if 문이 while 루프 내에서 작동하지 않을 경우

Question

이것은 내 첫 번째 게시물이므로 오해가 생겨서 유감스럽게 생각합니다.이 계산기를 C++로 작성 했으므로 훌륭하게 작동하여 java로 만들었습니다. 나는이 프로그램을 실행하면 그것은 나에게 오류지만을 제공하지 내 내 while 루프 내부의 문은 당신이 원하는 것을하지 않는 ==을 사용하여 Java에서 문자열을 비교

import java.util.Scanner; 

public class ohmlaw 
{ 
    public static void main(String args[]) 
{ 
    float current; 
    float resistance; 
    float voltage; 
    String calchoice = new String(); 
    Scanner cc = new Scanner(System.in); 
    System.out.println("OHMCAL, OHM'S LAW CALCULATOR BY RASHAAD BRYAN"); 
    System.out.println(); 
    System.out.println(); 
    System.out.println(); 
    System.out.println("Instructions"); 
    System.out.println("If you want to calculate the voltage type voltage"); 
    System.out.println("If you want to calculate the current type current"); 
    System.out.println("If you want to calculate the resistance type resistance"); 
    System.out.println("If you want to stop the program type stop"); 
    System.out.println(); 
    System.out.println(); 
    System.out.println(); 
    System.out.print("Please enter calculation choice "); 
    calchoice = cc.nextLine(); 
    System.out.println(); 
    while (calchoice != "stop") 
    { 
     if (calchoice == "current") 
     { 
      System.out.print("Please enter voltage (V) "); 
      voltage = cc.nextFloat(); 
      System.out.println(); 
      System.out.print("Please enter resistance() "); 
      resistance = cc.nextFloat(); 
      System.out.println(); 
      current = voltage/resistance; 
      System.out.println("The current is = " + current + "A"); 
      System.out.println(); 
     } 
     if (calchoice == "voltage") 
     { 
      System.out.print("Please enter current (V) "); 
      current = cc.nextFloat(); 
      System.out.println(); 
      System.out.print("Please enter resistance() "); 
      resistance = cc.nextFloat(); 
      System.out.println(); 
      voltage = current * resistance; 
      System.out.println("The voltage is = " + voltage + "V"); 
      System.out.println(); 
     } 
     if (calchoice == "resistance") 
     { 
      System.out.print("Please enter Voltage (V) "); 
      voltage = cc.nextFloat(); 
      System.out.println(); 
      System.out.print("Please enter current (I) "); 
      current = cc.nextFloat(); 
      System.out.println(); 
      resistance = voltage/current; 
      System.out.println("The resistance is = " + resistance + ""); 
      System.out.println(); 
     } 
     System.out.print("Please enter calculation choice "); 
     calchoice = cc.nextLine(); 
     System.out.println(); 
     System.out.println(); 
    } 
    System.out.println("Thank you for using OHMCAL, have a nice day :D"); 
    System.out.println(); 
} 

}

Answer 1

작동하지 않는 경우. 대신 calchoice.equals(...)을 사용하십시오.

Answer 2

단지 == 사용하여 비교하지 마십시오 .equals() 대신