Java – Check if a String is empty or null

By mkyong | Updated: April 19, 2019

Viewed: 2,052 (+15 pv/w)

Tags: java

In Java, we can use (str != null && !str.isEmpty()) to make sure the String is not empty or null.

package com.mkyong;

public class StringNotEmpty {

    public static void main(String[] args) {

        System.out.println(notEmpty(""));      // false
        System.out.println(notEmpty(null));    // false
        System.out.println(notEmpty("hello")); // true
        System.out.println(notEmpty(" "));     // true, a space...

    }

    private static boolean notEmpty(String str) {
        if (str != null && !str.isEmpty()) {
            return true;
        } else {
            return false;
        }
    }

}

Output

false
false
true
true

If we want empty space like notEmpty(" ") to return false, update the code with .trim(),

	private static boolean notEmpty(String str) {
        if (str != null && !str.trim().isEmpty()) {
            return true;
        } else {
            return false;
        }
    }

References

• String.isEmpty() JavaDocs)