Java怎样判断输入是否为数字 Java怎样判断输入是否为数字
java\u5c06\u6570\u5b57\u8f93\u5165\u7a0b\u5e8f\uff0c\u5982\u4f55\u5224\u65ad\u662f\u5426\u4e3a\u5947\u6570\u6216\u5076\u6570import java.util.Scanner;
public class Main{
public static void main(String args[]){
Scanner input=new Scanner(System.in);
int a;
System.out.print("\u8bf7\u8f93\u5165\u4e00\u4e2a\u6574\u6570\uff1a");
a=input.nextInt();
if(a % 2 == 0){ //\u5224\u65ad\u662f\u5076\u6570\u8fd8\u662f\u5947\u6570
// \u662f\u5076\u6570
}
else
// \u662f\u5947\u6570
}
}
}
\u53ef\u4ee5\u7528\u6b63\u5219\u8868\u8fbe\u5f0f\uff0c\u8fd8\u53ef\u4ee5\u76f4\u63a5\u8fdb\u884c\u8f6c\u6362\uff0c\u4f8b\u5982Integer.parse(n)\uff0c
\u5982\u679c\u8f6c\u6362\u5931\u8d25\u5219\u4e0d\u662f\u6570\u5b57\uff0c\u5b9a\u4e49\u4e00\u4e2a\u5b57\u7b26\u4e32"0123456789"\uff0c\u7136\u540e\u628a\u76ee\u6807\u5b57\u7b26\u4e32\u7684\u6bcf\u4e2a\u5b57\u7b26\u53d6\u51fa\u6765\uff0c\u5982\u679c\u4ed6\u6709\u4e00\u4e2aindexOf("0123456789")<0\u7684\u8bdd\uff0c\u5219\u8868\u793a\u4e0d\u662f\u3002\u5f53\u7136\u8fd9\u662f\u9488\u5bf9\u6b63\u6574\u6570\u7684\u60c5\u51b5\uff0c\u6d6e\u70b9\u6570\uff0c\u8d1f\u6570\u7a0d\u5fae\u6539\u4e00\u4e0b
\u4e0b\u9762\u662f\u5b9e\u4f8b\u4ee3\u7801\uff1a
public class CharTest {
public CharTest() {
}
public static void main(String args[]) {
String s = "123abc";
for (int i=0;i<s.length();i++) {
char ch = s.charAt(i);
System.out.println(ch + " is digit? " + Character.isDigit(ch));
System.out.println(ch + " is digit? " + (ch >= '0' && ch <= '9'));
}
}
}
可以用正则表达式
绛旓細if (Character.isDigit(num[i])) {鎶婂瓧绗︿覆杞崲涓哄瓧绗︼紝鍐嶈皟鐢–haracter.isDigit(char)鏂规硶鍒ゆ柇鏄惁鏄暟瀛楋紝鏄繑鍥濼rue锛屽惁鍒橣alse hire.append(num[i]);// 濡傛灉杈撳叆鐨勬槸鏁板瓧锛屾妸瀹冭祴缁檋ire} else {title.append(num[i]);// 濡傛灉杈撳叆鐨勬槸瀛楃锛屾妸瀹冭祴缁檛itle}}} 2.浣跨敤绫诲瀷杞崲鍒ゆ柇try {Strin...
绛旓細浣犲彲浠ョ敤try{}catch(){}寮傚父鏈哄埗锛屾妸浣犱紶鍏ョ殑瀛楃涓茶浆鎹㈡垚鏁板瓧锛屽鏋滃彂鐢熷紓甯稿氨涓鏄暟瀛锛屾病鏈夊彂鐢熷紓甯稿垯鏄暟瀛
绛旓細绛旀锛氬彲浠ヤ娇鐢↗ava涓殑姝ｅ垯琛ㄨ揪寮忔潵鍒ゆ柇瀛楃涓叉槸鍚﹀叏閮ㄤ负鏁板瓧銆傚叿浣撳彲浠ヤ娇鐢╜matches`鏂规硶鍜屾鍒欒〃杈惧紡`"^[0-9]+$"`鏉ュ垽鏂傚鏋滆繑鍥瀈true`锛屽垯琛ㄧず瀛楃涓插叏閮ㄤ负鏁板瓧锛涘鏋滆繑鍥瀈false`锛屽垯琛ㄧず瀛楃涓蹭笉鍏ㄦ槸鏁板瓧銆傝缁嗚В閲婏細1. 姝ｅ垯琛ㄨ揪寮忕畝浠嬶細姝ｅ垯琛ㄨ揪寮忔槸涓绉嶅己澶х殑鏂囨湰澶勭悊宸ュ叿锛屽畠浣跨敤鐗瑰畾鐨勬ā寮忔潵...
绛旓細姝ｅ垯鏄竴绉嶏紝杩樺彲浠ョ洿鎺ヨ繘琛岃浆鎹紝渚嬪Integer.parse(n)锛屽鏋滆浆鎹㈠け璐ュ垯涓嶆槸鏁板瓧锛岃繕鍙互瀹氫箟涓涓瓧绗︿覆"0123456789"锛岀劧鍚庢妸鐩爣瀛楃涓茬殑姣忎釜瀛楃鍙栧嚭鏉ワ紝濡傛灉浠栨湁涓涓猧ndexOf("0123456789")<0鐨勮瘽锛屽垯琛ㄧず涓嶆槸銆傚綋鐒惰繖鏄拡瀵规鏁存暟鐨勬儏鍐碉紝娴偣鏁帮紝璐熸暟绋嶅井鏀逛竴涓 ...
绛旓細java.lang.Character.isDigit(char ch) boolean isDigit 鍙兘浣滅敤浜巆har锛屾墍浠ュ垽鏂瓧绗︿覆鏄惁涓烘暟瀛楋紝瑕佷竴涓竴涓嬁鍑篶har杩涜鍒ゆ柇銆2銆傜敤姝ｅ垯琛ㄨ揪寮 棣栧厛瑕乮mport java.util.regex.Pattern 鍜 java.util.regex.Matcher 杩欎袱涓寘锛屾帴涓嬫潵鏄唬鐮 public boolean isNumeric(String str){Pattern pattern = ...
绛旓細鍒ゆ柇鏄惁鏄暟瀛锛欳haracter.isDigit(char )鍒ゆ柇鏄惁鏄崟鏁帮細x%2 == 1 鍒ゆ柇鏄惁鏄瓧绗︼細Character.isLetter(char )
绛旓細銆愬疄鐜拌繃绋嬨戝湪Eclipse涓柊寤洪」鐩瓹heckNumber锛屽苟鍦ㄥ叾涓垱寤轰竴涓狢heckNumber.java鏂囦欢銆傚湪璇ョ被鐨勪富鏂规硶涓垱寤烘爣鍑杈撳叆娴佺殑鎵弿鍣ㄥ璞★紝鎺ユ敹鐢ㄦ埛杈撳叆鐨勯噾棰濄傜▼搴忓皢瀵瑰叾鏄惁涓烘暟瀛杩涜鍒ゆ柇骞惰緭鍑烘彁绀虹粨鏋溿傛牳蹇冧唬鐮佸涓嬫墍绀猴細protectedvoiddo_button_actionPerformed(ActionEvente){Stringtext=textField.getText();//...
绛旓細杩欓噷鏄Java鍚庡彴楠岃瘉銆俻ublic static void main(String[] args){ //target鏄粠鏂囨湰妗嗕紶鏉ョ殑鏁版嵁銆傝繖閲岃繘琛屾ā鎷烻tring target = "22221";//濡傛灉涓簍rue锛屽垯鏄暟瀛锛屽惁鍒欎笉鏄係ystem.out.println(isNumeric(target));}/** * 姝ｅ垯琛ㄨ揪寮忥細鍒ゆ柇鏄惁鏁板瓧 * @param str * @return */public static b...
绛旓細鏁 String value = "-23423.333";//涓句緥 鐢―ouble 瑙ｆ瀽鍒ゆ柇鏄惁涓烘暟瀛锛屽鏋滄姏鍑哄紓甯搁鍑猴紝姝ｇ‘鎺ョ潃瑙ｆ瀽鏄惁涓烘暣鏁.value.indexOf(".")>-1琛ㄧず涓哄皬鏁/*鍝曞儚3.00杩欐牱鐨勬暟鍚屾牱鏄皬鏁*/锛==-1琛ㄧず涓烘暣鏁般傛帴鐫鐢╲alue.indexOf("-")鍒ゆ柇鏄惁涓鸿礋鏁般傛晥鐜囩浉瀵逛簬瑙ｆ瀽鎴愭暣鏁拌楂樺緢澶氥
绛旓細鏂规硶涓锛氬埄鐢ㄦ鍒欒〃杈惧紡public class Testone {public static void main(String[] args){String str="123456";boolean result=str.matches("[0-9]+");if (result == true) {System.out.println("璇ュ瓧绗︿覆鏄绾鏁板瓧");}else{System.out.println("璇ュ瓧绗︿覆涓嶆槸绾暟瀛");}}}鏂规硶浜岋細鍒╃敤Pattern....
