在我的Sudoku Android应用程序中，我有一个求解Sudoku难题的解决函数（一个CellField对象）。但是出于某种原因，当我克隆一个CellField对象并且我在克隆对象上调用solve方法时，solve方法解决了两个CellField对象，但我只希望它解决克隆的CellField对象而不是原始对象。有什么建议？感谢
这里我克隆了CellField对象（克隆名为temp），并且还调用了solve方法
CellField temp = null;
try {
temp = board.cf.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
int x = randInt(0,8);
int y = randInt(0,8);
while (!temp.getCell(y,x).isEditable && board.cf.getCell(y,x).getValue() == 0) {
x = randInt(0,8);
y = randInt(0,8);
}
SudokuSolver solver = new SudokuSolver();
solver.solve(temp);
这是我的求解方法和SudokuSolver类
package com.example.czhou.myapplication2;
import java.util.*;
public class SudokuSolver {
static boolean retry;
public static int randInt(ArrayList<Integer> candidates) {
int min = 0;
int max = candidates.size() - 1;
//inclusive
Random rand = new Random();
int randomNum = rand.nextInt((max - min) + 1) + min;
int result = candidates.get(randomNum);
candidates.remove(randomNum);
return result;
}
public boolean solve(CellField field) {
// write your code here
boolean isValid = true;
Set<Integer> toRemove = new HashSet<>();
int i;
int j;
for (int k = 0; k < 9; k++) {
for (int l = 0; l < 9; l++) {
field.getCell(k, l).restAlt();
if (field.getCell(k, l).alt.indexOf(field.getCell(k, l).getValue()) != -1) {
field.getCell(k, l).alt.remove(field.getCell(k, l).alt.indexOf(field.getCell(k, l).getValue()));
}
}
}
for (i = 0; i < 9; i++) {
for (j = 0; j < 9; j++) {
if (field.getCell(i,j).getValue() == 0 && field.getCell(i,j).alt.size() == 0){
field.getCell(i,j).restAlt();
}
if (field.getCell(i, j).isEditable) {
toRemove.clear();
for (int k = 0; k < 9; k++) {
toRemove.add(field.getCell(k, j).getValue());
}
toRemove.addAll(field.getSectorCandidates(i, j));
for (int k = 0; k < 9; k++) {
toRemove.add(field.getCell(i, k).getValue());
}
toRemove.removeAll(Collections.singleton(0));
field.getCell(i, j).alt.removeAll(toRemove);
if (toRemove.size() == 9 || field.getCell(i, j).alt.size() == 0) {
//When there no candidates are available
//in the current cell, come here
//toRemove.clear();
Cell cell;
boolean stop = false;
backtrack:
for (int k = j; !stop; k--) {
if (k == -1) {
if (i != 0) {
--i;
} else {
break;
}
k = 8;
}
j = k;
// Scan for previous cells have alternative candidates
cell = field.getCell(i, k);
if (cell.alt.size() > 0 && cell.isEditable) {
//bookmark the original cell
//int nextCell = k+1;
// If found a cell set value as first alternative
cell.setValue(cell.alt.get(0));
break backtrack;
} else if (cell.isEditable){
// if no alternatives set cell to 0 and continue backwards
cell.setValue(0);
}
}
} else {
field.getCell(i, j).setValue(randInt(field.getCell(i, j).alt));
}
}
}
}
// for (int m = 0; m < 9; m++) {
// for (int l = 0; l < 9; l++) {
// if (l == 0) {
// System.out.println();
// }
// System.out.print(field.getCell(m, l).getValue());
// }
// }
// System.out.println();
// System.out.println("================");
return isValid;
}
}
这是我的CellField类
package com.example.czhou.myapplication2;
import android.util.Log;
import java.io.Serializable;
import java.util.*;
import java.util.regex.Matcher;
public class CellField implements Cloneable{
protected Cell[][] field = new Cell[9][9];
public CharSequence timeElapsed = "00:00";
public CellField() {
for (int i = 0; i < 9; i++) {
for (int j = 0; j < 9; j++) {
field[i][j] = new Cell();
}
}
}
public CellField(CellField another) {
List<Cell[]> cellfield = Arrays.asList(another.field);
this.field = (Cell[][]) cellfield.toArray();
}
public CellField clone() throws CloneNotSupportedException {
return (CellField)super.clone();
}
}
答案 0 :(得分：0)
问题在于克隆方法，正如@ρяσѕρєя所说，你应该做一个深层复制。因为现在你返回相同的参考。尝试这样的事情：
public CellField clone() throws CloneNotSupportedException {
CellField clone = new CellField();
clone.field = this.field;
clone.timeElapsed = this.timeElapsed;
return clone;
}
答案 1 :(得分：0)
这是浅拷贝与深拷贝的问题。
class SomeClass implements Cloneable {
// This is the problematic field. It doesn't get cloned the way you think it is.
public Integer[] field = new Integer[5];
public SomeClass clone() throws CloneNotSupportedException {
return (SomeClass) super.clone();
}
}
public class HelloWorld {
public static void main(String []args){
SomeClass first = new SomeClass();
SomeClass second = null;
try {
second = first.clone();
} catch (CloneNotSupportedException e) {
e.printStackTrace();
}
System.out.println(first.field);
System.out.println(second.field);
// Their addresses in memory are the same
// Modifying one would modify the other
// first.field == second.field -> true
}
}
在上面的例子中，我将该类的一个实例克隆到另一个实例中，然而，它们共享相同的字段。变量类的第一个实例的字段将直接影响该类的第二个实例中的字段，因为它们都拥有对它的引用。
您可以定义复制构造函数并自行执行克隆，而不是使用Cloneable。
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