从Java中的长json字符串中获取十进制数流_Java_Arrays_Json_Stream_Double

从Java中的长json字符串中获取十进制数流

java arrays json stream

从Java中的长json字符串中获取十进制数流,java,arrays,json,stream,double,Java,Arrays,Json,Stream,Double,注意：问题是从json字符串创建数字流，最好使用正则表达式。请不要把这个问题看成是正则表达式的另一个复制品。我的主要目标是阅读一连串的数字。为此目的使用正则表达式是可选的我的目标是创建一个从一个大json字符串读取的十进制数数组，如下图所示输入示例： { "item1": 102.119, "item2": "unknown", "item3": 200.12, "item4": 1.08, "item5": 0.04 } import java

注意：问题是从json字符串创建数字流，最好使用正则表达式。请不要把这个问题看成是正则表达式的另一个复制品。我的主要目标是阅读一连串的数字。为此目的使用正则表达式是可选的

我的目标是创建一个从一个大json字符串读取的十进制数数组，如下图所示

输入示例：

 {
    "item1": 102.119,
    "item2": "unknown",
    "item3": 200.12,
    "item4": 1.08,
    "item5": 0.04
 }

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());
    }
}

$ 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]

预期输出：

 {
    "item1": 102.119,
    "item2": "unknown",
    "item3": 200.12,
    "item4": 1.08,
    "item5": 0.04
 }

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());
    }
}

$ 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]

我的数据=[102.119200.12,1.08,0.04]

我的尝试：

 {
    "item1": 102.119,
    "item2": "unknown",
    "item3": 200.12,
    "item4": 1.08,
    "item5": 0.04
 }

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());
    }
}

$ 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：

 {
    "item1": 102.119,
    "item2": "unknown",
    "item3": 200.12,
    "item4": 1.08,
    "item5": 0.04
 }

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());
    }
}

$ 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]

最后的数字0.04不会读取到数据数组中

在大型输入集上执行for的两个循环需要很长时间

需要帮助：

{ "item1": 102.119, "item2": "unknown", "item3": 200.12, "item4": 1.08, "item5": 0.04 }

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()); } }

$ 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]
您能否帮助改进代码，以更有效的方式读取所有十进制数

您能告诉我正则表达式模式匹配是否可用于此场景吗？
尝试使用此正则表达式：

/: (\d+(?:\.\d+))/

对于字符串拆分和正则表达式，都存在一些令人讨厌的边缘情况。如果您不能完全控制JSON，我不建议您尝试这样做
最好使用org.json或GSON等现有库来解析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它

也许这对你有帮助

/: (\d+\.\d+)/

嗨，伊利亚，谢谢你。我使用网站尝试了给定的正则表达式-/：（\d+（？\。\d+））/，但正则表达式与十进制数不匹配。（[\d]+）（[\d]+）的正则表达式模式已与数字匹配。我会试试这个。啊，对不起，我忘了
：
，这个
：（\d+（？：\。\d+）/
将匹配十进制数字。我是罗兰，谢谢你分享解析json的链接。我会试试的。别忘了还有一个关于Java的，在上可用的。我不明白为什么这个问题被认为是regexp的重复。我想从json中将数字作为流读取，最好使用regexp。我现在找不到答案，因为这个问题作为一个重复问题关闭。有人能帮我重新打开这个问题，这样我就能得到答案吗？