JAVA- IO-Copy&JAVA7自动关闭资源的try语句

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package test;import java.io.FileReader;import java.io.FileWriter;public class Copy2 {/** * 使用FileWriter FileReader拷贝文件 *  * 自动关闭资源的try语句 */public static void main(String[] args) {// try(FileWriter fw = new FileWriter("D:/qq/aa.txt");FileReader fr = new FileReader("D:/qq/bb.txt");){char[] ch =new char[1024];int len = 0;if((len = fr.read(ch))!=-1){fw.write(ch, 0, len);}}catch(Exception e){e.getStackTrace();}}}