Summary of methods for determining whether a string is a number in java

The example in this article summarizes Java's method of determining whether a string is a number. Share it with everyone for your reference, the details are as follows:

Method 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;
}

Method 2: Use regular expressions

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

Method 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;
}

I hope this article will be helpful to everyone in Java programming.

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