Here you will learn how to copy one array to another in Java.
There are mainly four different ways to copy all elements of one array into another array in Java.
1. Manually
2. Arrays.copyOf()
3. System.arraycopy()
4. Object.clone()
Lets discuss each of them in brief.
How to Copy One Array to Another in Java
1. Manually
In this method we manually copy elements one by one. It is not an efficient way. Below example shows how to do this.
Example:
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package com; public class CopyArrayExample { public static void main(String args[]){ int a[]={10,20,30,40,50}; int b[]=new int[a.length]; //copying one array to another for(int i=0;i<a.length;++i){ b[i]=a[i]; } //printing array for(int i=0;i<b.length;++i){ System.out.print(b[i]+" "); } } } |
2. Arrays.copyOf()
We can directly copy one array to another by using Arrays.copyOf() method. It has following syntax.
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public static int[] copyOf(int[] original,int newLength) |
Example:
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package com; import java.util.Arrays; public class CopyArrayExample { public static void main(String args[]){ int a[]={10,20,30,40,50}; int b[]=new int[a.length]; //copying one array to another b=Arrays.copyOf(a,a.length); //printing array for(int i=0;i<b.length;++i){ System.out.print(b[i]+" "); } } } |
3. System.arraycopy()
It is another method that directly copies one array to another. It has following syntax.
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public static void arraycopy(Object src, int srcPos, Object dest, int destPos, int length) |
Example:
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package com; public class CopyArrayExample { public static void main(String args[]){ int a[]={10,20,30,40,50}; int b[]=new int[a.length]; //copying one array to another System.arraycopy(a,0,b,0,a.length); //printing array for(int i=0;i<b.length;++i){ System.out.print(b[i]+" "); } } } |
4. Object.clone()
We can also use clone() method of Object class to make a copy of an array.
Example:
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package com; public class CopyArrayExample { public static void main(String args[]){ int a[]={10,20,30,40,50}; int b[]=new int[a.length]; //copying one array to another b=a.clone(); //printing array for(int i=0;i<b.length;++i){ System.out.print(b[i]+" "); } } } |
Comment below if you have any doubt related to above tutorial or you know about any other way to copy one array to another in Java.
Nice post. Can you please benchmark them and post the results. I think most people will click this article to see these results.
For the copyOf function of the Array class, I see it returns an array of integers. If that’s the case why do you still instantiate the destination array (which in our case is array b)?
Thank you very much sir … it is so knowledgeable. i hope you will send me programs like this again
// Improvisation for example Arrays.copyOf(T[],int)
package com;
import java.util.Arrays;
public class CopyArrayExample {
public static void main(String args[]){
int a[]={10,20,30,40,50};
/*int b[]=new int[a.length]; no need to create another array object since
Arrays.copyOf () method itself returning array object */
//copying one array to another
int[] b=Arrays.copyOf(a,a.length);// just create a reference variable of type int [] and store the object returned by the static factory method of Arrays class i.e copyOf(T[],int) method
//printing array
for(int i=0;i<b.length;++i){
System.out.print(b[i]+" ");
}
}
}