Converting ArrayList to Array in java
JavaArraysArraylistJava Problem Overview
I have an ArrayList with values like "abcd#xyz" and "mnop#qrs". I want to convert it into an Array and then split it with # as delimiter and have abcd,mnop in an array and xyz,qrs in another array. I tried the following code:
String dsf[] = new String[al.size()];
for(int i =0;i<al.size();i++){
dsf[i] = al.get(i);
}
But it failed saying "Ljava.lang.String;@57ba57ba"
Java Solutions
Solution 1 - Java
You don't need to reinvent the wheel, here's the toArray()
method:
String []dsf = new String[al.size()];
al.toArray(dsf);
Solution 2 - Java
List<String> list=new ArrayList<String>();
list.add("sravan");
list.add("vasu");
list.add("raki");
String names[]=list.toArray(new String[list.size()])
Solution 3 - Java
List<String> list=new ArrayList<String>();
list.add("sravan");
list.add("vasu");
list.add("raki");
String names[]=list.toArray(new String[0]);
if you see the last line (new String[0]), you don't have to give the size, there are time when we don't know the length of the list, so to start with giving it as 0 , the constructed array will resize.
Solution 4 - Java
import java.util.*;
public class arrayList {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
ArrayList<String > x=new ArrayList<>();
//inserting element
x.add(sc.next());
x.add(sc.next());
x.add(sc.next());
x.add(sc.next());
x.add(sc.next());
//to show element
System.out.println(x);
//converting arraylist to stringarray
String[]a=x.toArray(new String[x.size()]);
for(String s:a)
System.out.print(s+" ");
}
}
Solution 5 - Java
String[] values = new String[arrayList.size()];
for (int i = 0; i < arrayList.size(); i++) {
values[i] = arrayList.get(i).type;
}
Solution 6 - Java
What you did with the iteration is not wrong from what I can make of it based on the question. It gives you a valid array of String objects. Like mentioned in another answer it is however easier to use the toArray() method available for the ArrayList object => http://docs.oracle.com/javase/1.5.0/docs/api/java/util/ArrayList.html#toArray%28%29
Just a side note. If you would iterate your dsf array properly and print each element on its own you would get valid output. Like this:
for(String str : dsf){
System.out.println(str);
}
What you probably tried to do was print the complete Array object at once since that would give an object memory address like you got in your question. If you see that kind of output you need to provide a toString() method for the object you're printing.
Solution 7 - Java
package com.v4common.shared.beans.audittrail;
import java.util.ArrayList;
import java.util.List;
public class test1 {
public static void main(String arg[]){
List<String> list = new ArrayList<String>();
list.add("abcd#xyz");
list.add("mnop#qrs");
Object[] s = list.toArray();
String[] s1= new String[list.size()];
String[] s2= new String[list.size()];
for(int i=0;i<s.length;i++){
if(s[i] instanceof String){
String temp = (String)s[i];
if(temp.contains("#")){
String[] tempString = temp.split("#");
for(int j=0;j<tempString.length;j++) {
s1[i] = tempString[0];
s2[i] = tempString[1];
}
}
}
}
System.out.println(s1.length);
System.out.println(s2.length);
System.out.println(s1[0]);
System.out.println(s1[1]);
}
}
Solution 8 - Java
Here is the solution for you given scenario -
List<String>ls = new ArrayList<String>();
ls.add("dfsa#FSDfsd");
ls.add("dfsdaor#ooiui");
String[] firstArray = new String[ls.size()];
firstArray =ls.toArray(firstArray);
String[] secondArray = new String[ls.size()];
for(int i=0;i<ls.size();i++){
secondArray[i]=firstArray[i].split("#")[0];
firstArray[i]=firstArray[i].split("#")[1];
}
Solution 9 - Java
This is the right answer you want and this solution i have run my self on netbeans
ArrayList a=new ArrayList();
a.add(1);
a.add(3);
a.add(4);
a.add(5);
a.add(8);
a.add(12);
int b[]= new int [6];
Integer m[] = new Integer[a.size()];//***Very important conversion to array*****
m=(Integer[]) a.toArray(m);
for(int i=0;i<a.size();i++)
{
b[i]=m[i];
System.out.println(b[i]);
}
System.out.println(a.size());
Solution 10 - Java
This can be done using stream:
List<String> stringList = Arrays.asList("abc#bcd", "mno#pqr");
List<String[]> objects = stringList.stream()
.map(s -> s.split("#"))
.collect(Collectors.toList());
The return value would be arrays of split string. This avoids converting the arraylist to an array and performing the operation.
Solution 11 - Java
We can convert ararylist to array using 3 mrthod
-
public Object[] toArray() - it will return array of object
Object[] array = list.toArray();
-
public
T[] toArray(T[] a) - In this way we will create array and toArray Take it as argument then return it String[] arr = new String[list.size()]; arr = list.toArray(arr);
-
Public get() method;
Iterate ararylist and one by one add element in array.
For more details for these method Visit Java Vogue
Solution 12 - Java
public
String[] arr = new String[list.size()];
arr = list.toArray(arr);