前言
今天网上冲浪时，看到org.apache.commons.lang3.StringUtils工具类的isEmpty方法，就想到了isBlank这个方法，去做个笔记记录一下这两个系列的方法
一、isEmpty系列
1.StringUtils.isEmpty(),源码如下
/**
* <p>Checks if a CharSequence is empty ("") or null.</p>
*
* <pre>
* StringUtils.isEmpty(null) = true
* StringUtils.isEmpty("") = true
* StringUtils.isEmpty(" ") = false
* StringUtils.isEmpty("bob") = false
* StringUtils.isEmpty(" bob ") = false
* </pre>
*
* <p>NOTE: This method changed in Lang version 2.0.
* It no longer trims the CharSequence.
* That functionality is available in isBlank().</p>
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is empty or null
* @since 3.0 Changed signature from isEmpty(String) to isEmpty(CharSequence)
*/
public static boolean isEmpty(final CharSequence cs) {
return cs == null || cs.length() == 0;
}
可以看到 " " 空格是会绕过这种空判断,因为是一个空格,并不是严格的空值,会导致 isEmpty(" ")=false
2.StringUtils.isNotEmpty()方法，源码如下
/**
* <p>Checks if a CharSequence is not empty ("") and not null.</p>
*
* <pre>
* StringUtils.isNotEmpty(null) = false
* StringUtils.isNotEmpty("") = false
* StringUtils.isNotEmpty(" ") = true
* StringUtils.isNotEmpty("bob") = true
* StringUtils.isNotEmpty(" bob ") = true
* </pre>
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is not empty and not null
* @since 3.0 Changed signature from isNotEmpty(String) to isNotEmpty(CharSequence)
*/
public static boolean isNotEmpty(final CharSequence cs) {
return !isEmpty(cs);
}
判断字符串不为空 , 相当于!isEmpty(ss)方法
3. StringUtils.isAnyEmpty()方法源码如下
/**
* <p>Checks if any one of the CharSequences are empty ("") or null.</p>
*
* <pre>
* StringUtils.isAnyEmpty(null) = true
* StringUtils.isAnyEmpty(null, "foo") = true
* StringUtils.isAnyEmpty("", "bar") = true
* StringUtils.isAnyEmpty("bob", "") = true
* StringUtils.isAnyEmpty(" bob ", null) = true
* StringUtils.isAnyEmpty(" ", "bar") = false
* StringUtils.isAnyEmpty("foo", "bar") = false
* </pre>
*
* @param css the CharSequences to check, may be null or empty
* @return {@code true} if any of the CharSequences are empty or null
* @since 3.2
*/
public static boolean isAnyEmpty(final CharSequence... css) {
if (ArrayUtils.isEmpty(css)) {
return true;
}
for (final CharSequence cs : css){
if (isEmpty(cs)) {
return true;
}
}
return false;
}
是否有一个为空,只有一个为空,就为true.
4. StringUtils.isNoneEmpty()方法，源码如下
/**
* <p>Checks if none of the CharSequences are empty ("") or null.</p>
*
* <pre>
* StringUtils.isNoneEmpty(null) = false
* StringUtils.isNoneEmpty(null, "foo") = false
* StringUtils.isNoneEmpty("", "bar") = false
* StringUtils.isNoneEmpty("bob", "") = false
* StringUtils.isNoneEmpty(" bob ", null) = false
* StringUtils.isNoneEmpty(" ", "bar") = true
* StringUtils.isNoneEmpty("foo", "bar") = true
* </pre>
*
* @param css the CharSequences to check, may be null or empty
* @return {@code true} if none of the CharSequences are empty or null
* @since 3.2
*/
public static boolean isNoneEmpty(final CharSequence... css) {
return !isAnyEmpty(css);
}
必须所有的值都不为空才返回true，相当于!isAnyEmpty() ,
二、isBank系列
1. StringUtils.isBlank()方法，源码如下
/**
* <p>Checks if a CharSequence is whitespace, empty ("") or null.</p>
*
* <pre>
* StringUtils.isBlank(null) = true
* StringUtils.isBlank("") = true
* StringUtils.isBlank(" ") = true
* StringUtils.isBlank("bob") = false
* StringUtils.isBlank(" bob ") = false
* </pre>
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is null, empty or whitespace
* @since 2.0
* @since 3.0 Changed signature from isBlank(String) to isBlank(CharSequence)
*/
public static boolean isBlank(final CharSequence cs) {
int strLen;
if (cs == null || (strLen = cs.length()) == 0) {
return true;
}
for (int i = 0; i < strLen; i++) {
if (Character.isWhitespace(cs.charAt(i)) == false) {
return false;
}
}
return true;
}
是否为真空值(空格或者空值)，isBlank()判断了空格的存在
2. StringUtils.isNotBlank()，源码如下
/**
* <p>Checks if a CharSequence is not empty (""), not null and not whitespace only.</p>
*
* <pre>
* StringUtils.isNotBlank(null) = false
* StringUtils.isNotBlank("") = false
* StringUtils.isNotBlank(" ") = false
* StringUtils.isNotBlank("bob") = true
* StringUtils.isNotBlank(" bob ") = true
* </pre>
*
* @param cs the CharSequence to check, may be null
* @return {@code true} if the CharSequence is
* not empty and not null and not whitespace
* @since 2.0
* @since 3.0 Changed signature from isNotBlank(String) to isNotBlank(CharSequence)
*/
public static boolean isNotBlank(final CharSequence cs) {
return !isBlank(cs);
}
是否真的不为空,不是空格或者空值 ,相当于!isBlank();
3. StringUtils.isAnyBlank()，源码如下
/**
* <p>Checks if any one of the CharSequences are blank ("") or null and not whitespace only..</p>
*
* <pre>
* StringUtils.isAnyBlank(null) = true
* StringUtils.isAnyBlank(null, "foo") = true
* StringUtils.isAnyBlank(null, null) = true
* StringUtils.isAnyBlank("", "bar") = true
* StringUtils.isAnyBlank("bob", "") = true
* StringUtils.isAnyBlank(" bob ", null) = true
* StringUtils.isAnyBlank(" ", "bar") = true
* StringUtils.isAnyBlank("foo", "bar") = false
* </pre>
*
* @param css the CharSequences to check, may be null or empty
* @return {@code true} if any of the CharSequences are blank or null or whitespace only
* @since 3.2
*/
public static boolean isAnyBlank(final CharSequence... css) {
if (ArrayUtils.isEmpty(css)) {
return true;
}
for (final CharSequence cs : css){
if (isBlank(cs)) {
return true;
}
}
return false;
}
是否包含任何真空值(包含空格或空值)
4 StringUtils.isNoneBlank()，源码如下
/**
* <p>Checks if none of the CharSequences are blank ("") or null and whitespace only..</p>
*
* <pre>
* StringUtils.isNoneBlank(null) = false
* StringUtils.isNoneBlank(null, "foo") = false
* StringUtils.isNoneBlank(null, null) = false
* StringUtils.isNoneBlank("", "bar") = false
* StringUtils.isNoneBlank("bob", "") = false
* StringUtils.isNoneBlank(" bob ", null) = false
* StringUtils.isNoneBlank(" ", "bar") = false
* StringUtils.isNoneBlank("foo", "bar") = true
* </pre>
*
* @param css the CharSequences to check, may be null or empty
* @return {@code true} if none of the CharSequences are blank or null or whitespace only
* @since 3.2
*/
public static boolean isNoneBlank(final CharSequence... css) {
return !isAnyBlank(css);
}
是否全部都不包含空值或空格