Java method to determine whether it is empty
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- 2019-12-21 17:07:432640browse
Java method to determine whether it is empty:
1. Determine whether a string or object is empty
Judgment of StringUtils
StringUtils.isEmpty(CharSequence cs); //StringUtils class under the org.apache.commons.lang3 package, the method parameter to determine whether it is empty is the character sequence class, which is the String type
StringUtils.isEmpty(Object str); //The parameter under the org.springframework.util package is the Object class, which means it can not only determine the String type, but also other types, such as Long and other types.
StringUtils.isEmpty(CharSequence cs) source code of org.apache.commons.lang3:
public static boolean isEmpty(final CharSequence cs) {
return cs == null || cs.length() == 0;
}
StringUtils.isEmpty(Object str) source code of org.springframework.util ：
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.
2. Determine whether the array is empty
list.isEmpty(); //返回boolean类型。
3. Determine whether the collection is empty
CollectionUtils.isEmpty(null): true
CollectionUtils.isEmpty(new ArrayList()): true
CollectionUtils.isEmpty({a,b}): false
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