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Java7 enhanced try statement to close resources
Traditional way to close resources
import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.ObjectInputStream; import java.io.ObjectOutputStream; class Student implements Serializable { private String name; public Student(String name) { this.name = name; } } public class test2 { public static void main(String[] args) throws Exception { Student s = new Student("WJY"); Student s2 = null; ObjectOutputStream oos = null; ObjectInputStream ois = null; try { //创建对象输出流 oos = new ObjectOutputStream(new FileOutputStream("b.bin")); //创建对象输入流 ois = new ObjectInputStream(new FileInputStream("b.bin")); //序列化java对象 oos.writeObject(s); oos.flush(); //反序列化java对象 s2 = (Student) ois.readObject(); } finally { //使用finally块回收资源 if (oos != null) { try { oos.close(); } catch (Exception ex) { ex.printStackTrace(); } } if (ois != null) { try { ois.close(); } catch (Exception ex) { ex.printStackTrace(); } } } } }
Use the finally block to close physical resources to ensure that the shutdown operation will always be executed.
Before closing each resource, first ensure that the reference reference to the resource variable is not null.
Use a separate try...catch block for each physical resource to close the resource to ensure that exceptions caused when closing the resource will not affect the closing of other resources.
The above method causes the finally block code to be very bloated and the readability of the program is reduced.
java7 enhanced try statement to close resources
In order to solve the problem of uploading in the traditional way Question, Java7added a try statement that automatically closes resources. It allows a pair of parentheses to be followed by the try keyword, in which one or more resources can be declared and initialized. The resources here refer to those resources that must be explicitly closed when the program ends (database connections, network connections, etc.) , the try statement will automatically close these resources at the end of the statement.
public class test2 { public static void main(String[] args) throws Exception { Student s = new Student("WJY"); Student s2 = null; try (//创建对象输出流 ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("b.bin")); //创建对象输入流 ObjectInputStream ois = new ObjectInputStream(new FileInputStream("b.bin")); ) { //序列化java对象 oos.writeObject(s); oos.flush(); //反序列化java对象 s2 = (Student) ois.readObject(); } } }
Note:
The resource that is automatically closed must implement Closeable or AutoCloseableThe closed resource must be placed in Declared and initialized in parentheses after the try statement. If the program has a try statement that needs to automatically close resources, it can include multiple catch blocks and a finally block. Java7 has rewritten almost all "resource classes" (including various classes of file IO, JDBCThe above is the detailed content of A brief introduction to Java7 enhanced try statement to close resources. For more information, please follow other related articles on the PHP Chinese website!