[英]Java deep clone an object
将对象复制到新对象时遇到一些麻烦。
最初,我尝试了这个:
State clonedState = state;
但是后来我注意到我在“ clonedState”中所做的更改也会影响“ state”。
因此,我去搜索了,发现了关于深度克隆的知识。 有些人建议使用库,其他人建议使用序列化然后反序列化。
没有这些,没有办法做到这一点吗?
我也尝试过,结果相同:
public static State cloneState(State state){
int[][] currentBoard = state.getCurrentBoard();
int[] currentPieces = state.getCurrentPieces();
int totalPoints = state.getTotalPoints();
Piece pieceDetail = state.getPieceDetail();
int acquiredPoints = state.getAcquiredPoints();
int[] initialList = state.getInitialList();
int[][] initialBoard = state.getInitialBoard();
int parentStateID = state.getParentStateID();
int stateID = state.getStateID();
State clone = new State(parentStateID,
stateID,
currentBoard,
currentPieces,
totalPoints,
acquiredPoints,
initialList,
initialBoard,
pieceDetail);
return clone;
}
进一步阅读后,我尝试使用序列化和反序列化。 因此,我在构造函数类中添加了此方法:
public State deepCopy() throws Exception{
//Serialization of object
ByteArrayOutputStream bos = new ByteArrayOutputStream();
ObjectOutputStream out = new ObjectOutputStream(bos);
out.writeObject(this);
//De-serialization of object
ByteArrayInputStream bis = new ByteArrayInputStream(bos.toByteArray());
ObjectInputStream in = new ObjectInputStream(bis);
State clone = (State) in.readObject();
return clone;
}
在主类中,我添加了以下内容:
State clonedState = state.deepCopy();
不知何故,结果是相同的...我修改了“ clonedState”,“ state”也被修改了。
我非常感谢您的帮助!
编辑:
作为参考,以下是发生这种情况的方法:
public static void operateGreen(State state) throws Exception{
if(getNextPiece(state) == 1){ //Se a proxima peca a colorcar for um +
int pos = 0;
System.out.println("pieces in state: " + countPiecesList(state));
while (pos <= 24){//percorrer o tabuleiro
System.out.println("Position: " + pos);
State clonedState = state.deepCopy();
System.out.println("pieces in state: " + countPiecesList(state));
System.out.println("pieces in clonedState: " + countPiecesList(clonedState));
if (checkPosPiece(state, pos, -1) == true){ //se o campo estiver vazio
removePieceFromList(clonedState);
int points = 0;
nodes++;
modifyBoard(clonedState, pos, 1); //atualiza o tabuleiro
Piece pieceDetail = new Piece(1, pos); //cria nova jogada
//Verifica se fez figura
int tempPos = 6;
boolean figureFound = false;
while (tempPos <= 18 && figureFound == false){ //pesquisar se tem algum centro de figura + entre os campos 6 e 18
if (checkGreen(clonedState,tempPos)) figureFound = true;
tempPos++;
}
if (figureFound){
points = acquiredPoints(armLength(clonedState, tempPos, 0, 1, 1)*4+1); //calcula o tamanho da figura, para devolver os pontos obtidos
clearGreen(clonedState, tempPos);
}
setPieceToState(clonedState, pieceDetail);
setTotalPointsOfState(clonedState, points);
setStateID(clonedState);
setParentStateID(state, clonedState);
addState(clonedState);
}
pos++;
}
}
}
这是输出:
pieces in state: 4
Position: 0
pieces in state: 4
pieces in clonedState: 4
Position: 1
pieces in state: 3
pieces in clonedState: 3
Position: 2
pieces in state: 2
pieces in clonedState: 2
Position: 3
pieces in state: 1
pieces in clonedState: 1
Position: 4
pieces in state: 0
pieces in clonedState: 0
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: -1
at MainPC.removePieceFromList(MainPC.java:223)
at MainPC.operateGreen(MainPC.java:778)
at MainPC.setProblem(MainPC.java:945)
at MainPC.main(MainPC.java:43)
在Deepcopy方法内部,您再次使用数组和对象。 因此,状态和clonedState再次引用相同的对象。 如果不想进行序列化和反序列化,则需要为每个对象创建一个新对象并复制原始类型。
代替 :-
Piece pieceDetail = state.getPieceDetail();
你需要做:-
Piece pieceDetail = new pieceDetail();
peiceDetail.setField1(state.getPieceDetail().getfield1);
如果仅在pieceDetail内部有任何对象,则需要撤消此操作。
有关更多详细信息。 您可能会使用Java:深度克隆/复制实例的推荐解决方案
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