从另一个类访问int[]时出现问题
从另一个类访问int[]时出现问题
提问于 2019-06-19 03:02:17
我尝试运行以下代码，但由于某些原因，从类IntelligentPlayer访问field.playField时总是得到一个NullPointerException
public class IntelligentPlayer extends RealPlayer {
private int[][] winning = new int[][]{{0, 1, 2}, {3, 4, 5}, {6, 7, 8}, {0, 3, 6}, {1, 4, 7}, {2, 5, 8}, {0, 4, 8}, {2, 4, 6}};
protected Field field;
protected int self;
public int move(int move) {
for (int[] possibility:winning) {
return fieldCount(possibility, 3)[1];
}
}
private int[] fieldCount(int[] test, int len) {
System.out.println("" + test[0] + test[1] + test[2]);
System.out.println(field.playField[2]);
int[] temp = new int[]{0, 0, 0};
for (int i = 0; i < len; i++) {
if (field.playField[test[i]]==self) {
temp[0]+=1;
}else if (field.playField[test[i]]==(self*-1)) {
temp[1]+=1;
} else {
temp[2]+=1;
}
}
return temp;
}
}public class Field {
int[][] winning = new int[][]{{0, 1, 2}, {3, 4, 5}, {6, 7, 8}, {0, 3, 6}, {1, 4, 7}, {2, 5, 8}, {0, 4, 8}, {2, 4, 6}};
public int[] playField = new int[9];
protected char[] symbols = new char[]{'O', ' ', 'X'};
private int turn;
private RealPlayer player1;
private RealPlayer player2;
public Field(RealPlayer pl1, RealPlayer pl2) {
this.player1 = pl1;
this.player2 = pl2;
this.player1.field = this;
this.player2.field = this;
this.player1.self = -1;
this.player2.self = 1;
this.playField = new int[]{0, 0, 0, 0, 0, 0, 0, 0, 0};
}
}编辑:测试代码为：
Field f = new Field(new RealPlayer(), new IntelligentPlayer(), -1);
f.move(2);
System.out.println(f.toString());
f.move(2);
System.out.println(f.toString());
f.move(0);我期望fieldCount返回一个整型数组，但得到的结果是：
java.lang.NullPointerException
at TicTacToe.IntelligentPlayer.fieldCount(IntelligentPlayer.java:60)
at TicTacToe.IntelligentPlayer.move(IntelligentPlayer.java:24)
at TicTacToe.Field.move(Field.java:50)回答 1
Stack Overflow用户
回答已采纳
发布于 2019-06-19 03:30:53
从IntelligentPlayer类中删除protected Field field;。这将允许该类访问父类中定义的field字段(这是Field构造函数设置的内容)。
更好的是，在RealPlayer中定义一个设置器并使用它，而不是直接为变量赋值：
public void setField(Field field) {
this.field = field;
} public Field(RealPlayer pl1, RealPlayer pl2) {
this.player1 = pl1;
this.player2 = pl2;
this.player1.setField(this);
this.player2.setField(this);
this.player1.self = -1;
this.player2.self = 1;
this.playField = new int[]{0, 0, 0, 0, 0, 0, 0, 0, 0};
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/56655487
复制相关文章
相似问题
腾讯云开发者
