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Java判断输入是否为数字-jsp教程入门教程

public class CharTest {
  public CharTest() {
  }
  public static void main(String args[]) {
  String s = "123abc";
  for (int i=0;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"));
  }
  }
}

方法二

if(str==null || "".equals(str.trim())){
return true;
}
Pattern pattern = Pattern.compile("[0-9]*");
Matcher isNum = pattern.matcher(str.trim());
if(isNum.matches()){
System.out.println("是一个数字");
}else{
System.out.println("不是一个数字");
}

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