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Topic: ！新手求解！(求 isNumberic)

1.！新手求解！(求 isNumberic)

Posted by: sealsealseal
Posted on: 2006-03-22 22:30

public class HH {
static boolean isNumberic(String num){
插入代碼
}
public static void main(String[] args) {
System.out.println(isNumberic("123"));
System.out.println(isNumberic("-123.23"));
System.out.println(isNumberic("0x123"));
System.out.println(isNumberic("12acb3"));
System.out.println(isNumberic("-aa123"));
}
输出：
true
true
false
false
false

2.Re:！新手求解！ [Re: sealsealseal]

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Posted by: zcjl
Posted on: 2006-03-23 00:30

没找到现成的isNumeric API
下面的代码纯粹是为了应付题目 ^_^

public static void main(String[] args) {
    System.out.println(isNumberic("123"));
    System.out.println(isNumberic("-123.23"));
    System.out.println(isNumberic("0x123"));
    System.out.println(isNumberic("12acb3"));
    System.out.println(isNumberic("-aa123"));
}

public static boolean isNumberic(String num) {
    try {
        Double.parseDouble(num);
        return true;
    } catch (NumberFormatException e) {
        return false;
    }
}

3.Re:！新手求解！(求 isNumberic) [Re: sealsealseal]	Copy to clipboard
Posted by: sealsealseal Posted on: 2006-03-23 07:48 謝謝~

4.Re:！新手求解！(求 isNumberic) [Re: sealsealseal]

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Posted by: suntao19830709
Posted on: 2006-03-23 17:41

这是apache的StringUtils的原码。


public static boolean isNumeric(String str) {
        if (str == null) {
            return false;
        }
        int sz = str.length();
        for (int i = 0; i < sz; i++) {
            if (Character.isDigit(str.charAt(i )) == false) {
                return false;
            }
        }
        return true;
    }

5.Re:！新手求解！(求 isNumberic) [Re: sealsealseal]

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Posted by: suntao19830709
Posted on: 2006-03-23 17:47

apache给出的注释


     * StringUtils.isNumeric(null)   = false
     * StringUtils.isNumeric("")     = true
     * StringUtils.isNumeric("  ")   = false
     * StringUtils.isNumeric("123")  = true
     * StringUtils.isNumeric("12 3") = false
     * StringUtils.isNumeric("ab2c") = false
     * StringUtils.isNumeric("12-3") = false
     * StringUtils.isNumeric("12.3") = false

6.Re:！新手求解！(求 isNumberic) [Re: sealsealseal]	Copy to clipboard
Posted by: why Posted on: 2006-03-23 18:10 http://jakarta.apache.org/commons/lang/api/org/apache/commons/lang/StringUtils.html#isNumeric(java.lang.String) 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.