java中判断字符串是否为纯数字

Question

如题所述

Answer 1

方法一：利用正则表达式public class Testone {public static void main(String[] args){String str="123456";boolean result=str.matches("[0-9]+");if (result == true) {System.out.println("该字符串是纯数字");}else{System.out.println("该字符串不是纯数字");}}}方法二：利用Pattern.import java.util.regex.Matcher;import java.util.regex.Pattern;public class Testone {public static void main(String[] args){String str="123456";Pattern pattern = Pattern.compile("[0-9]{1,}");Matcher matcher = pattern.matcher((CharSequence)str);boolean result=matcher.matches();System.out.println("该字符串是纯数字");}else{System.out.println("该字符串不是纯数字");}}}

Answer 2

方法一：利用正则表达式
public class Testone {
public static void main(String[] args){
String str="123456";
boolean result=str.matches("[0-9]+");
if (result == true) {
System.out.println("该字符串是纯数字");}else{System.out.println("该字符串不是纯数字");}}}方法二：利用Pattern.
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Testone {
public static void main(String[] args){
String str="123456";
Pattern pattern = Pattern.compile("[0-9]{1,}");
Matcher matcher = pattern.matcher((CharSequence)str);
boolean result=matcher.matches();
System.out.println("该字符串是纯数字");}else{System.out.println("该字符串不是纯数字");}}}

Answer 3

java中判断字符串是否为纯数字的方法如下：
方法一：Pattern语句
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Testone {
public static void main(String[ ] args){
String str="123456";
Pattern pattern = Pattern.compile("[0-9]{1,}");
Matcher matcher = pattern.matcher((CharSequence)str);
boolean result=matcher.matches();
if (result == true) {
System.out.println("该字符串是纯数字");
}
else{
System.out.println("该字符串不是纯数字");
}
}
}
方法二：正则表达式
<span style="white-space:pre"></span>
public static boolean isNumber(String str){
String reg = "^[0-9]+(.[0-9]+)?$";
return str.matches(reg);
}

Answer 4

//方法一：用JAVA自带的函数
public static boolean isNumeric(String str)
{ for (int i = str.length();--i>=0;)
{
if (!Character.isDigit(str.charAt(i)))
{
return false;6
}
}
return true;
}

/*方法二：推荐，速度最快
* 判断是否为整数
* @param str 传入的字符串
* @return 是整数返回true,否则返回false
*/
public static boolean isInteger(String str) {
Pattern pattern = Pattern.compile("^[-\\+]?[\\d]*$");
return pattern.matcher(str).matches();
}
//方法三：public static boolean isNumeric(String str){
Pattern pattern = Pattern.compile("[0-9]*"); return pattern.matcher(str).matches();
}

//方法四：public final static boolean isNumeric(String s) { if (s != null && !"".equals(s.trim())) return s.matches("^[0-9]*$"); else
return false;
}
//方法五：用ascii码 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;
}本回答被网友采纳

Answer 5

方法一：利用正则表达式
public class Testone {
public static void main(String[] args){
String str="123456";
boolean result=str.matches("[0-9]+");
if (result == true) {
System.out.println("该字符串是纯数字");}else{System.out.println("该字符串不是纯数字");}}}方法二：利用Pattern.
import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Testone {
public static void main(String[] args){
String str="123456";
Pattern pattern = Pattern.compile("[0-9]{1,}");
Matcher matcher = pattern.matcher((CharSequence)str);
boolean result=matcher.matches();