why chrome driver is not working in @Before?

I have a simple code

  public class PageAvailable {
            @Test
            public void test() {
                System.setProperty("webdriver.chrome.driver", "C:/Users/JARs/chromedriver_win32/chromedriver.exe");
                WebDriver driver = new ChromeDriver();
                driver.get("https://....net");
                System.out.println(driver.getTitle());
                driver.close();
            }}

above code is working fine
Now i want this code in more structure way

public class PageAvailable {
WebDriver driver = new ChromeDriver();
@Before
public void be(){
    System.setProperty("webdriver.chrome.driver", "C:/Users/JARs/chromedriver_win32/chromedriver.exe");
    driver.get("....net");

}
@Test
public void test() {
    driver.get("https://...net");
    System.out.println(driver.getTitle());
}
@After
public void af(){
driver.close();
}}  

I am getting following error after executing above code

java.lang.IllegalStateException: The path to the driver executable must be set by the webdriver.chrome.driver system property; for more information, see http://ift.tt/1MNpI1r. The latest version can be downloaded from http://ift.tt/1hV5c2G at com.google.common.base.Preconditions.checkState(Preconditions.java:199) at org.openqa.selenium.remote.service.DriverService.findExecutable(DriverService.java:109) at org.openqa.selenium.chrome.ChromeDriverService.access$000(ChromeDriverService.java:32) at org.openqa.selenium.chrome.ChromeDriverService$Builder.findDefaultExecutable(ChromeDriverService.java:137) at org.openqa.selenium.remote.service.DriverService$Builder.build(DriverService.java:296) at org.openqa.selenium.chrome.ChromeDriverService.createDefaultService(ChromeDriverService.java:88) at org.openqa.selenium.chrome.ChromeDriver.(ChromeDriver.java:116) at sample.PageAvailable.(PageAvailable.java:12) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source) at java.lang.reflect.Constructor.newInstance(Unknown Source) at org.junit.runners.BlockJUnit4ClassRunner.createTest(BlockJUnit4ClassRunner.java:217) at org.junit.runners.BlockJUnit4ClassRunner$1.runReflectiveCall(BlockJUnit4ClassRunner.java:266) at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12) at org.junit.runners.BlockJUnit4ClassRunner.methodBlock(BlockJUnit4ClassRunner.java:263) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78) at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57) at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290) at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71) at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288) at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58) at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

I think something is missing from my side.
Thanks in advance for the help.