转换列表<String[]>到 int[]

Question

如果可以将字符串(ArrayList<String[]>)转换为整数数组(int[]) ，是否可以将字符串数组数组列表(ArrayList<String[]>)转换为整数数组(int[]) ?

Answer 1

In Java 8:

list.stream().mapToInt(Integer::parseInt).toArray();

---

edit

Since the question was edited with List<String[]> instead of List<String> , a solution would be:

list.stream().flatMap(Arrays::stream).mapToInt(Integer::parseInt).toArray();

Answer 2

i have modified the code according to your edited answer,do reply if this is what you want.

 import java.util.*;
    import java.lang.*;
    import java.io.*;


    class Ideone
    {
        public static void main (String[] args) throws java.lang.Exception
        {
            ArrayList<String[]> strArrayList= new ArrayList<String[]>();
            String[] str1={"16","1421","1577"};

            String[] str2={"15","1451","1461","6556"};

            String[] str3={"157","8751","1136","556","879"};

            strArrayList.add(str1);
            strArrayList.add(str2);
            strArrayList.add(str3);


            int sizeOfArr=0;
            int i=0;

            for (String[] s : strArrayList)
            {

                sizeOfArr+=s.length;
            }

            int[] ArrayRes = new int[sizeOfArr];


            for (String[] s : strArrayList)
            {
                if(s.length>0){
                    for (String s1 : s){
                        ArrayRes[i] = Integer.parseInt(s1);
                        System.out.println(ArrayRes[i]);
                        i++;
                    }
                }
            }

        }
    }

Answer 3

run the below code,i hope it meets you requirement.

import java.util.*;
import java.lang.*;
import java.io.*;


class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        ArrayList<String> strArrayList= new ArrayList<String>();
            strArrayList.add("1");
            strArrayList.add("11");
            strArrayList.add("111");
            strArrayList.add("12343");
            strArrayList.add("18475");
        int[] ArrayRes = new int[strArrayList.size()];

        int i = 0;
        int x = 0;
        for (String s : strArrayList)
        {

            ArrayRes[i] = Integer.parseInt(s);
            System.out.println(ArrayRes[i]);
            i++;
        }

    }
}

Output:

1
11
111
12343
18475

Answer 4

Further to my comment, you'll need to work out how to map from 2D to 1D array.

Here's a suggestion which results in Integer[] rather than int[] but you might not worry about that:

public static void main(String[] args) {

    ArrayList<String[]> arrList = new ArrayList<String[]>();

    //fill it
    arrList.add(new String[] {"11","12","13","14","15"});
    arrList.add(new String[] {"21","22","23","24","25"});
    arrList.add(new String[] {"31","32","33","34","35"});
    arrList.add(new String[] {"41","42","43","44","45"});
    arrList.add(new String[] {"41","52","53","54","55"});

    //convert it
    ArrayList<Integer> ints = new ArrayList<Integer>();
    for (String[] array : arrList) {
        for (String str : array) {
            ints.add(Integer.parseInt(str));
        }
    }

    Integer[] result = ints.toArray(new Integer[] {});

    for (int i : result)
        System.out.println(i);
}

Answer 5

It is possible if all the Strings can be parsed to integers correctly.

Iterate over the list and in the list over the array. Parse the Strings to Integers (eg with Integer.parseInt(someString); ) and store the integervalues in the integer array.

Of course you'll have to find the total number of values in the list to initialize the array.