Character クラスの isDigit(int codePoint) メソッドは通常、指定された文字が数字であるかどうかを判断します。一般に、getType(codePoint) によって指定される一般カテゴリが DECIMAL_DIGIT_NUMBER である場合、文字は数字とみなされます。

構文

 public static boolean isDigit(int codePoint) 

パラメータ

上記のメソッドに必要なパラメータは 1 つだけです。

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a.) テストする必要がある Unicode 文字である codePoint。

戻り値

isDigit(int codePoint) メソッドは、指定された (または指定された) 文字が数字の場合、ブール値、つまり true を返します。それ以外の場合、メソッドは false を返します。

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.
'); } else{ System.out.print('The codePoint ''+codepoint1+'' is not a digit.
'); } if(check2){ System.out.print('The codePoint ''+codepoint2+'' is a digit.
'); } else{ System.out.print('The codePoint ''+codepoint2+'' is not a digit.
'); } if(check3){ System.out.print('The codePoint ''+codepoint3+'' is a digit.
'); } else{ System.out.print('The codePoint ''+codepoint3+'' is not a digit.
'); } if(check4){ System.out.print('The codePoint ''+codepoint4+'' is a digit.
'); } else{ System.out.print('The codePoint ''+codepoint4+'' is not a digit.
'); } if(check5){ System.out.print('The codePoint ''+codepoint5+'' is a digit.
'); } else{ System.out.print('The codePoint ''+codepoint5+'' is not a digit.
'); } } } 

出力：

 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. 

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 ); } } 

出力：

 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 

Character クラスの isDigit(char ch) メソッドは、通常、指定された文字が数字であるかどうかを判断します。

一般に、Character.getType(ch) によって指定される一般カテゴリが DECIMAL_DIGIT_NUMBER である場合、文字は数字とみなされます。

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注: 上記の方法では、補助文字を処理することはできません。すべての補助文字を含むすべての Unicode 文字をサポートするには、isdigital(int) メソッドを使用します。

構文

 public static boolean isDefined(char ch) 

パラメータ

上記のメソッドに必要なパラメータは 1 つだけです

戻り値

isDigit(char ch) メソッドはブール値、つまり、指定された (または指定された) 文字が数字の場合は true を返します。それ以外の場合、メソッドは false を返します。

Wordの透かし

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 ); } } 

出力：

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

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.
'); } else{ System.out.print('The character ''+value1+'' is not a digit.
'); } // 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.
'); } else{ System.out.print('The character ''+value2+'' is not a digit.
'); } } } 

出力：

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

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 ); } } 

出力：

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