java - method scanner input java?

Question

I'm trying to make a method that will ask the user the amount, then it checks if the amount if >0 and if it is the loop ends and if the input isnt >0 then the loop continues until proper data is entered. I can't figure out my problem..

/** Get principal amount **/
public static double getPrincipalAmount(double numb1) {
    Scanner input = new Scanner(System.in);
    do {
        System.out.print("Enter Loan Amount: ");
        double numb1 = input.nextDouble();
        double getPrincipalAmount = 0;
        if (numb1 > 0) {
            getPrincipalAmount = numb1;
        } else {    
            System.out.println("Data Error: Loan amount must be greater than zero. You entered " + numb1);
        }       
    } while (numb1 < 0);
    return getPrincipalAmount;
}

score 2 · Accepted Answer

これを試して！！！

java.util.Scanner をインポートします。

public class PrinipalDemo{



    public static void main(String args[]){

            Scanner input = new Scanner(System.in);
            double numb11;
            double getPrincipalAmount ;
           do{System.out.print("Enter Loan Amount: ");
             numb11 = input.nextDouble();
             getPrincipalAmount = 0.0;
             if(numb11 > 0)
            getPrincipalAmount = numb11;
                  else{   
                          System.out.println("Data Error: Loan amount must be greater than zero. You entered " +numb11);
                  }       
                 }while (numb11 < 0);

        System.out.println(getPrincipalAmount);

    }

}

score 0 · Accepted Answer

メソッドをパラメータ化する必要はありません。getPrincipalAmount(double numb1)
getPrincipalAmountメソッドスコープ内にある必要があります
Scanner input閉じる必要があります

これを試して

import java.util.Scanner;
public class so7 
{
public static void main(String args[])
{
    getPrincipalAmount();
}
/** Get principal amount **/
public static double getPrincipalAmount() {
    Scanner input = new Scanner(System.in);
    double getPrincipalAmount = 0;
    double numb = 0;
    do {
        System.out.print("Enter Loan Amount: ");
        numb = input.nextDouble();
        if (numb > 0) {
            getPrincipalAmount = numb;
        } else {    
            System.out.println("Data Error: Loan amount must be greater than zero. You entered " + numb);
        }       
    } while (numb < 0);
    input.close();
    return getPrincipalAmount;
}
}

score 0 · Accepted Answer

このようにしたほうがいいと思います

public static double getPrincipalAmount(double numb1) {
    numb1 = 0;
    Scanner input = new Scanner(System.in);
    do {

        System.out.print("Enter Loan Amount: ");
        numb1 = input.nextDouble();
        double getPrincipalAmount = 0;
        if (numb1 > 0) {
            getPrincipalAmount = numb1;
        } else {    
            System.out.println("Data Error: Loan amount must be greater than zero. You entered " + numb1);
        }       
    } while (numb1 < 0);
    return getPrincipalAmount;
}

score 0 · Accepted Answer

理想的には、そのような小さな問題を修正する必要があります。

public static double getPrincipalAmount() {
    final Scanner input = new Scanner(System.in);
    double getPrincipalAmount = 0;
    double numb1;
    do {
        System.out.print("Enter Loan Amount: ");
        if ((numb1 = input.nextDouble()) > 0) {
            getPrincipalAmount = numb1;
        } else {
            System.out.println("Data Error: Loan amount must be greater than zero. You entered " + numb1);
        }
    } while (numb1 < 0);
    return getPrincipalAmount;
}

score 0 · Accepted Answer

あなたのコードにはいくつかの問題があります。numb1まず、変数をパラメーターとしてメソッドに渡しますgetPrincipalAmount(double numb1)。それが、新しい宣言がDuplicate local variable numb1変数を与えている理由です。

次に、を返していますが、ループgetPrincipalAmount内でのみ初期化されます。do - whileループの外で初期化する必要があります。

java - method scanner input java?

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