Java 是否总是需要在方法内部编写try-catch(),static void main()是否是方法,static void main()是否是方法?
为什么不在一个方法内的尝试捕获会起作用Java 是否总是需要在方法内部编写try-catch(),static void main()是否是方法,static void main()是否是方法?,java,serialization,try-catch,Java,Serialization,Try Catch,为什么不在一个方法内的尝试捕获会起作用 package ro.ase.acs.main; import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.io.ObjectInputStream; import java.
package ro.ase.acs.main;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import ro.ase.acs.classes.Addition;
import ro.ase.acs.classes.Robot;
import ro.ase.acs.interfaces.BinaryOperation;
import ro.ase.acs.interfaces.DisplayService;
public class Main {
public static void main(String[] args) {
Robot robot = new Robot();
robot.setName("Lego Mindstorms");
robot.setAutonomy(2);
robot.setProductionYear(2015);
try(FileOutputStream fos = new FileOutputStream("robot.bin");
DataOutputStream data = new DataOutputStream(fos)) {//baga in fisier datele setate mai sus;
data.writeUTF(robot.getName());
data.writeFloat(robot.getAutonomy());
data.writeInt(robot.getProductionYear());
} catch(IOException e) {
e.printStackTrace();
}
Robot robot2 = new Robot();
try(FileInputStream fis = new FileInputStream("robot.bin");//se citesc datele din fisier;se creeaza un al 2-lea obiect cu datele pe care le-am bagat anterior in fisier;
DataInputStream data = new DataInputStream(fis)) {
robot2.setName(data.readUTF());
robot2.setAutonomy(data.readFloat());
robot2.setProductionYear(data.readInt());
} catch(IOException e) {
e.printStackTrace();
}
System.out.println(robot2);
try(FileOutputStream fos = new FileOutputStream("robot.dat");
ObjectOutputStream oos = new ObjectOutputStream(fos)) {//ia toate datele ,atributele gasite -n obiectul dat,anterior, cand le-am setat la inceputul programului
//le scrie byte cu byte in fisier
oos.writeObject(robot);
} catch(IOException e) {
e.printStackTrace();
}
Robot robot3 = new Robot();
try(FileInputStream fis = new FileInputStream("robot.dat");//se baga datele, luate anterior, in robot3;
ObjectInputStream ois = new ObjectInputStream(fis)) {
robot3 = (Robot)ois.readObject();
} catch(IOException | ClassNotFoundException e) {
e.printStackTrace();
}
System.out.println(robot3);
System.out.println(new Robot());
BinaryOperation op = new Addition();
op = new BinaryOperation() {
@Override
public double operation(int x, int y) {
return x - y;
}
};
op = (int a, int b) -> a * b;
op = (a, b) -> a / b;
op = (a, b) -> { return Math.pow(a, b); };
double result = op.operation(2, 3);
System.out.println(result);
DisplayService ds = (m) -> System.out.println(m);
ds = m -> { System.out.print("Message: "); System.out.println(m);};
ds.display("Hello from the Lambda expression");
}
}
这是我的老师写的代码,我读到try-catch()只在方法中起作用,但在上面的代码中,它不在方法中起作用。在try-catch之前声明一个新对象并编写try而不将其包含在方法中是否足够
是的,static void main()是一个方法,这就是为什么我们可以在static void main()中编写try-catch语句而不会出现错误的原因。
public static void main(String[]args){…}
是一个方法,try-catch块在这个主方法中执行
一般来说,要回答您的问题:您可以在方法中编写try-catch块,也可以使用静态块(将在main方法之前执行):
但是,您不能编写以下内容:
class ClassName {
//try-catch here
}
不在方法内部是什么意思?在上面的代码中,它位于main方法中
class ClassName {
//try-catch here
}