Question

我正在处理此代码以接收目标String并搜索目标的链接列表并删除它的所有实例。我觉得我有大部分逻辑，但我得到一个NullPointerException并需要一些帮助。这是代码：

public abstract class Viewer {
    private String username;
    private int level;
    private int exp;
    private int points;
    private int intermediatePoints;
    private boolean isMod;
    private boolean isPreviousWinner;
    private boolean enteredRaffle;

    public Viewer(String username){
        this.username = username;
        this.level = 0;
        this.exp = 0;
        this.points = 0;
        this.intermediatePoints = 0;
        this.isMod = false;
        this.isPreviousWinner = false;
        this.enteredRaffle = false;
    }

    public Viewer(String username, int level, int exp, int points, int intermediatePoints, 
            boolean isMod, boolean isPreviousWinner, boolean enteredRaffle){
        this.username = username;
        this.level = level;
        this.exp = exp;
        this.points = points;
        this.intermediatePoints = intermediatePoints;
        this.isMod = isMod;
        this.isPreviousWinner = isPreviousWinner;
        this.enteredRaffle = enteredRaffle;
    }

public String setViewerString(){
        String viewerDataString = String.format("%s;%d;%d;%d;%d;%b;%b;%b;", 
                username, level, exp, points, intermediatePoints, isMod, isPreviousWinner, enteredRaffle);
        return viewerDataString;
    }

    public void parseViewerDataString(){

    }
}

}

Answer 1

您必须使用非空引用初始化当前和上一页！...

current = head; prev = head;

但是head在构造函数中设置为null ...

current.getNext();

因为当前未初始化，这是一个空指针异常

JAVA链表删除节点NullPointerException

1 个答案: