[英]StackOverFlowError when looping through options
I'm working on an exercise and I'm running into something. 我正在练习,却遇到了一些问题。 The following code gives me a stackoverflow error, but I have no idea why because my code should stop.
以下代码给了我一个stackoverflow错误,但是我不知道为什么,因为我的代码应该停止。
class Options {
private int amount;
private ArrayList<Integer> pieces;
public void execute() {
pieces = new ArrayList<Integer>();
pieces.add(5);
pieces.add(2);
pieces.add(3);
amount = pieces.size();
combinations(new StringBuilder());
}
public void combinations(StringBuilder current) {
if(current.length() == pieces.size()) {
System.out.println(current.toString());
return;
}
for(int i = 0; i < amount; i++) {
current.append(pieces.get(i));
combinations(current);
}
}
}
It only prints the first output (555). 它仅打印第一个输出(555)。
Thanks. 谢谢。
Add a return to end your recursion 添加退货以结束递归
public void combinations(StringBuilder current) {
if(current.length() == pieces.size()) {
System.out.println(current.toString());
return; // <-- like so.
}
for(int i = 0; i < amount; i++) {
current.append(pieces.get(i));
combinations(current);
}
}
or put the loop in an else
like 或将循环放在
else
类似
public void combinations(StringBuilder current) {
if(current.length() == pieces.size()) {
System.out.println(current.toString());
} else {
for(int i = 0; i < amount; i++) {
current.append(pieces.get(i));
combinations(current);
}
}
}
Edit 编辑
static class Options {
private List<Integer> pieces;
public void execute() {
pieces = new ArrayList<>();
pieces.add(5);
pieces.add(2);
pieces.add(3);
combinations(new StringBuilder());
}
public void combinations(StringBuilder current) {
if (current.length() == pieces.size()) {
System.out.println(current.toString());
} else {
for (int i = current.length(); i < pieces.size(); i++) {
current.append(pieces.get(i));
combinations(current);
}
}
}
}
public static void main(String[] args) {
Options o = new Options();
o.execute();
System.out.println(o.pieces);
}
Output is 输出是
523
[5, 2, 3]
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