converting-string-to-int-in-java

Author: giantray

README.md

@@ -17,7 +17,7 @@ stackoverflow-Java-top-qa
 * [如何判断数组Array是否包含指定的值？](https://github.com/giantray/stackoverflow-java-top-qa/blob/master/contents/in-java-whats-the-difference-between-public-default-protected-and-private.md)
 * [重写（Override）equlas和hashCode方法时应考虑的问题](https://github.com/giantray/stackoverflow-java-top-qa/blob/master/contents/what-issues-should-be-considered-when-overriding-equals-and-hashcode-in-java.md)
 * [从一个多层嵌套循环中直接跳出](https://github.com/giantray/stackoverflow-java-top-qa/blob/master/contents/breaking-out-of-nested-loops-in-java.md)
-
+* [如何将String转换为Int](https://github.com/giantray/stackoverflow-java-top-qa/blob/master/contents/converting-string-to-int-in-java.md)
 
 > 编程技巧
 
@@ -44,7 +44,6 @@ stackoverflow-Java-top-qa
 - [Generating random integers in a range with Java](http://stackoverflow.com/questions/363681/generating-random-integers-in-a-range-with-java)
 - [Why is printing “B” dramatically slower than printing “#”?](http://stackoverflow.com/questions/21947452/why-is-printing-b-dramatically-slower-than-printing)
 - [What is a serialVersionUID and why should I use it?](http://stackoverflow.com/questions/285793/what-is-a-serialversionuid-and-why-should-i-use-it)
-- [Converting String to int in Java?](http://stackoverflow.com/questions/5585779/converting-string-to-int-in-java)
 - [Is there a unique Android device ID?](http://stackoverflow.com/questions/2785485/is-there-a-unique-android-device-id)
 - [How to test a class that has private methods, fields or inner classes](http://stackoverflow.com/questions/34571/how-to-test-a-class-that-has-private-methods-fields-or-inner-classes)
 - [Why does this code using random strings print “hello world”?](http://stackoverflow.com/questions/15182496/why-does-this-code-using-random-strings-print-hello-world)

contents/converting-string-to-int-in-java.md

@@ -0,0 +1,37 @@
+##如何将String转换为Int
+
+有两种方式
+
+```java
+Integer x = Integer.valueOf(str);
+// or
+int y = Integer.parseInt(str);
+```
+这两种方式有一点点不同：
+- `valueOf`返回的是`java.lang.Integer`的实例
+- `parseInt`返回的是基本数据类型 int
+
+`Short.valueOf/parseShort`,`Long.valueOf/parseLong`等也是有类似差别。
+
+另外还需注意的是，在做int类型转换时，可能会抛出NumberFormatException，因此要做好异常捕获
+```java
+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.
+}
+```
+
+stackoverflow链接：http://stackoverflow.com/questions/5585779/converting-string-to-int-in-java