How to determine whether a java object is empty

When actually writing code, a null pointer exception java.lang.NullPointerException is often thrown because the object is empty.

Let’s take a look at the method of judging whether an object is empty in java: (Recommended: java video tutorial)

First, let’s take a look at the method of judging whether the tool StringUtils:

One is under the org.apache.commons.lang3 package;

The other is under the org.springframework.util package. There is a difference between these two StringUtils tool classes in determining whether an object is empty:

StringUtils.isEmpty(CharSequence cs); //org.apache.commons.lang3包下的StringUtils类，判断是否为空的方法参数是字符序列类，也就是String类型

StringUtils.isEmpty(Object str); //而org.springframework.util包下的参数是Object类，也就是不仅仅能判断String类型，还能判断其他类型，比如Long等类型。

From the above example, we can see that the second StringUtils class is more practical.

Let’s take a look at the source code of StringUtils.isEmpty(CharSequence cs) of org.apache.commons.lang3:

public static boolean isEmpty(final CharSequence cs) {
        return cs == null || cs.length() == 0;
}

The next step is StringUtils.isEmpty(Object str) of org.springframework.util Source code:

public static boolean isEmpty(Object str) {
        return (str == null || "".equals(str));
}

Basically determine whether the object is empty, StringUtils.isEmpty(Object str) can do this.

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