Java計算器開關不工作

Question

我可以輸入2個數字，但是當我輸入「wahl」（開關）的整數時，結果是錯誤的。

import java.util.Scanner; 


public class taschenrechner { 

    public static void main(String[] args) { 

     Scanner s = new Scanner(System.in); 

     System.out.println("Bitte erste Zahl eingeben:"); 
     int a = s.nextInt(); 
     System.out.println("Bitte zweite Zahl eingeben:"); 
     int b = s.nextInt(); 

     System.out.println("1.+ \n 2.- \n 3.* \n 4. /"); 
     int wahl = s.nextInt(); 

     switch(wahl){ 
      case 1: 
       addieren(a,b); 
       break; 
      case 2: 
       subtrahieren(a,b); 
       break; 
      case 3: 
       multiplizieren(a,b); 
       break; 
      case 4: 
       dividieren(a,b); 
       break; 
      } 
     System.out.println("Bye Bye World"); 
    } 

    private static int addieren(int a, int b){ 
     int c = a + b; 
     return c; 
    } 

    private static int subtrahieren(int a, int b){ 
     int c = a - b; 
     return c; 
    } 

    private static int multiplizieren(int a, int b){ 
     int c = a * b; 
     return c; 
    } 

    private static int dividieren(int a , int b){ 
     int c = a/b; 
     return c; 

    } 

} 

也許某種方法泄漏？

我想用方法和返回函數來練習一下java。

Answer 1

你的方法返回int，但你似乎並沒有使用結果，而是將它們改爲void。在switch案件

嘗試測試的東西，如：

System.out.println(multiplizieren(a,b)); 

這將打印結果sdtout。

另請注意，按照Java和SO慣例，代碼都應該在English（儘管在這種情況下很明顯）。

Answer 2

如果你想看到的結果，使用來自於一個新的變量的方法main返回值（比方說，result），或者打印出來使用System.out.println()或類似的東西在裏面方法的結果。例如像這樣：

int result = 0; 
    case 1: 
     result = addieren(a,b); 
     break; 
    case 2: 
     result = subtrahieren(a,b); 
     break; 
    case 3: 
     result = multiplizieren(a,b); 
     break; 
    case 4: 
     result = dividieren(a,b); 
     break; 
    } 

    System.out.println("Result = " + result); 

Answer 3

你剛剛返回的結果...... 你要打印結果，也

int result = 0 
    switch(wahl){ 
      case 1: 
       result = addieren(a,b); 
       break; 
      case 2: 
       result = subtrahieren(a,b); 
       break; 
      case 3: 
       result = multiplizieren(a,b); 
       break; 
      case 4: 
       result = dividieren(a,b); 
       break; 
      } 

System.out.println(result) 

Answer 4

如果要返回的結果，那麼你應該把它放在一些valriable或者可以soprintln 像直接顯示由...

switch(wahl){ 
case 1: 
    system.out.println(addieren(a,b)); 
or 
int result = addieren(a,b) 
system.out.println(result); 

Answer 5

int result = 0 
switch(wahl){ 
     case 1: 
      result = addieren(a,b); 
      break; 
     case 2: 
      result = subtrahieren(a,b); 
      break; 
     case 3: 
      result = multiplizieren(a,b); 
      break; 
     case 4: 
      result = dividieren(a,b); 
      break; 
     } 
//Print the result using a syso 
System.out.println(result) 

Answer 6

OK這裏有幾個三分球，可能是有用的：

import java.util.Scanner; 

// Class names typically start with a capital letter, good practice to get accustomed to 
public class Taschenrechner { 

public static void main(String[] args) { 

Scanner s = new Scanner(System.in); 

System.out.println("Bitte erste Zahl eingeben:"); 
int a = s.nextInt(); 
System.out.println("Bitte zweite Zahl eingeben:"); 
int b = s.nextInt(); 

System.out.println("1.+ \n 2.- \n 3.* \n 4. /"); 
int wahl = s.nextInt(); 

switch(wahl){ 
case 1: 
    addieren(a,b); // <- nothing happens to the result!! 
    break; 
case 2: 
    subtrahieren(a,b); // <- nothing happens to the result!! 
    break; 
case 3: 
    multiplizieren(a,b); // <- nothing happens to the result!! 
    break; 
case 4: 
    dividieren(a,b); // <- nothing happens to the result!! 
    break; 
default: // <- always good to have a default in a switch 
    // warn user that invalid option is entered 
} 

System.out.println("Bye Bye World"); 
} 

// dont need the integer "c" as you never use it locally. 
private static int addieren(int a, int b){ 
    retrun a + b; 
} 

private static int subtrahieren(int a, int b){ 
    return a - b; 
} 

private static int multiplizieren(int a, int b){ 
    return a * b; 
} 

private static int dividieren(int a , int b){ 
    return a/b; 
} 
} 

我想你做的4種操作方法靜態的，因爲你把它在主，編譯器會抱怨靜態參考？如果是這樣，請仔細閱讀一下static的含義;並考慮通過創建計算器的一個實例：

---

Taschenrechner t = new Taschenrechner(); 
t.addieren(a,b); //the methods don't need to be static anymore :) 

---

：

1. 提供一個構造函數方法和
2. 在main像創建它的一個實例

   希望它有幫助

Answer 7

您可以使用此示例

package com.alindal.calc; 
import java.util.Scanner; 

public class Calc { 

    public static void main(String[] args) { 
     System.out.println("Select an option : \n 1:Addition 2:Subtraction 3:Multiplication 4: Division"); 
     // TODO Auto-generated method stub 
Scanner read=new Scanner(System.in); 
int x=read.nextInt(); 
    switch(x) 
    { 
    case 1: 
     add(); 
     break; 
    case 2: 
     sub(); 
     break; 
    case 3: 
     multi(); 
     break; 
    case 4: 
     div(); 
     break; 
     default: 
      System.out.println("Invalid choice"); 
    } 

    } 
    public static void add() 
    { 
     Scanner read=new Scanner(System.in); 
     System.out.println("Enter the values a and b"); 
     int a=read.nextInt(); 
     int b=read.nextInt(); 
    int c=a+b; 
    System.out.println("The sum is "+c); 
    } 
    public static void sub() 
    { 
     System.out.println("Enter the values a and b"); 
     Scanner read=new Scanner(System.in); 
     int a=read.nextInt(); 
     int b=read.nextInt(); 
    int c=a-b; 
    System.out.println("The difference is "+c); 
    } 
    public static void multi() 
    { 
     System.out.println("Enter the values a and b"); 
     Scanner read=new Scanner(System.in); 
     int a=read.nextInt(); 
     int b=read.nextInt(); 
    int c=a*b; 
    System.out.println("The product is "+c); 
    } 
    public static void div() 
    { 
     System.out.println("Enter the values a and b"); 
     Scanner read=new Scanner(System.in); 
     int a=read.nextInt(); 
     int b=read.nextInt(); 
    int c=a/b; 
    System.out.println("The division is "+c); 
    } 

}