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23 lines
467 B
23 lines
467 B
/**
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* 圆：面积 = π * r²
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*/
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public class Circle extends Shape {
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private final double radius;
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public Circle(double radius) {
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if (radius <= 0) {
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throw new IllegalArgumentException("半径必须为正数");
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}
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this.radius = radius;
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}
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public double getRadius() {
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return radius;
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}
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@Override
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public double getArea() {
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return Math.PI * radius * radius;
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}
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}
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