Converting a String array into an int Array in java

Question

I am new to java programming  My question is this I have a String array but when I am trying to convert it to an int array I keep getting  java lang NumberFormatException   My code is   private void processLine String   strings        Integer   intarray new Integer strings length       int i 0      for String str strings           intarray i  Integer parseInt str    Exception in this line         i              Any help would be great thanks

User · Answer

import java io BufferedReader  import java io IOException  import java io InputStreamReader   public class array test    public static void main String args    throws IOException   BufferedReader br   new BufferedReader new InputStreamReader System in    String line   br readLine     String   s array   line split            Splitting the array of number  separated by space into string array     Integer    a   new Integer s array length      Creating the int array of size equals to string array        for int i  0  i lt a length i                  a i   Integer parseInt s array i      Parsing from string to int          System out println a i                  your integer array is ready to use

User · Answer

This is because your string does not strictly contain the integers in string format  It has alphanumeric chars in it

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Another short way   int   myIntArray   Arrays stream myStringArray  mapToInt Integer  parseInt  toArray

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To help debug  and make your code better  do this   private void processLine String   strings        Integer   intarray new Integer strings length       int i 0      for String str strings           try               intarray i  Integer parseInt str               i              catch  NumberFormatException e                throw new IllegalArgumentException  Not a number      str     at index     i  e                       Also  from a code neatness point  you could reduce the lines by doing this   for  String str   strings      intarray i      Integer parseInt str

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To get rid of additional whitespace  you could change the code like this   intarray i  Integer parseInt str trim        No more Exception in this line

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Suppose  for example  that we have a arrays of strings   String   strings     1    2    3      With Lambda Expressions  1   2   since Java 8   you can do the next     int   array   Arrays asList strings  stream   mapToInt Integer  parseInt  toArray        This is another way   int   array   Arrays stream strings  mapToInt Integer  parseInt  toArray                                  Notes   1  Lambda Expressions in The Java Tutorials    2  Java SE 8  Lambda Quick Start

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Since you are trying to get an Integer   array you could use   Integer   intarray   Stream of strings  mapToInt Integer  parseInt  boxed   toArray Integer    new     Your code   private void processLine String   strings        Integer   intarray   Stream of strings  mapToInt Integer  parseInt  boxed   toArray Integer    new       Note  that this only works for Java 8 and higher

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public static int   strArrayToIntArray String   a       int   b   new int a length       for  int i   0  i  lt  a length  i              b i    Integer parseInt a i               return b      This is a simple function  that should help you   You can use him like this   int   arr   strArrayToIntArray   YOUR STR ARRAY

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private void processLine String   strings        Integer   intarray new Integer strings length       for int i 0 i lt strings length i              intarray i  Integer parseInt strings i              for Integer temp intarray            System out println  convert int array from String  temp

[java] Converting a String array into an int Array in java

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