java - 在没有 arrayList 的情况下向数组添加元素

Question

我正在尝试定义一个名为 add() 的方法，它将对象 Fish 添加到数组 Fish[] 中。如果不使用 arrayList 我该如何解决这个问题？我不断收到错误: 线程“main”中的异常 java.lang.ArrayIndexOutOfBoundsException: 1

public class Pond {
private Fish[] fish;
private int numFish ;
private int capacity;

public Pond(int capacity){
    this.capacity = capacity;
}
public int getNumFish(){ return numFish;
}
public boolean isFull(){//Ponds can only have so many fish
    boolean Full = false;
    if (numFish >= capacity){
        Full = true;}
    return Full;
}
public void add(Fish aFish) {// puts a fish in the pond--OR-- replaces a fish that has been temporarily removed 
    if (numFish < capacity){
        fish[numFish++] = aFish;}
}

Answer 1

这里是动态数组解决方案，它是 ArrayList 方法的简单实现。

public void add(Fish aFish) {
    ensureCapacity();
    fish[numFish++] = aFish;
}

private void ensureCapacity() {
    if (numFish == fish.length) {
        int newSize = fish.length * 2;
        Fish[] newFish = new Fish[newSize];

        System.arraycopy(fish, 0, newFish, 0, fish.length);
        fish = newFish;
    }
}