如何打印字符，数字和特殊字符从给定的字符串在Java?

Question

给定字符串为str = "aQt4512m@!%n"输出:

character:aQtmn , Number:4512 special:@!%

下面是代码，我试过了，但是，它是一个唯一的打印字符

String str = "asDftQ32$34h";

char[] chArr = str.toCharArray();
Character myChar = '';

for(int i=0;i<chArr.length;i++) {
myChar = '';  
if(chArr[i]>=65 && chArr[i]<=122) {
myChar =chArr[i];   
}

String tr = myChar.toString();
String dr = tr.replaceAll("\W","");
System.out.print(dr);
}

Answer 1

您可以像示例中那样使用replaceAll()来实现:

public class Main {
public static void main( String[] arg ) {
String str = "aQt4512m@!%n";
String chars = str.replaceAll( "[\W\d]", "" );
System.out.println( chars );
String special = str.replaceAll( "\w", "" );
System.out.println( special );
String numbers = str.replaceAll( "\D", "" );
System.out.println( numbers );
}
}

查看更多关于正则表达式的信息:https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html

Answer 2

代码如下:

• 处理文本字符串
• 沿途检查每个字符c
• 如果c在a-z或a-z范围内，它将追加到名为"characters">
的StringBuilder中。
• 如果在0-9的范围内，则附加在"数字"后面;
• 如果它在其他一些特殊字符的范围内，它会追加到"special">
• 如果在这些范围之外，它将打印一条消息以及字符

private static void separateCharacters(String str) {
StringBuilder characters = new StringBuilder();
StringBuilder digits = new StringBuilder();
StringBuilder special = new StringBuilder();
for (int i = 0; i < str.length(); i++) {
char c = str.charAt(i);
if (Character.isAlphabetic(c)) {
characters.append(c);
} else if (Character.isDigit(c)) {
digits.append(c);
} else if ((c >= 33 && c <= 47) ||
(c >= 58 && c <= 64) ||
(c >= 91 && c <= 96) ||
(c >= 123 && c <= 126)) {
special.append(c);
} else {
System.out.println("skipping character: " + c);
}
}
System.out.println("characters : " + characters);
System.out.println("digits     : " + digits);
System.out.println("special    : " + special);
}

下面是输出"aQt4512m@!%n":

separateCharacters("aQt4512m@!%n");
characters : aQtmn
digits     : 4512
special    : @!%

再次,这次"aQt4512m@ ! % n(- =":

separateCharacters("azrRt07572m@!%n[-=");
characters : azrRtmn
digits     : 07572
special    : @!%[-=

我不喜欢"特别的"。处理，但这应该是一个足够的工作示例，以显示如何修改代码以包括/排除任何不同组的其他字符。或者，您可以选择遵循所有非字母、非数字字符都是"特殊"的逻辑，在这种情况下，您可以使用默认的"else";语句为special.append(c).

Answer 3

public void printString()
{
String input = "asDftQ32$34h";
List<Character> numbers = new ArrayList<>();
List<Character> letters = new ArrayList<>();
List<Character> specialChars = new ArrayList<>();
for (char current: input.toCharArray()) {
if(Character.isDigit(current))
{
numbers.add(current);
}
else if(Character.isAlphabetic(current))
{
letters.add(current);
}
else
specialChars.add(current);
}
System.out.println("All Letters In String :"+ letters);
System.out.println("All Numbers In String :"+ numbers);
System.out.println("All Special Characters In String :"+ specialChars);

}

使用字符API

Answer 4

由于您显然可以使用正则表达式，因此您可以使用字符类来简化此工作:

String str = "asDftQ32$34h";
System.out.println("character: " + str.replaceAll("\P{L}", ""));
System.out.println("number: " + str.replaceAll("\P{N}", ""));
System.out.println("special: " + str.replaceAll("\p{Alnum}", ""));