Java 中的 Character isDigit()方法，带示例
原文:https://www . geesforgeks . org/character-is digit-method-in-Java-with-examples/
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The java.lang.Character.isDigit(char ch) is an inbuilt method in java which determines whether a specified character is a digit or not. There are few conditions that a character must accomplish to be accepted as a digit. That is if the general category type of a character, provided by Character.getType(ch), is DECIMAL_DIGIT_NUMBER, then the character is a digit. Some Unicode character ranges that contain digits:
从' \u0030 '到' \u0039' : ISO-LATIN-1 数字(' 0 '到' 9') 从' \u0660 '到' \u0669 ':阿拉伯-印度数字 从' \u06F0 '到' \u06F9 ':扩展阿拉伯-印度数字 从' \u0966 '到' \u096F ':梵文数字 从' \uFF10 '到' \uFF19 ':全幅
除了上述范围，许多其他字符范围也包含数字。
语法:
```java public static boolean isDigit(char ch)
```
参数:该方法接受字符参数 ch 作为自变量，待测试。
返回值:这个方法返回一个布尔值。如果 ch 是数字，则返回 True ，否则返回 False。
注意:此方法无法处理补充字符。若要支持所有 Unicode 字符，包括补充字符，请使用 isDigit(int)方法。
以下程序说明了上述方法: 程序 1:
```java // 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)); } } ```
Output:
```java A is a digit -> false 4 is a digit -> true
```
程序 2:
```java // 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."); } } } } ```
Output:
```java Digit found at : 4th position. Digit not present.
```
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java . lang . character . IsDigit(int CodePoint)是 Java 中的一个内置方法，用于确定指定的整数类型的 Unicode 代码点字符是否为数字。 一个字符要被接受为一个数字，几乎没有必须满足的条件。也就是说，如果由 getType(codepoint)提供的字符的一般类别类型是 DECIMAL_DIGIT_NUMBER，那么该字符就是一个数字。一些包含数字的 Unicode 字符范围:
从' \u0030 '到' \u0039' : ISO-LATIN-1 数字(' 0 '到' 9') 从' \u0660 '到' \u0669 ':阿拉伯-印度数字 从' \u06F0 '到' \u06F9 ':扩展阿拉伯-印度数字 从' \u0966 '到' \u096F ':梵文数字 从' \uFF10 '到' \uFF19 ':全幅
除了上述范围，许多其他字符范围也包含数字。
语法:
public static boolean isDigit(int codePoint)
参数:该方法接受整数类型的 unicode 字符参数码点作为参数，待测试。
返回值:这个方法返回一个布尔值。如果指定的字符是数字，则返回真，否则返回假。
以下程序说明了上述方法: 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));
}
}
Output:
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));
}
}
Output:
The codePoint cp1 is a digit -> false
The codePoint cp2 is a digit -> true
参考:https://docs . Oracle . com/javase/8/docs/API/Java/lang/character . html # isDigit-char-
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