Interpretation of methods in Java

()The method comes from the Apache Commons Lang library, which is a very practical tool method to determine whether a string isnull, empty string or only whitespace characters.

The following is a detailed introduction to this method:

Introduce the library and dependencies

StringUtilsThe class belongs to the Apache Commons Lang library, if you want to use itisBlank()Method, you need to add the dependencies of the library to the project.

Take Maven as an example,Add the following dependencies:

<dependency>
    <groupId></groupId>
    <artifactId>commons-lang3</artifactId>
    <version>3.12.0</version>
</dependency>

Method signature

isBlank()The signature of the method is as follows:

public static boolean isBlank(CharSequence cs)

parameter：csIt's oneCharSequencetype parameter, which means it can receiveString、StringBuilder、StringBufferObjects of types.
Return value: Return onebooleanvalue of type, if the string isnull, empty string or only contains whitespace characters, returntrue; Otherwise returnfalse。

Method Function

isBlank()The method checks whether the passed string meets one of the following conditions:

1) The string isnull。
2) The string length is 0 (i.e., empty string).
3) The string only contains whitespace characters (such as spaces, tabs, line breaks, etc.).

Sample code

import .;

public class StringUtilsIsBlankExample {
    public static void main(String[] args) {
        // Test null string        String str1 = null;
        ((str1)); 

        // Test empty string        String str2 = "";
        ((str2)); 

        // Test strings containing only whitespace characters        String str3 = "   ";
        ((str3)); 

        // Test strings containing non-whitespace characters        String str4 = "hello";
        ((str4)); 
    }
}

Code explanation

When the incoming string isnullhour,isBlank()Method returntrue。
When the passed string is an empty string,isBlank()Method returntrue。
When the passed string contains only whitespace characters,isBlank()Method returntrue。
When the passed string contains non-whitespace characters,isBlank()Method returnfalse。

Comparison with other methods

isEmpty()method：

()Method only determines whether the string isnullOr an empty string, which does not check whether the string contains only whitespace characters.

For example,(" ")Will returnfalse,and(" ")Will returntrue。

StringClassicisEmpty()method：

StringClassicisEmpty()Methods can only be usedStringObject, and only determine whether the string length is 0, cannot be processednullvalue.

If truenullCallisEmpty()The method will be thrownNullPointerExceptionabnormal.

Summarize

The above is personal experience. I hope you can give you a reference and I hope you can support me more.