注:问题是从json字符串创建数字流,最好使用正则表达式。请不要将此问题视为正则表达式上其他内容的重复。我的主要目标是阅读数字流。为此使用正则表达式是可选的。
我的目标是创建一个从大json字符串中读取的十进制数字数组,看起来像下面的示例。示例输入:
{
"item1": 102.119,
"item2": "unknown",
"item3": 200.12,
"item4": 1.08,
"item5": 0.04
}
预期输出:
我的数据= [102.119,200.12,1.08,0.04]
我尝试过的事情:
import java.util.ArrayList;
public class MyData {
public static void main(String[] args) {
String input = ("{\"item1\": 102.119,"
+ "\"item2\": \"unknown\","
+ "\"item3\": 200.12,"
+ "\"item4\": 1.08,"
+ "\"item5\": 0.04}"
);
ArrayList<Double> output = new ArrayList<>();
for(String s1 : input.split(",")) {
for(String s2: s1.split(":")) {
try {
output.add(Double.parseDouble(s2));
} catch(Exception e) {
System.out.println(e.toString() + " : " + s2 + " is not a number!");
}
}
}
System.out.println("\nMy Data = " + output.toString());
}
}
实际输出:
$ javac MyData.java
$ java MyData
java.lang.NumberFormatException: For input string: "{"item1"" : {"item1" is not a number!
java.lang.NumberFormatException: For input string: ""item2"" : "item2" is not a number!
java.lang.NumberFormatException: For input string: ""unknown"" : "unknown" is not a number!
java.lang.NumberFormatException: For input string: ""item3"" : "item3" is not a number!
java.lang.NumberFormatException: For input string: ""item4"" : "item4" is not a number!
java.lang.NumberFormatException: For input string: ""item5"" : "item5" is not a number!
java.lang.NumberFormatException: For input string: "0.04}" : 0.04} is not a number!
My Data = [102.119, 200.12, 1.08]
问题:
需要帮助:
您能否以更有效的方式帮助改进代码以读取所有十进制数字?您能否让我知道正则表达式模式匹配是否可以用于这种情况?
[最好使用现有的库,例如org.json或GSON来解析JSON。两者都提供了一个对象结构,您可以像当前解决方案一样循环和提取。
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