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anarresian/VisibilityTest.java

Created June 15, 2016 09:41
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VisibilityTest.java
package tests;
import java.lang.reflect.Field;
public class VisibilityTest {
public static void main(String[] args){
try {
Class type = Class.forName("java.io.BufferedWriter");
Field defaultCharBufferSize = type.getDeclaredField("defaultCharBufferSize");
try {
defaultCharBufferSize.setInt(defaultCharBufferSize, 10);
} catch (IllegalAccessException e) {
// we can't change field value directly?
System.out.println("Direct change failed.");
System.err.println(e.getMessage());
}
defaultCharBufferSize.setAccessible(true);
defaultCharBufferSize.setInt(defaultCharBufferSize, 10);
if (defaultCharBufferSize.getInt(defaultCharBufferSize) == 10)
System.out.println("Change successful after setAccessible()");
} catch (ClassNotFoundException | NoSuchFieldException | SecurityException | IllegalArgumentException | IllegalAccessException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
/*
Direct change failed.
Class tests.VisibilityTest can not access a member of class java.io.BufferedWriter with modifiers "private static"
Change is successful after setAccessible().
*/
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