java - 不可变类中的编译时错误 : (final) variable might not have been initialized

Question

代码尽可能简单，但我似乎遇到了编译器错误。我错过了什么？

顺便说一句，完全删除 _name 字段只会在下一个字段上生成相同的错误。

P.S.:预计在这个问题上会有相当多的负票，感觉就像我错过了一些非常非常简单的东西。

package mkumpan.helpers;

public final class BotState
{
    private final String _name;
    private final double _x;
    private final double _y;
    private final double _energy;
    private final double _heading;
    private final double _velocity;

    public BotState(
                    String name,
                    double x,
                    double y,
                    double energy,
                    double heading,
                    double velocity
    ) {
        String _name = name;
        double _x = x;
        double _y = y;
        double _energy = energy;
        double _heading = heading;
        double _velocity = velocity;
    } // BotState.java:26: error: variable _name might not have been initialized

    public String getName() { return _name; }
    public double getX() { return _x; }
    public double getY() { return _y; }
    public double getEnergy() { return _energy; }
    public double getHeading() { return _heading; }
    public double getVelocity() { return _velocity; }
}

Answer 1

您必须初始化最终字段，但您只是在构造函数中初始化了局部变量。

改变

String _name = name;
double _x = x;
double _y = y;
double _energy = energy;
double _heading = heading;
double _velocity = velocity;

至

 this._name = name;
 this._x = x;
 this._y = y;
 this._energy = energy;
 this._heading = heading;
 this._velocity = velocity;