java中验证字符串是不是数字的四种方法
java\u4e2d\u5224\u65ad\u5b57\u7b26\u4e32\u662f\u5426\u6570\u5b57\u7684\u4e24\u79cd\u65b9\u6cd5\u5224\u65ad\u5b57\u7b26\u4e32\u662f\u4e0d\u662f\u6570\u5b57\uff0c\u5927\u5bb6\u53ef\u80fd\u4f1a\u7528\u4e00\u4e9bjava\u81ea\u5e26\u7684\u65b9\u6cd5\uff0c\u4e5f\u6709\u53ef\u80fd\u7528\u5176\u4ed6\u602a\u5f02\u7684\u62db\u5f0f\uff0c\u6bd4\u5982\u5224\u65ad\u662f\u4e0d\u662f\u6574\u578b\u6570\u5b57\uff0c\u5c06\u5b57\u7b26\u4e32\u5f3a\u5236\u8f6c\u6362\u6210\u6574\u578b\uff0c\u4e0d\u662f\u6570\u5b57\u7684\u5c31\u4f1a\u629b\u51fa\u9519\u8bef\uff0c\u90a3\u4e48\u5c31\u4e0d\u662f\u6574\u578b\u7684\u4e86\u3002\u4f46\u672c\u6587\u4ecb\u7ecd\u7684\u6bd4\u8f83\u597d\u7684\u4e24\u79cd\u65b9\u6cd5\uff1a
1\u3002java\u7c7b\u5e93\u81ea\u5e26\u7684\u65b9\u6cd5\uff1a
public boolean isNum(String msg){
if(java.lang.Character.isDigit(msg.charAt(0))){
return true;}return false;}�0�2�0�2\u66f4\u65b0\uff1a\u53d1\u73b0\u4ee5\u4e0a\u65b9\u6cd5\u5199\u5f97\u4e0d\u591f\u5230\u4f4d\uff0c\u73b0\u5728\u5c31\u6539\u4e3a\u4e0b\u9762\u7684\u7b80\u5355\u8bf4\u660e\u4e86\uff0c\u81f3\u4e8e\u5177\u4f53\u7684\u65b9\u6cd5\u5b9e\u73b0\u5b57\u7b26\u4e32\u5224\u65ad\u662f\u5426\u6570\u5b57\u5c31\u4e0d\u5199\u4e86\u3002
java.lang.Character.isDigit(char ch) boolean
isDigit \u53ea\u80fd\u4f5c\u7528\u4e8echar\uff0c\u6240\u4ee5\u5224\u65ad\u5b57\u7b26\u4e32\u662f\u5426\u4e3a\u6570\u5b57\uff0c\u8981\u4e00\u4e2a\u4e00\u4e2a\u62ff\u51fachar\u8fdb\u884c\u5224\u65ad\u3002
2\u3002\u7528\u6b63\u5219\u8868\u8fbe\u5f0f
\u9996\u5148\u8981import java.util.regex.Pattern \u548c java.util.regex.Matcher
\u8fd9\u4e24\u4e2a\u5305\uff0c\u63a5\u4e0b\u6765\u662f\u4ee3\u7801
public boolean isNumeric(String str){Pattern pattern = Pattern.compile(\u201d[0-9]*\u201d);
Matcher isNum = pattern.matcher(str);
if( !isNum.matches() ){return false;}return true;}�0�2
3\u3002\u7528\u6b63\u5219\u8868\u8fbe\u5f0f
1.\u4f7f\u7528Character.isDigit(char)\u5224\u65ad
char num[] = str.toCharArray();//\u628a\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u5b57\u7b26\u6570\u7ec4
StringBuffer title = new StringBuffer();//\u4f7f\u7528StringBuffer\u7c7b\uff0c\u628a\u975e\u6570\u5b57\u653e\u5230title\u4e2d
StringBuffer hire = new StringBuffer();//\u628a\u6570\u5b57\u653e\u5230hire\u4e2d
for (int i = 0; i < num.length; i++) {
// \u5224\u65ad\u8f93\u5165\u7684\u6570\u5b57\u662f\u5426\u4e3a\u6570\u5b57\u8fd8\u662f\u5b57\u7b26
if (Character.isDigit(num[i])) {\u628a\u5b57\u7b26\u4e32\u8f6c\u6362\u4e3a\u5b57\u7b26\uff0c\u518d\u8c03\u7528Character.isDigit(char)\u65b9\u6cd5\u5224\u65ad\u662f\u5426\u662f\u6570\u5b57\uff0c\u662f\u8fd4\u56deTrue\uff0c\u5426\u5219False
hire.append(num[i]);// \u5982\u679c\u8f93\u5165\u7684\u662f\u6570\u5b57\uff0c\u628a\u5b83\u8d4b\u7ed9hire} else {title.append(num[i]);// \u5982\u679c\u8f93\u5165\u7684\u662f\u5b57\u7b26\uff0c\u628a\u5b83\u8d4b\u7ed9title}}}
2.\u4f7f\u7528\u7c7b\u578b\u8f6c\u6362\u5224\u65adtry {String str="123abc";
int num=Integer.valueOf(str);//\u628a\u5b57\u7b26\u4e32\u5f3a\u5236\u8f6c\u6362\u4e3a\u6570\u5b57
return true;//\u5982\u679c\u662f\u6570\u5b57\uff0c\u8fd4\u56deTrue
} catch (Exception e) {
return false;//\u5982\u679c\u629b\u51fa\u5f02\u5e38\uff0c\u8fd4\u56deFalse}
3.\u4f7f\u7528\u6b63\u5219\u8868\u8fbe\u5f0f\u5224\u65ad
String str = "";
boolean isNum = str.matches("[0-9]+");
//+\u8868\u793a1\u4e2a\u6216\u591a\u4e2a\uff08\u5982"3"\u6216"225"\uff09\uff0c*\u8868\u793a0\u4e2a\u6216\u591a\u4e2a\uff08[0-9]*\uff09\uff08\u5982""\u6216"1"\u6216"22"\uff09\uff0c?\u8868\u793a0\u4e2a\u62161\u4e2a([0-9]?)(\u5982""\u6216"7")
ps\uff1a\u8fd9\u4e2a\u65b9\u6cd5\u53ea\u80fd\u7528\u4e8e\u5224\u65ad\u662f\u5426\u662f\u6b63\u6574\u6570
1。java类库自带的方法：
public boolean isNum(String msg){
if(java.lang.Character.isDigit(msg.charAt(0))){
return true;}return false;}0202更新：发现以上方法写得不够到位，现在就改为下面的简单说明了，至于具体的方法实现字符串判断是否数字就不写了。
java.lang.Character.isDigit(char ch) boolean
isDigit 只能作用于char，所以判断字符串是否为数字，要一个一个拿出char进行判断。
2。用正则表达式
首先要import java.util.regex.Pattern 和 java.util.regex.Matcher
这两个包，接下来是代码
public boolean isNumeric(String str){Pattern pattern = Pattern.compile(”[0-9]*”);
Matcher isNum = pattern.matcher(str);
if( !isNum.matches() ){return false;}return true;}02
3。用正则表达式
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绛旓細StringBuffer title = new StringBuffer();//浣跨敤StringBuffer绫伙紝鎶婇潪鏁板瓧鏀惧埌title涓 StringBuffer hire = new StringBuffer();//鎶婃暟瀛楁斁鍒癶ire涓 for (int i = 0; i < num.length; i++) { // 鍒ゆ柇杈撳叆鐨勬暟瀛楁槸鍚涓烘暟瀛楄繕鏄瓧绗 if (Character.isDigit(num[i])) {鎶瀛楃涓杞崲涓哄瓧绗︼紝...
绛旓細public class Testone { public static void main(String[] args){ String str="123456";boolean result=str.matches("[0-9]+");if (result == true) { System.out.println("璇瀛楃涓叉槸绾鏁板瓧");}else{System.out.println("璇ュ瓧绗︿覆涓嶆槸绾暟瀛");}}}鏂规硶浜岋細鍒╃敤Pattern.import java.util...
绛旓細鍒ゆ柇瀛楃涓叉槸涓嶆槸鏁板瓧锛屽ぇ瀹跺彲鑳戒細鐢ㄤ竴浜沯ava鑷甫鐨勬柟娉曪紝涔熸湁鍙兘鐢ㄥ叾浠栨紓鐨勬嫑寮忥紝姣斿鍒ゆ柇鏄笉鏄暣鍨嬫暟瀛楋紝灏嗗瓧绗︿覆寮哄埗杞崲鎴愭暣鍨嬶紝涓嶆槸鏁板瓧鐨勫氨浼氭姏鍑洪敊璇紝閭ｄ箞灏变笉鏄暣鍨嬬殑浜嗐備絾鏈枃浠嬬粛鐨勬瘮杈冨ソ鐨勪袱绉嶆柟娉曪細1銆俲ava绫诲簱鑷甫鐨勬柟娉曪細public boolean isNum(String msg){ if(java.lang.Character.i...
绛旓細ava涓鍒ゆ柇瀛楃涓叉槸鍚涓鏁板瓧鐨勬柟娉:1.鐢JAVA鑷甫鐨勫嚱鏁 public static boolean isNumeric(String str){ for (int i = 0; i < str.length(); i++){ System.out.println(str.charAt(i));if (!Character.isDigit(str.charAt(i))){ return false;} } return true;} 2.鐢ㄦ鍒欒〃杈惧紡 棣栧厛瑕...
绛旓細class Testone {public static void main(String[] args){String str="123456";boolean result=str.matches("[0-9]+");if (result == true) {System.out.println("璇瀛楃涓叉槸绾鏁板瓧");}else{System.out.println("璇ュ瓧绗︿覆涓嶆槸绾暟瀛");}}}鏂规硶浜岋細鍒╃敤Pattern.import java.util.regex....
绛旓細绋嬪簭灏嗗鍏舵槸鍚︿负鏁板瓧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();//鑾峰彇鐢ㄦ埛杈撳叆鐨勯噾棰瀛楃涓booleanisnum=NumberUtils.isNumber(text);//鍒ゆ柇鏄笉鏄暟瀛if(isnum){//杈撳嚭姝ｇ‘鎻愮ず淇℃伅showMessageDialog(null,"杈撳叆姝ｇ‘锛...
绛旓細Java涓鍒ゆ柇瀛楃涓叉槸鍚鍏鏄暟瀛锛氬彲浠ヤ娇鐢ㄦ鍒欒〃杈惧紡锛歱ublic boolean isNumeric(String str) { Pattern pattern = Pattern.compile("[0-9]*"); Matcher isNum = pattern.matcher(str); if (!isNum.matches()) { return false; } return true; }浣嗘槸杩欎釜鏂规硶骞朵笉瀹夊叏锛屾病鏈...
绛旓細param str 浼犲叆鐨勫瓧绗︿覆 return 鏄暣鏁拌繑鍥瀟rue,鍚﹀垯杩斿洖false / public static boolean isInteger(String str) { Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");return pattern.matcher(str).matches();} //鏂规硶涓夛細public static boolean isNumeric(String str){ Pattern pattern = ...
绛旓細鐢ㄦ鍒欒〃杈惧紡鍒ゆ柇濂戒簡:String str="123";boolean b=str.matches("[0-9]+");濡傛灉b鏄痜alse灏辫〃绀哄叾涓惈鏈夐潪鏁板瓧,濡傛灉涓簍rue灏辫〃绀哄叾涓叏鏄暟瀛.+琛ㄧず鍖归厤1鍒版棤绌锋.
