What is the best way to extract this int from a string in Java?

问题

Here are examples of some input that I may be given

1,4
34,2
-99,20

etc.

Therefore negative values are included and 1, 2, 3, etc digits are possible. Commas are not the only delimiters, just an example. But Non integer values are the reason parseInt won't work. What can I code that will allow me to parse the above 3 inputs so that I get this?

1
34
-99

回答1:

Use this code:

String str = "1,4 34,2 -99,20";
String[] arr = str.split("\\D+(?<![+-])");
for (int i=0; i<arr.length; i+=2)
    System.out.println(Integer.parseInt(arr[i]));

OUTPUT:

1
34
-99

回答2:

You can use regular expressions (regex).

A simple example of breaking with commas:

String[] values = string.split(",")
for (String a : values) {
    Integer.parseInt(a);
}

回答3:

This is a very open question... I will suggest that you first go through your string, and format all the numbers correctly substituting all the commas for dots... Then you need to split it, and then you need to parse each value.

For each step you can find a lot of help googling.

ie.

Step 1. String substitution java
Step 2. String split java
Step 3. String to int java

回答4:

You can replace all characters except digits with an empty string and then do a parseInt

String intStr = inputStr.replaceAll("[^0-9]+","");
int i = Integer.parseInt(intStr);

回答5:

If you only use commas, you could do

String numbers = "1,34,-99";
String[] splitNums = numbers.split(",");
int[] ints = null;
for(int i = 0; i < splitNums.length(); i++) 
{
    ints[i] = Integer.valueOf(splitNums[i]);
}

回答6:

If you want input to be valid only if there is a delimiter, use "([\\-0-9]*)[,]+.*" instead.

If you want to add additional delimiters, e.g. :, add to the delimiter set, e.g. "([\\-0-9]*)[,|:]+.*"

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Test {
   public static void main(String args[]) {
        try {
            String s1 = "-99,20";
            System.out.println(getNumber(s1));

            s1 = "1,4";
            System.out.println(getNumber(s1));
        } catch (Exception e) {
            e.printStackTrace();
        }

    }

    public static int getNumber(String s1) throws Exception {
        Pattern pattern = Pattern.compile("([\\-0-9]*)[,]*.*");
        Matcher m = pattern.matcher(s1);
        if(m.find()) {
            return Integer.parseInt(m.group(1));
        } 

        throw new Exception("Not valid input");
    }
}

来源：https://stackoverflow.com/questions/9180849/what-is-the-best-way-to-extract-this-int-from-a-string-in-java

标签

java

string

int

parseint