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 tojava basic tutorial.

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