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正規表現で整数と小数を判別する

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Javaで文字列の整数・小数判定を行った際の備忘録

##やりたいこと
数字と小数点のみで構成されている文字列を正として扱いたい。(指数表記等を除く)
Double.parsedouble(str)メソッドだと、指数表記である2.4e+8NaNInfinityがパースされてしまうため、正規表現で判別を行いました。

##前提条件
jdk1.8.0_40

#結果
^-?(0|[1-9]\d*)(\.\d+|)$
##テスト

テストコード
List<String> targets = Arrays.asList("0","-0","0.8","0.878","1","-1","1.1",
    "1.123","544","42.195","000","000.0","2.4e+8","3.1e-2","-6.75e-7",
    "0X02.Bp-1","1.","155.","000.0","-0.","-0000.","0x07","A","1",
    "-","NaN","Infinity","-Infinity");
String regex = "^-?(0|[1-9]\\d*)(\\.\\d+|)$";
Pattern p = Pattern.compile(regex);
for(String s : targets){
  Matcher matcher = p.matcher(s);
  if(matcher.matches())
    System.out.println("match! : " + s);
  else
    System.out.println("対象外 : " + s);
}

テスト対象は適当です。

result
match! : 0
match! : -0
match! : 0.8
match! : 0.878
match! : 1
match! : -1
match! : 1.1
match! : 1.123
match! : 544
match! : 42.195
対象外 : 000
対象外 : 000.0
対象外 : 2.4e+8
対象外 : 3.1e-2
対象外 : -6.75e-7
対象外 : 0X02.Bp-1
対象外 : 1.
対象外 : 155.
対象外 : 000.0
対象外 : -0.
対象外 : -0000.
対象外 : 0x07
対象外 : A
対象外 : 1
対象外 : -
対象外 : NaN
対象外 : Infinity
対象外 : -Infinity
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