Java 三元运算符 (? :) doesn't work; second or third operand return boolean

Question

有人可以告诉我为什么三元运算符的使用不正确吗？操作数 2 和 3 返回一个 boolean 值。

public class Something {
...
private static final double REFERENCE_FRAME_MID_X = 0;
private static final double REFERENCE_FRAME_MID_Y = 0;

private boolean findInsideOrOutsideGeneralEllipse(Point2D destCirclePos) {
    List<Boolean> returnValue = new ArrayList<>();
    Point2D referenceFrameCenter = new Point2D.Double(REFERENCE_FRAME_MID_X, REFERENCE_FRAME_MID_Y);
    Ellipse2D insideAreaEllipse2D = getEllipse2D(referenceFrameCenter.getX(), referenceFrameCenter.getY(),
                                                    destCirclePos.distance(referenceFrameCenter));

    // doesn't work
    insideAreaEllipse2D.contains(destCirclePos) ? returnValue.add(true) : returnValue.add(false);

    // works
    if (insideAreaEllipse2D.contains(destCirclePos)) {
        returnValue.add(true);
    } else {
        returnValue.add(false);
    }
}
...
}

Answer 1

Java 三元运算条件的用法应该如下所示

result = testCondition ? value1 : value2

这是java语言规范。

Equality, Relational, and Conditional Operators

In the following example, this operator should be read as: "If someCondition is true, assign the value of value1 to result. Otherwise, assign the value of value2 to result