Java中判断字符串是否为数字的五种方法

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

public static boolean isInteger(String str) {
Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");
return pattern.matcher(str).matches();
}

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

public final static boolean isNumeric(String s) {
if (s != null && !"".equals(s.trim()))
return s.matches("^[0-9]*$");
else
return false;
}

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;
}