java - Now am getting incompatible error when using the if else statements

trying to run the program below but am getting an error when using the switch method

import java.util.Scanner;

/**
*
* @author kern
public class loans {

public static void main(String[] args) {

Scanner input = new Scanner(System.in);

    //variabled decleared
    double rate, payment,principal,interest,n;
    int length;
    String period;

    //input
    System.out.print("Enter the amount of money borrowed: $");

    principal = input.nextDouble();
    System.out.print("Enter the annual interest rate: ");
    interest = input.nextDouble();
    System.out.print("Enter the payment period :");
    period = input.next();
    System.out.print("Enter Loan Length:");
    length = input.nextInt();
    //process

    rate=interest/100;

    payment= principal*(rate*Math.pow((1+rate),n)/ Math.pow ((1+rate),n));

      if (period==annually) {
               n=1*length;
                System.out.prtintf(Your monthly sum is %f:,payment);{

 if (period==semiannuall) {
               n=2*length;
                System.out.prtintf(Your monthly sum is %f:,payment);{


 if (period== quarterly) {
               n=4*length;
                System.out.prtintf(Your quarterly sum is %f:,payment);{

 if (period==monthly) {
               n=12*length;
                System.out.prtintf(Your monthly sum is %f:,payment);{





}

}

Answer

String as case value are supported from java 7

See

You need to use it like

if("annually".equals(period)){
}