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Java Program to Check if a String is Empty or Null
In this article, we will understand how to check if a string is empty or null. String is a datatype that contains one or more characters and is enclosed in double quotes(“ ”).
Below is a demonstration of the same −
Suppose our input is −
Input string: null
The desired output would be −
The string is a null string
Algorithm
Step 1 - START Step 2 - Declare a string namely input_string. Step 3 - Define the values. Step 4 - Using an if-loop, compute input_string == null. If true, the string is null, else the string is not null. Step 5 - Display the result Step 6 - Stop
Example 1
Here, we bind all the operations together under the ‘main’ function.
public class Demo {
public static void main(String[] args) {
String input_string = null;
System.out.println("The string is defined as: " +input_string);
if (input_string == null) {
System.out.println("\nThe string is a null string");
}
else if(input_string.isEmpty()){
System.out.println("\nThe string is an empty string");
} else {
System.out.println("\nThe string is neither empty nor null string");
}
}
}Output
The string is defined as: null The string is a null string
Example 2
Here, we encapsulate the operations into functions exhibiting object-oriented programming.
public class Demo {
static void isNullEmpty(String input_string) {
if (input_string == null) {
System.out.println("\nThe string is a null string");
}
else if(input_string.isEmpty()){
System.out.println("\nThe string is an empty string");
} else {
System.out.println("\nThe string is neither empty nor null string");
}
}
public static void main(String[] args) {
String input_string = null;
System.out.println("The string is defined as: " +input_string);
isNullEmpty(input_string);
}
}Output
The string is defined as: null The string is a null string
Updated on: 30-Mar-2022
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