We can most of the time convert JAVA String to Int or Integer. So in this tutorial will see all the methods and examples to convert JAVA String to Int, JAVA String to int array or double or in any kind of value.
Obliviously we are looking to convert a String of Integer into Integer or Array of Integer in any scenario. So, Let dive into it that how can we convert JAVA String to Int with Examples
Initialization of String
We can initialize a String Object in JAVA as mentioned below. Note: All the methods are related to JAVA 8. So Lets Initialize String Object with the value 123456.
String numString = new String("123456");
Now we would like to convert the above string of numbers into integers which are required maybe for some calculation in your program ahead. So let look into a complete example.
Static Method parseInt() of Integer Class
To convert JAVA string to int we have a static method defined in the Integer class named parseInt. This is an inbuilt function to convert a stream of string into an integer.
Example
public class Solution
{
public static void main(String[] args) {
String numString = new String("123457");
//This will print the String number as 123457
System.out.println(numString);
//Now lets create a integer variable num and add 20 to it
// to make sure that we are able to do airthmetic operations
int num = Integer.parseInt(numString);
num = num + 20;
//This will print the String number as 123477
System.out.println(num);
}
}
Note that if you do not have numbers in the String variable then you will get NumberFormatException Error. Hence to handle it make sure you have taken care that String only contains numbers.
Static Method valueOf() of Integer Class
valueOf is another method defined in Integer Class to convert JAVA String to int. So let’s understand the use of valueOf by Simple Example Code. As it will provide a clearer picture.
public class Solution
{
public static void main(String[] args) {
String numString = new String("123457");
//This will print the String number as 123457
System.out.println(numString);
//Now lets create a integer variable num and add 20 to it
// to make sure that we are able to do airthmetic operations
int num = Integer.valueOf(numString);
num = num + 20;
//This will print the String number as 123477
System.out.println(num);
}
}
JAVA String to Int Array
Now another problem which may face is to get a spaced separated String of number to be converted to Integer Array. How can we convert JAVA String to Int Array? To find it let’s see example code for better understanding.
public class Solution
{
public static void main(String[] args) {
String numString = new String("1 2 3 4 5 6 7");
//Seperate the number by splitting using spaces
String[] numStringArray = numString.split(" ");
//Now numStringArray = {"1","2","3","4","5","6","7"}
//To get these number converted to integer array
int[] intArray = new int[numStringArray.length];
//Now Loop Through all the elements of numStringArray and Use
//parseInt() method to convert and store them in intArray
int i = 0;
for(String currNum:numStringArray){
intArray[i++] = Integer.parseInt(currNum);
}
//Print all the numbers store in intArray
for(int num:intArray)
System.out.println(num);
}
}
So as seen above we first used the method split() to get the String separated with numbers and then we stored it in a string array. After that, we ran through each string stored in a string array and converted it into an integer and then we stored that integer into an array.
The For Loop used in the above code corresponds to JAVA 8 standards and we can also use a typical normal loop through method for easier understanding if you are a newbie.
So this way we are able to do JAVA String to int or double conversion. Also, the same method can be followed for JAVA String to double conversion.
So that’s it for today. If you have any suggestions or query feel free to comment. Also, like my Facebook page and follow me on Twitter.
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