How to Check if a String Is Empty or Null in Java

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Hassan Saeed Feb 02, 2024
Java Java String
  1. Use str == null to Check if a String Is null in Java
  2. Use str.isEmpty() to Check if a String Is Empty in Java
How to Check if a String Is Empty or Null in Java

This tutorial discusses methods to check if a string is empty or null in Java.

Use str == null to Check if a String Is null in Java

The simplest way to check if a given string is null in Java is to compare it with null using str == null. The below example illustrates this:

public class MyClass {
  public static void main(String args[]) {
    String str1 = null;
    String str2 = "Some text";
    if (str1 == null)
      System.out.println("str1 is a null string");
    else
      System.out.println("str1 is not a null string");

    if (str2 == null)
      System.out.println("str2 is a null string");
    else
      System.out.println("str2 is not a null string");
  }
}

Output:

str1 is a null string
str2 is not a null string

Use str.isEmpty() to Check if a String Is Empty in Java

The simplest way to check if a given string is empty in Java is to use the built-in method of String class - isEmpty(). The below example illustrates this:

public class MyClass {
  public static void main(String args[]) {
    String str1 = "";
    String str2 = "Some text";
    if (str1.isEmpty())
      System.out.println("str1 is an empty string");
    else
      System.out.println("str1 is not an empty string");

    if (str2.isEmpty())
      System.out.println("str2 is an empty string");
    else
      System.out.println("str2 is not an empty string");
  }
}

Output:

str1 is an empty string
str2 is not an empty string

If we are interested in checking for both of the conditions at the same time, we can do so by using logical OR operator - ||. The below example illustrates this:

public class MyClass {
  public static void main(String args[]) {
    String str1 = "";
    if (str1.isEmpty() || str1 == null)
      System.out.println("This is an empty or null string");
    else
      System.out.println("This is neither empty nor null string");
  }
}

Output:

This is an empty or null string

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