在java中在字符串中添加数字
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Adding numbers within a string in java
提问by metelofe
How do I add two numbers within one string?
如何在一个字符串中添加两个数字？
I have:
我有：
String a = "(x+x)";
String lb = "2";
String b = a.replace("x", lb);
int c = ?
it outputs 2+2, how do I get it to add them together correctly into an integer?
它输出2+2，我如何让它正确地将它们加在一起成一个整数？
采纳答案by sushain97
While you can use a Java library to achieve this goal as mentioned in the comments, there issomething built into Java since version 6 which may be useful (but maybe a little overkill). I suggest this not because I believe it's particularly efficient but rather as an alternative to using a library.
虽然你可以使用Java库，以实现在评论中提到这个目标，还有是因为6版本，这可能是有用的（但也许有点矫枉过正）内置到Java的东西。我建议这样做不是因为我认为它特别有效，而是作为使用库的替代方法。
Use JavaScript:
使用 JavaScript：
import javax.script.ScriptEngineManager;
import javax.script.ScriptEngine;
ScriptEngine jsRuntime = new ScriptEngineManager().getEngineByName("javascript");
String expression = "2+2"; //The expression you would to evaluate.
double result = (Double) jsRuntime.eval(expression);
回答by rgettman
Use the Integer.parseIntmethodto parse a Stringinto an int, then add the values. Adding strings just concatenates them.
使用该Integer.parseInt方法将 a 解析String为 an int，然后添加值。添加字符串只是将它们连接起来。
回答by DT7
You can use parseInt()method.
您可以使用parseInt()方法。
回答by Dónal
It seems your question could be summarised as
看来你的问题可以概括为
How do I convert a String such as
"2+2"to the number4
如何将字符串转换为
"2+2"数字4
Here's a solution that uses only the standard Java libraries:
这是一个仅使用标准 Java 库的解决方案：
String sumExpression = "2+2";
String[] numbers = sumExpression.split("\+");
int total = 0;
for (String number: numbers) {
total += Integer.parseInt(number.trim());
}
// check our result
assert total == 4;
