[!INDEX]

1. Definition ( 3points )
2. unhandled exception in caller method(file read write)
3. Exception handling in caller method with try-catch (file read write) + no file
4. Exception handling in caller method with try-catch + file.
5. difference between throws and throw.(6 points, MRSBN, DCMSC)

1. Definition ( 3points )

[!NOTE]

1. used in method declarations.
2. specify that a method might throw certain exceptions during its execution.
3. and that the calling method must handle or further propagate those exceptions.
4. It is used primarily with checked exceptions (like IOException, SQLException), which the compiler requires you to handle or declare.

2. unhandled exception in caller method(file read write)

package package2;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
public class Main1 {  
    public static void main(String[] args) {        
        ReadAndWrite r1 = new ReadAndWrite();
        r1.readFile(); // did not handle exception
    }
    class ReadAndWrite{
        void readFile() throws FileNotFoundException{ // caller is responsible
            String filePath = System.getProperty("user.home") + "/Desktop/x/abc.java";
            FileInputStream fis = new FileInputStream(filePath);
        }
        void saveFile()  throws FileNotFoundException { // caller is responsible
            String filePath1 = System.getProperty("user.home") + "/Desktop/x/abc.java";
            String text ="this is done";
            FileOutputStream fos = new FileOutputStream(filePath1);
        }
    }
}

Unhandled exception type FileNotFoundExceptionJava(16777384)

3. Exception handling in caller method with try-catch (file read write) + no file

package package2;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
public class Main1 {  
    public static void main(String[] args) {        
        ReadAndWrite r1 = new ReadAndWrite();
        try {
            r1.readFile();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.out.println("exception is handled");
        }
    }
}
    class ReadAndWrite{
        void readFile() throws FileNotFoundException{ // caller is responsible
            String filePath = System.getProperty("user.home") + "/Desktop/x/abc.java";
            FileInputStream fis = new FileInputStream(filePath);
        }
        void saveFile()  throws FileNotFoundException { // caller is responsible
            String filePath1 = System.getProperty("user.home") + "/Desktop/x/abc.java";
            String text ="this is done";
            FileOutputStream fos = new FileOutputStream(filePath1);
        }
    }

java.io.FileNotFoundException: C:\Users\rajat\Desktop\x\abc.java (The system cannot find the path specified)
        at java.base/java.io.FileInputStream.open0(Native Method)
        at java.base/java.io.FileInputStream.open(FileInputStream.java:213)
        at java.base/java.io.FileInputStream.<init>(FileInputStream.java:152)
        at java.base/java.io.FileInputStream.<init>(FileInputStream.java:106)
        at package2.ReadAndWrite.readFile(Main1.java:23)
        at package2.Main1.main(Main1.java:11)
exception is handled

4. Exception handling in caller method with try-catch +file.

package package2;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
public class Main1 {  
    public static void main(String[] args) {        
        ReadAndWrite r1 = new ReadAndWrite();
        try {
            r1.readFile();
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
            System.out.println("exception is handled");
        }
        try {
            r1.saveFile();
            System.out.println("file created");
        } catch (FileNotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }
}
    class ReadAndWrite{
        //for read file
        void readFile() throws FileNotFoundException{ // caller is responsible
//            String filePath = System.getProperty("user.home") + "/Desktop/x/abc.java";
            FileInputStream fis = new FileInputStream("d:/test.txt");
        }
        //for create file
        void saveFile()  throws FileNotFoundException { // caller is responsible
            String filePath1 = System.getProperty("user.home") + "/Desktop/x/abc.java";
            String text ="this is done";
            FileOutputStream fos = new FileOutputStream("d:/test.txt");
        }
    }

file created

5. difference between throws and throw.(6 points, MRSBN, DCMSC)

[!MA]

1. throw-MRSBN, manually run the single body machine with new idea
2. throws-DCMSC, declare, compile, multiple, signature, class

[!NOTE]

• void readFile() throws FileNotFoundException, NullPointerException, etc.

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