如何获取e.printStackTrace()的内容

package app;
import java.io.PrintWriter;
import java.io.StringWriter;
public class E {
public static void main(String[] args) {
String str = null;
try {
System.out.println(str.charAt(0));
//System.out.println(1/0);
} catch (Exception e) {
System.out.println(e.getMessage());
System.out.println(e.fillInStackTrace().getMessage());
e.printStackTrace();
StringWriter sw = new StringWriter(); 
            e.printStackTrace(new PrintWriter(sw, true)); 
            String strs = sw.toString(); 
            System.out.println("--------------------------美丽的分割线----------------------"); 
            System.out.println(strs); 
}
}

}

打印的效果如下：

null
null
java.lang.NullPointerException
at app.E.main(E.java:14)
--------------------------美丽的分割线----------------------
java.lang.NullPointerException
at app.E.main(E.java:14)