如何在Java中过滤数组? [英] How to filter an array in Java?

问题描述

如何在 Java 中过滤数组?

How can I filter an array in Java?

我有一组对象，例如汽车:

I have an array of objects, for example cars:

类:

public class Car{
    public int doors;
    public Car(int d){
        this.doors = d;
    }
}

使用:

Car [] cars = new Cars[4];
cars[0] = new Car(3);
cars[1] = new Car(2);
cars[2] = new Car(4);
cars[3] = new Car(6);

现在我想过滤汽车数组，只保留 4 扇门和更多:

Now I want to filter the array of cars, keeping only 4 doors and more:

for(int i = 0; i<cars.length; i++){
    if(cars[i].doors > 4)
         //add cars[i] to a new array
    }
}

我该怎么做?

在我使用 Vector 之前:

Before I did it with a Vector:

Vector subset = new Vector();
for(int i = 0; i<cars.length; i++){
    if(cars[i].doors > 4)
         //add cars[i] to a new array
        subset.addElement(cars[i]);
    }
}

然后我将创建一个具有 Vector 大小的新数组.然后我会再次遍历向量并填充新数组.我知道对于简单的事情来说这是一个非常大的过程.

And then I would make a new array with the size of the Vector. Then I would loop over the vector again and fill the new array. I know this is a very large procedure for something simple.

我使用的是 J2ME.

推荐答案

看到 ArrayList 不在 J2ME 中，但根据文档，它确实有一个 Vector.如果该 Vector 类与 J2SE Vector 不同(如 本文档表示)，那么下面的代码可能会起作用:

saw that ArrayList is not in J2ME, but based on documentation, it does have a Vector. If that Vector class is different than J2SE Vector (as this documentation indicates), then perhaps the following code would work:

Vector carList = new Vector();
for(int i = 0; i<cars.length; i++){
    if(cars[i].doors > 4)
         carList.addElement(cars[i]);
    }
}
Car[] carArray = new Car[carList.size()];
carList.copyInto(carArray);

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