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!!!
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
Integer[] array = Arrays.stream(strings).mapToInt(Integer::parseInt).boxed().toArray(Integer[]::new);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
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);
Another short way:
int[] myIntArray = Arrays.stream(myStringArray).mapToInt(Integer::parseInt).toArray();
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.
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<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.
}
}
public static int[] strArrayToIntArray(String[] a){
int[] b = new int[a.length];
for (int i = 0; i < 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*/);
private void processLine(String[] strings) {
Integer[] intarray=new Integer[strings.length];
for(int i=0;i<strings.length;i++) {
intarray[i]=Integer.parseInt(strings[i]);
}
for(Integer temp:intarray) {
System.out.println("convert int array from String"+temp);
}
}
int[]notInteger[].