Java Character isDigit() 方法

2024年11月6日 | 阅读时长 5 分钟

Character 类的 isDigit(int codePoint) 方法通常用于确定给定的字符是否为数字。通常，如果字符的通用类别（由 getType(codePoint) 提供）是 DECIMAL_DIGIT_NUMBER，则该字符被视为数字。

语法

参数

上述方法只需要一个参数

a.) codePoint 是需要测试的 Unicode 字符。

返回值

isDigit(int codePoint) 方法返回一个布尔值，如果给定的（或指定的）字符是数字，则返回 true。否则，该方法返回 false。

示例 1

public class JavaCharacaterisDigitintcodePointExample1 {
public static void main(String[] args) {		
		// Initialize the codePoints.
		int codepoint1 = 55;
		int codepoint2 = 32;
		int codepoint3 = 121;
		int codepoint4 = 49;
		int codepoint5 = 200;	
		// Check whether a particular codePoint is a digit or not.
		boolean check1 = Character.isDigit(codepoint1);
		boolean check2 = Character.isDigit(codepoint2);
		boolean check3 = Character.isDigit(codepoint3);
		boolean check4 = Character.isDigit(codepoint4);
		boolean check5 = Character.isDigit(codepoint5);
		// Print the result.
		if(check1){
		System.out.print("The codePoint \'"+codepoint1+"\' is a digit.\n");
		}
		else{
		System.out.print("The codePoint \'"+codepoint1+"\' is not a digit.\n");
		}
		if(check2){
		System.out.print("The codePoint \'"+codepoint2+"\' is a digit.\n");
		}
		else{
		System.out.print("The codePoint \'"+codepoint2+"\' is not a digit.\n");
		}
		if(check3){
		System.out.print("The codePoint \'"+codepoint3+"\' is a digit.\n");
		}
		else{
		System.out.print("The codePoint \'"+codepoint3+"\' is not a digit.\n");
		}	
		if(check4){
		System.out.print("The codePoint \'"+codepoint4+"\' is a digit.\n");
		}
		else{
		System.out.print("The codePoint \'"+codepoint4+"\' is not a digit.\n");
		}
		if(check5){
		System.out.print("The codePoint \'"+codepoint5+"\' is a digit.\n");
		}
		else{
		System.out.print("The codePoint \'"+codepoint5+"\' is not a digit.\n");
		}	
	}
}

输出

The codePoint '55' is a digit.
The codePoint '32' is not a digit.
The codePoint '121' is not a digit.
The codePoint '49' is a digit.
The codePoint '200' is not a digit.

示例 2

public class JavaCharacaterisDigitintcodePointExample2 {
	  public static void main(String[] args) {
	     // Create four int primitives obj1, obj2, obj3 and obj4.
	      int obj1, obj2, obj3, obj4;
	     // Assign the values to obj1, obj2, obj3 and obj4.
	      obj1 = 0x06f8;
	      obj2 = 0x0432;
	      obj3 = 0x50;
	      obj4 = 0x0c12;
	     // Create four boolean primitives b1, b2, b3 and b4.
	      boolean b1, b2, b3, b4;
	     // Assign the isDigit method
	      b1 = Character.isDigit(obj1);
	      b2 = Character.isDigit(obj2);
	      b3 = Character.isDigit(obj3);
	      b4 = Character.isDigit(obj4);
	      String str1 = "The first object represents a digit :  " + b1;
	      String str2 = "The first object represents a digit :  " + b2;
	      String str3 = "The first object represents a digit :  " + b3;
	      String str4 = "The first object represents a digit :  " + b4;
	      // Print the values of b1, b2, b3 and b4.
	      System.out.println( str1 );
	      System.out.println( str2 );
	      System.out.println( str3 );
	      System.out.println( str4 );
	   }
}

输出

The first object represents a digit :  true
The first object represents a digit :  false
The first object represents a digit :  false
The first object represents a digit :  false

Java Character isDigit() 方法

Character 类的 isDigit(char ch) 方法通常用于确定给定的字符是否为数字。

通常，如果字符的通用类别（由 Character.getType(ch) 提供）是 DECIMAL_DIGIT_NUMBER，则该字符被视为数字。

注意：上述方法不能用于处理增补字符。为了支持所有 Unicode 字符，包括所有增补字符，我们可以使用 isdigit(int) 方法。

语法

参数

上述方法只需要一个参数

a.) 需要测试的字符。

返回值

isDigit(char ch) 方法返回一个布尔值，如果给定的（或指定的）字符是数字，则返回 true。否则，该方法返回 false。

示例 3

public class JavaCharacterisDigitExample3 {
	public static void main(String[] args) {
	   // Create three char primitives: obj1, obj2, and obj3.
	      char obj1, obj2, obj3;
	   // Assign the values to obj1, obj2 and obj3 respectively.
	      obj1 = ' ';
	      obj2 = '4';
	      obj3 = '8';
	   // Create three boolean primitives b1, b2 and b3.
	      boolean b1, b2,b3;
	   //Assign isDigit results of obj1, obj2 and obj3 to b1, b2, and b3 respectively.
	      b1 = Character.isDigit(obj1);
	      b2 = Character.isDigit(obj2);
	      b3 = Character.isDigit(obj3);
	      String str1 = "The digit '" +  obj1 +"' is:"+b1;
	      String str2 = "The digit '" +  obj2 +"' is:"+b2;
	      String str3 = "The digit '" +  obj3 +"' is:"+b3;
	   // Print the values of b1, b2 and b3.
	      System.out.println( str1 );
	      System.out.println( str2 );
	      System.out.println( str3 );
	   }
	}

输出

The digit ' ' is:false
The digit '4' is:true
The digit '8' is:true

示例 4

import java.util.Scanner;
  public class JavaCharacterisDigitExample4 {
    public static void main(String[] args) {	
      // Ask the user to enter the first character.
		System.out.print("Enter the first character:");	
     // Use scanner to get the user input.
		Scanner s1 = new Scanner(System.in);		
		char value1 = s1.nextLine().toCharArray()[0];
    // Check whether the input is digit or not.
		boolean check1 = Character.isDigit(value1);
    // Print the result
		if(check1){
		System.out.print("The character \'"+value1+"\' is a digit.\n");
		}
		else{
		System.out.print("The character \'"+value1+"\' is not a digit.\n");
		}
   // Ask the user to enter the second character.
		System.out.print("Enter the first character:");	
  // Use scanner to get the user input.
		Scanner s2 = new Scanner(System.in);	
		char value2 = s2.nextLine().toCharArray()[0];
    // Check whether the input is digit or not.
		boolean check2 = Character.isDigit(value2);
    // Print the result.
		if(check2){
		System.out.print("The character \'"+value2+"\' is a digit.\n");
			}
		else{
		System.out.print("The character \'"+value2+"\' is not a digit.\n");
	       }
       }
}

输出

Enter the first character: &
The character '&' is not a digit.
Enter the first character: 3
The character '3' is a digit.

示例 5

public class JavaCharacterisDigitExample5 {
	public static void main(String[] args) {
	   // Create four char primitives: obj1, obj2, obj3 and obj4.
	      char obj1, obj2, obj3, obj4;
	   // Assign the values to obj1, obj2, obj3 and obj4 respectively.
	      obj1 = 'A';
	      obj2 = '3';
	      obj3 = 'b';
	      obj4 = '6';
	  // Create four boolean primitives b1, b2, b3, and b4.
	      boolean b1, b2,b3,b4;
	  // Assign isDigit results of obj1, obj2, obj3, and obj4 to b1, b2 and b3 respectively.
	      b1 = Character.isDigit(obj1);
	      b2 = Character.isDigit(obj2);
	      b3 = Character.isDigit(obj3);
	      b4 = Character.isDigit(obj4);
	      String str1 = "The digit '" +  obj1 +"' is:"+b1;
	      String str2 = "The digit '" +  obj2 +"' is:"+b2;
	      String str3 = "The digit '" +  obj3 +"' is:"+b3;
	      String str4 = "The digit '" +  obj4 +"' is:"+b4;
	  // Print the values of b1, b2, b3 and b4.
	      System.out.println( str1 );
	      System.out.println( str2 );
	      System.out.println( str3 );
	      System.out.println( str4 );
	   }
	}

输出

The digit 'A' is:false
The digit '3' is:true
The digit 'b' is:false
The digit '6' is:true

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Java Character isDigit() 方法

语法

参数

返回值

示例 1

示例 2

Java Character isDigit() 方法

注意：上述方法不能用于处理增补字符。为了支持所有 Unicode 字符，包括所有增补字符，我们可以使用 isdigit(int) 方法。

语法

参数

返回值

示例 3

示例 4

示例 5

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Java Character isDigit() 方法

语法

参数

返回值

示例 1

示例 2

Java Character isDigit() 方法

注意：上述方法不能用于处理增补字符。为了支持所有 Unicode 字符，包括所有增补字符，我们可以使用 isdigit(int) 方法。

语法

参数

返回值

示例 3

示例 4

示例 5

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