how to throw and catch exception in java code example

Example 1: java try catch

try {
  // Code that may have error
} catch(ErrorName e){
  // Another code
}

Example 2: try block in java

try {
  //  Block of code to try
}
catch(Exception e) {
  //  Block of code to handle errors
}

Example 3: java how to throw exception

public class ThrowException{
  public static void main(String [] args) throws Exception{ 
    //throws Exception line is needed if not using try-catch block
    throw new Exception("Errmessage");
  }
}

Example 4: java throw an exception

public static void main(String[] args) {
	Scanner kb = new Scanner(System.in);
    System.out.println("Enter a number");
    try {
    	double nb1 = kb.nextDouble();
    	if(nb1<0)
        	throw new ArithmeticException();
        else System.out.println( "result : " + Math.sqrt(nb1) );
    } catch (ArithmeticException e) {
        System.out.println("You tried an impossible sqrt");
    }
}