Question

我有这段代码：

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;
    }

}

并获得以下错误：

文件：C：\ Users \ cbozanic \ algs4 \ Board.java [line：28] 错误：f无法解析为变量文件：C：\ Users \ cbozanic \ algs4 \ Board.java [line：29] 错误：c无法解析为变量文件：C：\ Users \ cbozanic \ algs4 \ Board.java [line：159] 错误：局部变量s可能尚未初始化

我真的不知道我做错了什么！任何帮助将不胜感激。

Answer 1

f和c在for循环的范围内定义。它们在外面是不可见的：

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

如果你想使用f和c，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该变量而未初始化它。例如：

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

注意：类属性在创建新实例时采用默认值，但局部变量保持“未初始化”状态。

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;。

同样适用于变量c。

私人决赛int blanki; private final int blankj;

2 个答案: