检查字符串是否包含特殊字符的 Java 程序
特殊字符是那些既不是字母也不是数字的字符。空白也不被认为是特殊字符。特殊字符的例子有:-！(感叹号)、、(逗号)、#(哈希)等。
方法:
- [使用字符类](https://www.geeksforgeeks.org/character-class-java/#:~:text=Syntax%20%3A%20char%20toLowerCase(char%20ch,of%20the%20specified%20char%20value.&text=toString(char%20ch)%20%3A%20It,we%20cannot%20pass%20ASCII%20value.)
- 使用正则表达式
方法 1: 使用字符类
方法如下:
- 遍历字符串的所有字符。
- 同时，我们将使用 java [字符类](https://www.geeksforgeeks.org/character-class-java/#:~:text=Syntax%20%3A%20char%20toLowerCase(char%20ch,of%20the%20specified%20char%20value.&text=toString(char%20ch)%20%3A%20It,we%20cannot%20pass%20ASCII%20value.)检查每个字符是字母、数字还是空白。
- 它被发现没有上述的特殊字符的标志。
- 并行地，我们将维护一个特殊字符计数的计数器。
- 最后，根据需要打印和显示所需的计数或特殊字符。
例
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check Whether String contains Special
// Characters Using Character Class
// Importing input output classes
import java.io.*;
// Main class
class GFG {
// Method 1
// Main driver method
public static void main(String[] args)
{
// Declaring and initializing count for
// special characters
int count = 0;
// Input custom string
String s
= "!#$GeeeksforGeeks.Computer.Science.Portal!!";
// Iterating through the string
// using standard length() method
for (int i = 0; i < s.length(); i++) {
// Checking the character for not being a
// letter,digit or space
if (!Character.isDigit(s.charAt(i))
&& !Character.isLetter(s.charAt(i))
&& !Character.isWhitespace(s.charAt(i))) {
// Incrementing the countr for spl
// characters by unity
count++;
}
}
// When there is no special character encounterd
if (count == 0)
// Display the print statement
System.out.println(
"No Special Characters found.");
else
// Special sharacter/s found then
// Display the print statement
System.out.println(
"String has Special Characters\n" + count + " "
+ "Special Characters found.");
}
}
Output
String has Special Characters
8 Special Characters found.
方法 2: 使用正则表达式
- 创建一个不匹配任何字母、数字或空白的正则表达式。
- 我们将根据正则表达式使用 Matcher 类作为我们的输入字符串。
- 现在，如果正则表达式中存在任何“字符匹配”，则字符串包含特殊字符，否则它不包含任何特殊字符。
- 打印结果。
Java 语言(一种计算机语言，尤用于创建网站)
// Java Program to Check Whether String contains Special
// Characters using Regex classes
// Importing regex classes from java.util package to
// match a specific patteren
import java.util.regex.Matcher;
import java.util.regex.Pattern;
// Main class
public class GFG {
// Main driver method
public static void main(String[] args)
{
// Declaring and initializing strings randomly
// with input characters
// Custom Input as String 1
String s1 = "GeeksForGeeks";
// Creating regex pattern by
// creating object of Pattern class
Pattern p = Pattern.compile(
"[^a-z0-9 ]", Pattern.CASE_INSENSITIVE);
// Creating matcher for above pattern on our string
Matcher m = p.matcher(s1);
// Now finding the matches for which
// let us set a boolean flag and
// imposing find() method
boolean res = m.find();
// Output will be based on boolean flag
// If special characters are found
if (res)
// Display this message on the console
System.out.println(
"String1 contains Special Characters");
// If we reach here means no special characters are
// found
else
// Display this message on the console
System.out.println(
"No Special Characters found in String 1");
// Custom Input as String 2
String s2 = "!!Geeks.For.Geeks##";
// Creating matcher for above pattern on our string
// by creating object of matcher class
Matcher m2 = p.matcher(s2);
// Finding the matches using find() method
boolean res2 = m2.find();
// If matches boolean returns true
if (res2)
// Then print and display thta special
// characters are found
System.out.println(
"String 2 contains Special Characters");
// If not
else
// Then Display the print statement below
System.out.println(
"No Special Characters found in String 2");
}
}
Output
No Special Characters found in String 1
String 2 contains Special Characters
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