.arraycopy(array1, 0, targetArray, 0, cap);
    System.arraycopy(array2, 0, targetArray, cap, array2.length);
    System.arraycopy(array1, cap, targetArray, array2.length + cap, array1.length - cap);

    for (byte b : targetArray) {
        System.out.println(b);
    }

Result: 

1
3
4
2
5

Upvotes: 1

Nitesh Virani
Nitesh Virani

Reputation: 1712

You can use below code to combile both array, you have to create third array which will hold both arrays data:

    byte[] array1=new byte[]{0x01,0x05};
    byte[] array2=new byte[]{0x02,0x03,0x04};

    int array1Len = array1.length;
    int array2Len = array2.length;
    byte[] array3 = new byte[array1Len+array2Len];

    System.arraycopy(array1, 0, array3, 0, array1Len);
    System.arraycopy(array2, 0, array3, array1Len, array2Len);

Upvotes: 0

npinti
npinti

Reputation: 52185

You will need to create a new array which is of size array1.length + array2.length and then using something like System.arrayCopy to throw in your current arrays in the order you need them to be,

Upvotes: 2

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