java - 将参数传递给方法并创建深拷贝

Question

public class ScoreCard {  strong text  
     private double[] scores;
/** 
 * @param val
 * @param low
 * @param high
 * @return low if val < low, 
 * high if val > high, 
 * val if val is between low and high
 */

private double constrain(double val, int low, int high) {
    if (val < low)
        return low;
    if (val > high)
        return high;
    else
        return val;
    }

/**
 * DEEP copy m into scores with each item contrained between 0 and 100.
 * use method {@link this#constrain(double, int, int)}.
 * For example, if s = {-15.2, 67.4, 126.8}, scores should become
 * {0, 67.4, 100}, AND scores should be a DEEP copy of s.
 * @param s (assume s is not null)
 */

public void setMarks(double[] s) {
     for(int i = 0; i < s.length; i++) {
        if (s[i] < 0 || s[i] > 100)
            constrain(s[i], 0, 100);
            this.scores[i] = s[i];
    }
}

我已经在这部分代码上停留了一段时间了。正如 Javadoc 所述，我无法将“constrain”的参数调用到“setMarks”以设置 < 0 到 0 和 scores > 100 到 100 的分数。我也不认为我的代码正确地创建了深拷贝将“s”正确地转换为“scores”。

任何朝着正确方向的插入将不胜感激。

Answer 1

问题是您只是将 s 的值分配给 scores，而没有考虑 constraints 的结果。下面的代码应该可以做到这一点。

public void setMarks(double[] s) {
     for(int i = 0; i < s.length; i++) {
        if (s[i] < 0 || s[i] > 100)
            this.scores[i] = constrain(s[i], 0, 100); // <- this solves!
        else
            this.scores[i] = s[i];
    }
}

作为替代方案，更简单、更清洁:

private double constrain(double val, int low, int high) {
    if (val < low)
        return low;
    if (val > high)
        return high;
    return val; // <- notice here
}

public void setMarks(double[] s) {
     for(int i = 0; i < s.length; i++) {
           this.scores[i] =  constrain(s[i], 0, 100); // <- notice here
    }
}