我應該檢查該值，如果不是該值，我不會更新該值。如果輸入有效，那么我將返回它。最小可重現示例：public class Student { private int studentId; private String name; private double grade; private double multiplier; public double getMultiplier() { return multiplier; } /** * The setter for the multiplier must check that the value is either 1.08 * * 1.06 or 1.08 or 1.06 * * If not, then do not update the value * * @param multiplier * @return if the input was valid */ public boolean setMultiplier(double multiplier) { if( multiplier == 1.08 * 1.06 || multiplier == 1.08 || multiplier == 1.06 ) { } return multiplier; } ...}
4 回答
斯蒂芬大帝
TA貢獻1827條經驗 獲得超8個贊
public void setMultiplier(double multiplier) { // method head
if (multiplier == 1.08 * 1.06 || multiplier == 1.08 || multiplier == 1.06) {
this.multiplier = multiplier; // here the field variable is overwritten
}
throw new IllegalArgumentException("exception message");
}
你忘了寫你的類的字段變量。
setter 應該覆蓋字段變量。setter 應該覆蓋字段變量。他沒有返回任何內容，因此在方法頭中返回 void 而不是 boolean 。如果參數錯誤，拋出異常（盡可能有意義）。
提示：我不會將 1.06 或 1.08 等常量分布在代碼中的任何位置。您可以將其定義如下：
public class student {
private static final double MEANINGFUL_NAME_0 = 1.06;
private static final double MEANINGFUL_NAME_1 = 1.08;
// other code below
}
優點：如有必要，您只需在一處更改常量。您錯過并寫 1.07 而不是 1.06 的可能性較低。
蠱毒傳說
TA貢獻1895條經驗 獲得超3個贊
可能是常量的用例：
private static final double ONE_DOT_ZERO_SIX = 1.06f;
private static final double ONE_DOT_ZERO_EIGHT = 1.08f;
/**
* Just to know if it is valid
*/
public boolean setMultiplier(double multiplier) {
return (multiplier == ONE_DOT_ZERO_SIX || multiplier == ONE_DOT_ZERO_EIGHT
|| multiplier == (ONE_DOT_ZERO_SIX * ONE_DOT_ZERO_EIGHT));
}
/**
* Return the multiplier if it is valid, otherwise 1
*/
public double setMultiplier(double multiplier) {
if (multiplier == ONE_DOT_ZERO_SIX || multiplier == ONE_DOT_ZERO_EIGHT
|| multiplier == (ONE_DOT_ZERO_SIX * ONE_DOT_ZERO_EIGHT)) {
return multiplier;
} else {
// return any invalid multiplier, this one doesn't change values at least
return 1;
}
}
/**
* Set the correct multiplier or a substitute
*/
public void setMultiplier(double multiplier) {
if (multiplier == ONE_DOT_ZERO_SIX || multiplier == ONE_DOT_ZERO_EIGHT
|| multiplier == (ONE_DOT_ZERO_SIX * ONE_DOT_ZERO_EIGHT)) {
this.multiplier = multiplier;
} else {
// return any invalid multiplier, this one doesn't change values at least
this.multiplier = 1;
}
}
當年話下
TA貢獻1890條經驗 獲得超9個贊
Asetter應該更新一個值，并且不返回值（getter的角色），因此它的返回類型應該是void而不是boolean
public void setMultiplier(double multiplier) {
if( multiplier == 1.08 * 1.06 || multiplier == 1.08 || multiplier == 1.06 ) {
this.multiplier = multiplier;
}
}
阿晨1998
TA貢獻2037條經驗 獲得超6個贊
我認為您只是忘記實際設置新值。
因此，如果你這樣做，它應該可以工作：
public void setMultiplier(double multiplier) {
if( multiplier == 1.08 * 1.06 || multiplier == 1.08 || multiplier == 1.06 ) {
this.multiplier = multiplier;
}
}
此外，setter 通常void不是布爾值，并且沒有返回值。
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