Java如何判断输入的是字符还是数字？

用JAVA自带的函数：

public static boolean isNumeric(String str)

for (int i = 0; i <返枣 str.length(); i++)

System.out.println(str.charAt(i));

if (!Character.isDigit(str.charAt(i)))

return false;

用正则表达式：

首先要import java.util.regex.Pattern 和 java.util.regex.Matcher

public boolean isNumeric(String str)

Pattern pattern = Pattern.compile("[0-9]*");

Matcher isNum = pattern.matcher(str);

if( !isNum.matches() )

return false;

使用org.apache.commons.lang：

org.apache.commons.lang.StringUtils;

boolean isNunicodeDigits=StringUtils.isNumeric("敏世汪aaa123456789");

http://jakarta.apache.org/commons/lang/api-release/index.html下面的解释:

isNumeric

public static boolean isNumeric(String str)Checks if the String contains only unicode digits. A decimal point is not a unicode digit and returns false.

null will return false. An empty String ("") will return true.

StringUtils.isNumeric(null)   = false

StringUtils.isNumeric("")     = true

StringUtils.isNumeric("  桥仔")   = false

StringUtils.isNumeric("123")  = true

StringUtils.isNumeric("12 3") = false

StringUtils.isNumeric("ab2c") = false

StringUtils.isNumeric("12-3") = false

StringUtils.isNumeric("12.3") = false

Parameters:

str - the String to check, may be null

Returns:

true if only contains digits, and is non-null