Approach 1: Traversing to each element of array and copy.
public static byte[] concat_approach1(byte[] arr1, byte[] arr2) {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
int arr1Length = arr1.length;
int arr2Length = arr2.length;
int totalElements = arr1Length + arr2Length;
byte[] arr3 = new byte[totalElements];
int counter = 0;
for (int i = 0; i arr3[counter++] = arr1[i];
}
for (int i = 0; i arr3[counter++] = arr2[i];
}
return arr3;
}
Approach 2: Using System.arraycopy
public static byte[] concat_approach2(byte[] arr1, byte[] arr2) {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
int arr1Length = arr1.length;
int arr2Length = arr2.length;
int totalElements = arr1Length + arr2Length;
byte[] arr3 = new byte[totalElements];
System.arraycopy(arr1, 0, arr3, 0, arr1Length);
System.arraycopy(arr2, 0, arr3, arr1Length, arr2Length);
return arr3;
}
Approach 3: Using ByteArrayOutputStream
public static byte[] concat_approach3(byte[] arr1, byte[] arr2) throws IOException {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
outputStream.write(arr1);
outputStream.write(arr2);
return outputStream.toByteArray();
}
Approach 4: Using ByteBuffer.
public static byte[] concat_approach4(byte[] arr1, byte[] arr2) throws IOException {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
int arr1Length = arr1.length;
int arr2Length = arr2.length;
ByteBuffer byteBuffer = ByteBuffer.allocate(arr1Length + arr2Length);
byteBuffer.put(arr1);
byteBuffer.put(arr2);
return byteBuffer.array();
}
Approach 5: Using String concatenation.
public static byte[] concat_approach5(byte[] arr1, byte[] arr2) {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
String s1 = new String(arr1);
String s2 = new String(arr2);
String result = s1 + s2;
return result.getBytes();
}
Find the below working application.
App.java
package com.sample.app;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
public class App {
public static void printArray(byte[] arr) {
if (arr == null || arr.length == 0) {
return;
}
for (byte ele : arr) {
System.out.print(ele + " ");
}
System.out.println();
}
public static byte[] concat_approach1(byte[] arr1, byte[] arr2) {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
int arr1Length = arr1.length;
int arr2Length = arr2.length;
int totalElements = arr1Length + arr2Length;
byte[] arr3 = new byte[totalElements];
int counter = 0;
for (int i = 0; i arr3[counter++] = arr1[i];
}
for (int i = 0; i arr3[counter++] = arr2[i];
}
return arr3;
}
public static byte[] concat_approach2(byte[] arr1, byte[] arr2) {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
int arr1Length = arr1.length;
int arr2Length = arr2.length;
int totalElements = arr1Length + arr2Length;
byte[] arr3 = new byte[totalElements];
System.arraycopy(arr1, 0, arr3, 0, arr1Length);
System.arraycopy(arr2, 0, arr3, arr1Length, arr2Length);
return arr3;
}
public static byte[] concat_approach3(byte[] arr1, byte[] arr2) throws IOException {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
outputStream.write(arr1);
outputStream.write(arr2);
return outputStream.toByteArray();
}
public static byte[] concat_approach4(byte[] arr1, byte[] arr2) throws IOException {
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
int arr1Length = arr1.length;
int arr2Length = arr2.length;
ByteBuffer byteBuffer = ByteBuffer.allocate(arr1Length + arr2Length);
byteBuffer.put(arr1);
byteBuffer.put(arr2);
return byteBuffer.array();
}
public static byte[] concat_approach5(byte[] arr1, byte[] arr2){
if (arr1 == null || arr1.length == 0) {
return arr2;
}
if (arr2 == null || arr2.length == 0) {
return arr1;
}
String s1 = new String(arr1);
String s2 = new String(arr2);
String result = s1 + s2;
return result.getBytes();
}
public static void main(String[] args) throws IOException {
byte[] arr1 = { 2, 3, 5, 7 };
byte[] arr2 = { 2, 4, 6, 8, 10 };
byte[] arr3 = concat_approach1(arr1, arr2);
byte[] arr4 = concat_approach2(arr1, arr2);
byte[] arr5 = concat_approach3(arr1, arr2);
byte[] arr6 = concat_approach4(arr1, arr2);
byte[] arr7 = concat_approach5(arr1, arr2);
printArray(arr3);
printArray(arr4);
printArray(arr5);
printArray(arr6);
printArray(arr7);
}
}
Output
2 3 5 7 2 4 6 8 10
2 3 5 7 2 4 6 8 10
2 3 5 7 2 4 6 8 10
2 3 5 7 2 4 6 8 10
2 3 5 7 2 4 6 8 10
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