private final int blanki; private final int blankj;

Question

我有这个代码：

public final class Board {
    private final int[][] blocks;
    private final int N;
    private final int blanki;
    private final int blankj;
    int i, j;
    // construct a board from an N-by-N array of blocks
   public Board(int[][] blocks)  {
        this.blocks = new int[blocks.length][blocks.length];
        for(i = 0; i < blocks.length; i++){
            for(j = 0; j < blocks.length; j++){
                this.blocks[i][j] = blocks[i][j];
                if(blocks[i][j] == 0) {
                    int f = i;
                    int c = j;
                }
            }
        }
        this.N = this.dimension();
        this.blanki = f;
        this.blankj = c;
    }
}

并得到以下错误：

文件：C:\Users\cbozanic\als4\Board.java[行：28]错误：f无法解析为变量文件：C:\Users\cbozanic\als4\Board.java[行：29]错误：c无法解析为变量文件：C:\Users\cbozanic\als4\Board.java[行：159]错误：本地变量s可能尚未初始化

我真的不明白我做错了什么！任何帮助都将不胜感激。

Answer 1

f和c在for循环的范围内定义。它们在外面看不见：

this.blocks = new int[blocks.length][blocks.length];
for(i = 0; i < blocks.length; i++){
    for(j = 0; j < blocks.length; j++){
            int f = i;
            int c = j;
    } //From this point, f and c are not defined anymore
}
}
this.N = this.dimension();
this.blanki = f; //Here, f does not exist
this.blankj = c; //Here, c does not exist

如果您想使用f和c，请在循环之前声明它们：

int f = ...
int c = ...
 for(i = 0; i < blocks.length; i++){
    for(j = 0; j < blocks.length; j++){
            f = ...;
            c = ...;
    }
}

对于消息The local variable s may not have been initialized，这意味着您声明并使用了变量而没有初始化它。例如：

int s; //For example, int s = 0; would make sense.
s++;

注意：当创建新实例但局部变量处于"未初始化"状态时，类属性采用默认值。

Answer 2

变量f在此范围内不可见：

this.blanki = f;

考虑在方法的开头添加int f = 0;。

变量c也是如此。