Convert String to int using Java

In Java, we can use Integer.parseInt() method to convert a String to int.

Example 1. Using `Integer.parseInt()`

public static int parseInt(String s, int radix) throws NumberFormatException Parses the string argument as a signed decimal integer.
The Example below can be used to convert a String “1000” to an primitive integer.

/*
 java string to int
*/

public class StringToInt {

    public static void main(String[] args) {

        String number = "1000";
        int value = Integer.parseInt(number);
        System.out.println(value);

    }
}

/*
Output:
1000

*/

Integer.parseInt() throws NumberFormatException

/*
 java string to int
*/

public class StringToInt {

    public static void main(String[] args) {

        String number = "1000abcdef";
        int value = Integer.parseInt(number);
        System.out.println(value);

    }
}

/*
Output:
Exception in thread "main" java.lang.NumberFormatException: For input string: "1000abcdef"
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:65)
	at java.lang.Integer.parseInt(Integer.java:580)
	at java.lang.Integer.parseInt(Integer.java:615)
	at app.main(app.java:10)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:483)
	at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

*/

Other examples of using Integer.parseInt()

Examples:

 parseInt("0", 10) returns 0
 parseInt("473", 10) returns 473
 parseInt("+42", 10) returns 42
 parseInt("-0", 10) returns 0
 parseInt("-FF", 16) returns -255
 parseInt("1100110", 2) returns 102
 parseInt("2147483647", 10) returns 2147483647
 parseInt("-2147483648", 10) returns -2147483648
 parseInt("2147483648", 10) throws a NumberFormatException
 parseInt("99", 8) throws a NumberFormatException
 parseInt("Kona", 10) throws a NumberFormatException
 parseInt("Kona", 27) returns 411787

Example 2. Java convert string to int Using `Integer.valueOf()`

Integer.valueOf() Returns an Integer object holding the value extracted from the specified String when parsed with the radix given by the second argument.

/*
 java string to int
*/

public class StringToInt {

    public static void main(String[] args) {

        String number = "1000";
        Integer value = Integer.valueOf(number);
        System.out.println(value);

    }
}

/*
Output:
1000

*/

Sources: