How do I convert a String to an int in Java?

How can I convert a String to an int in Java?

My String contains only numbers, and I want to return the number it represents.

For example, given the string "1234" the result should be the number 1234 .

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String myString = "1234";
int foo = Integer.parseInt(myString);

有关更多信息，请参阅Java文档。

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For example, here are two ways:

Integer x = Integer.valueOf(str);
// or
int y = Integer.parseInt(str);

There is a slight difference between these methods:

valueOf returns a new or cached instance of java.lang.Integer

parseInt returns primitive int .

The same is for all cases: Short.valueOf / parseShort , Long.valueOf / parseLong , etc.

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Well, a very important point to consider is that the Integer parser throws NumberFormatException as stated in Javadoc.

int foo;
String StringThatCouldBeANumberOrNot = "26263Hello"; //will throw exception
String StringThatCouldBeANumberOrNot2 = "26263"; //will not throw exception
try {
      foo = Integer.parseInt(StringThatCouldBeANumberOrNot);
} catch (NumberFormatException e) {
      //Will Throw exception!
      //do something! anything to handle the exception.
}

try {
      foo = Integer.parseInt(StringThatCouldBeANumberOrNot2);
} catch (NumberFormatException e) {
      //No problem this time, but still it is good practice to care about exceptions.
      //Never trust user input :)
      //Do something! Anything to handle the exception.
}

It is important to handle this exception when trying to get integer values from split arguments or dynamically parsing something.

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