How to convert a String to an Int in Java?
Given a String str containing digits as characters, the task is to convert this given string to an integer in Java. In this article, we will learn how to convert a String to an Int in Java.
Examples:
Input: str = "1234"
Output: 1234
Input: str = "213s"
Output: 0
Since the String contains other than digits,
hence the integer value will be 0
Methods to convert a String to an Int in Java
There are certain methods to convert a String to an Int in Java as mentioned below:
1. Use Integer.parseInt() method
This is the most simple method to convert a String to an integer. The Integer.parseInt() function parses the string argument as a signed decimal integer.
Syntax:
public static int parseInt(String s)
throws NumberFormatException
Below is the implementation of the above approach:
Java
import java.io.*;
class GFG {
public static int convert(String str)
{
int val = 0 ;
System.out.println( "String = " + str);
try {
val = Integer.parseInt(str);
}
catch (NumberFormatException e) {
System.out.println( "Invalid String" );
}
return val;
}
public static void main(String[] args)
{
String str = "1234" ;
int val = convert(str);
System.out.println( "Integer value = " + val);
System.out.println();
str = "123s" ;
val = convert(str);
System.out.println( "Integer value = " + val);
}
}
|
Output
String = 1234
Integer value = 1234
String = 123s
Invalid String
Integer value = 0
2. Java valueOf() method
It is a method that converts String into Integer Object.
Below is the Implementation of the above method:
Java
import java.io.*;
import java.util.*;
class GFG {
public static void main(String[] args)
{
String str = "1234" ;
int val = Integer.valueOf(str);
System.out.println( "Integer value = " + val);
System.out.println();
}
}
|
Output
Integer value = 1234
Note: String literal, calling Integer.parseInt() or Integer.valueOf() methods throw NumberFormatException if you don’t have numbers.
3. Use the Ints::tryParse method of the Guava library
Another method to convert a String to an integer is to use the Ints::tryParse method of the Guava library. It is similar to the Integer.parseInt() method, but this method is more concise and powerful.
Syntax:
public static Integer tryParse(String s)
Below is the implementation of the above approach:
Java
import com.google.common.primitives.Ints;
import java.io.*;
import java.util.*;
class GFG {
public static int convert(String str)
{
int val = 0 ;
System.out.println( "String = " + str);
val = Optional.ofNullable(str)
.map(Ints::tryParse)
.orElse( 0 );
return val;
}
public static void main(String[] args)
{
String str = "1234" ;
int val = convert(str);
System.out.println( "Integer value = " + val);
System.out.println();
str = "123s" ;
val = convert(str);
System.out.println( "Integer value = " + val);
}
}
|
Output
String = 1234
Integer value = 1234
String = 123s
Integer value = 0
Last Updated :
22 Jun, 2023
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