Java Data Type How to - Check if a string is empty

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Question

We would like to know how to check if a string is empty.

Answer

To test whether a String object is empty. The length of an empty string is zero.

There are three ways to check for an empty string:

• isEmpty() method.
• equals() method.
• Get the length of the String and check if it is zero.

The following code shows how to use the three methods:

public class Main {
  public static void main(String[] args) {
    String str1 = "Hello";
    String str2 = "";
//w  w w.java  2s.c om
    // Using the isEmpty() method
    boolean empty1 = str1.isEmpty(); // Assigns false to empty1
    boolean empty2 = str2.isEmpty(); // Assigns true to empty1

    // Using the equals() method
    boolean empty3 = "".equals(str1); // Assigns false to empty3
    boolean empty4 = "".equals(str2); // Assigns true to empty4

    // Comparing length of the string with 0
    boolean empty5 = str1.length() == 0; // Assigns false to empty5
    boolean empty6 = str2.length() == 0; // Assigns true to empty6

  }
}

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