Java Character isDigit()用法及代碼示例

java.lang.Character.isDigit(char ch)是java中的一種內置方法，該方法確定指定字符是否為數字。字符必須滿足幾個條件才能被接受為數字。也就是說，如果Character.getType(ch)提供的字符的常規類別類型為DECIMAL_DIGIT_NUMBER，則該字符為數字。某些包含數字的Unicode字符範圍：

From ‘\u0030’ to ‘\u0039’:ISO-LATIN-1 digits (‘0’ through ‘9’)
From ‘\u0660’ to ‘\u0669’:Arabic-Indic digits
From ‘\u06F0’ to ‘\u06F9’:Extended Arabic-Indic digits
From ‘\u0966’ to ‘\u096F’:Devanagari digits
From ‘\uFF10’ to ‘\uFF19’:Fullwidth digits

除上述範圍外，許多其他字符範圍也包含數字。

用法:

public static boolean isDigit(char ch)

參數：此方法接受字符參數ch作為參數，將對其進行測試。

返回值：此方法返回一個布爾值。如果ch是數字，則返回True，否則返回False。

注意：此方法不能處理補充字符。要支持所有Unicode字符(包括補碼)，請使用isDigit(int)方法。

以下示例程序旨在說明上述方法：
程序1:

// Java program to illustrate the 
// Character.isDigit() method 
  
import java.util.*; 
import java.lang.*; 
  
public class GFG { 
  
    public static void main(String[] args) 
    { 
  
        // two characters 
        char c1 = 'A', c2 = '4'; 
  
        // Function to check if the character 
        // is digit or not 
        System.out.println( 
            c1 + " is a digit -> "
            + Character.isDigit(c1)); 
        System.out.println( 
            c2 + " is a digit -> "
            + Character.isDigit(c2)); 
    } 
}

輸出：

A is a digit -> false
4 is a digit -> true

程序2:

// Java program to illustrate the 
// Character.isDigit() method 
  
import java.util.*; 
import java.lang.*; 
  
public class GFG { 
  
    public static int search_digit(String s) 
    { 
  
        // Function to check if is digit 
        // is found or not 
        for (int i = 0; i < s.length(); i++) { 
            if (Character.isDigit( 
                    s.charAt(i)) 
                == true) { 
                // return position of digit 
                return i + 1; 
            } 
        } 
        // return 0 if digit not present 
        return 0; 
    } 
  
    public static void main(String[] args) 
    { 
  
        // Array of strings 
        String[] arr = { "ABC4DEF", "QWERTY" }; 
  
        // To store the position of digit 
        int index = 0; 
  
        // Traverse the array arr[] to find digit 
        // within it's elements 
        for (String x:arr) { 
            index = search_digit(x); 
            if (index != 0) { 
                System.out.println( 
                    "Digit found at:"
                    + (index) 
                    + "th position."); 
            } 
            else { 
                System.out.println( 
                    "Digit not present."); 
            } 
        } 
    } 
}

輸出：

Digit found at:4th position.
Digit not present.

java.lang.Character.isDigit(int codePoint)是java中的一個內置方法，它確定整數類型的指定Unicode代碼點字符是否為數字。字符必須滿足幾個條件才能被接受為數字。也就是說，如果由getType(codepoint)提供的字符的常規類別類型為DECIMAL_DIGIT_NUMBER，則該字符為數字。某些包含數字的Unicode字符範圍：

From ‘\u0030’ to ‘\u0039’:ISO-LATIN-1 digits (‘0’ through ‘9’)
From ‘\u0660’ to ‘\u0669’:Arabic-Indic digits
From ‘\u06F0’ to ‘\u06F9’:Extended Arabic-Indic digits
From ‘\u0966’ to ‘\u096F’:Devanagari digits
From ‘\uFF10’ to ‘\uFF19’:Fullwidth digits

除上述範圍外，許多其他字符範圍也包含數字。

用法:

public static boolean isDigit(int codePoint)

參數：此方法接受整數類型的Unicode字符參數codePoint作為參數，將對其進行測試。

返回值：此方法返回一個布爾值。如果指定字符為數字，則返回True，否則返回False。

以下示例程序旨在說明上述方法：
程序1:

// This program demonstrates the use of 
// isDigit(int codePoint) method of Character class. 
import java.util.*; 
  
public class GFG { 
    public static void main(String[] args) 
    { 
        // create codePoints 
        int cp1 = 57; 
        int cp2 = 84; 
  
        // Check whether the codePoints 
        // are digit or not. 
        System.out.println( 
            "The codePoint cp1 is a digit -> "
            + Character.isDigit(cp1)); 
        System.out.println( 
            "The codePoint cp2 is a digit -> "
            + Character.isDigit(cp2)); 
    } 
}

輸出：

The codePoint cp1 is a digit -> true
The codePoint cp2 is a digit -> false

程序2:

// This program demonstrates the use of 
// isDigit(int codePoint) method of 
// Character class. 
import java.util.*; 
  
public class Main { 
    public static void main(String[] args) 
    { 
        // create codePoints 
        int cp1 = 0x50; 
        int cp2 = 0x06f8; 
  
        // Check whether the codePoints 
        // are digit or not. 
        System.out.println( 
            "The codePoint cp1 is a digit -> "
            + Character.isDigit(cp1)); 
        System.out.println( 
            "The codePoint cp2 is a digit -> "
            + Character.isDigit(cp2)); 
    } 
}

輸出：

The codePoint cp1 is a digit -> false
The codePoint cp2 is a digit -> true

參考：https://docs.oracle.com/javase/8/docs/api/java/lang/Character.html#isDigit-char-

相關用法

注：本文由純淨天空篩選整理自ashmitraj089大神的英文原創作品 Character isDigit() method in Java with examples。非經特殊聲明，原始代碼版權歸原作者所有，本譯文未經允許或授權，請勿轉載或複製。