Java determines whether it is a number

Java method to determine whether it is a number:

1. Use the function that comes with JAVA

public static boolean isNumeric(String str){ 
  for (int i = str.length();--i>=0;){   
   if (!Character.isDigit(str.charAt(i))){ 
    return false; 
   } 
  } 
  return true; 
}

2. Use regular expressions

public static boolean isNumeric(String str){ 
    Pattern pattern = Pattern.compile("[0-9]*"); 
    return pattern.matcher(str).matches();    
}

3. Use ascii code

public static boolean isNumeric(String str){ 
   for(int i=str.length();--i>=0;){ 
      int chr=str.charAt(i); 
      if(chr<48 || chr>57) 
         return false; 
   } 
   return true; 
}

4. Capture NumberFormatException

public static boolean isNumeric00(String str)
{  try{
   　　Integer.parseInt(str);
   　　return true;
  }catch(NumberFormatException e)
  {
 　　System.out.println("异常：\"" + str + "\"不是数字/整数...");
 　　return false;
  }
}

For more java knowledge, please pay attention to java basic tutorial.

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