Question

我正在尝试从文本文件中读取对象类的参数。该类只需要一个参数int id。其余三个参数是可选的，如果没有提供，则由对象构造函数确定。

文本文件按以下格式生成：

View source

示例：

Inspect element

以下是我目前阅读此格式文件的代码：

`R|G id [volume] [hasESP] [isVegetarian]
int id, int volume, boolean hasESP, boolean isVegitarian

我可以在这里切换使用哪个构造函数，但我无法弄清楚如何找到输入的模式并相应地使用它，所以我没有得到RunTime错误或InvalidArgument错误。任何帮助表示赞赏。

Answer 1

使用构建器模式，您可以轻松完成。代码示例包含一些lambda。如果你正在使用＆lt; jdk8，你可以将lambda转换为常规方法。

class Martian {

private String type;
private int id;
private int volume;
private boolean hasESP;
private boolean isVegitarian;

public Martian(String type, int id, int volume, boolean hasESP,
    boolean isVegitarian) {
    this.type = type;
    this.id = id;
    this.volume = volume;
    this.hasESP = hasESP;
    this.isVegitarian = isVegitarian;
}

public String getType() {
    return type;
}

public int getId() {
    return id;
}

public int getVolume() {
    return volume;
}

public boolean isHasESP() {
    return hasESP;
}

public boolean isVegitarian() {
    return isVegitarian;
}

public static MartianBuilder builder() {
    return new MartianBuilder();
}

static class MartianBuilder {

    private String type;
    private int id;
    private int volume;
    private boolean hasESP;
    private boolean isVegitarian;

    public MartianBuilder type(String type) {
        this.type = type;
        return this;
    }

    public MartianBuilder id(int id) {
        this.id = id;
        return this;
    }

    public MartianBuilder volume(int volume) {
        this.volume = volume;
        return this;
    }

    public MartianBuilder hasESP(boolean hasESP) {
        this.hasESP = hasESP;
        return this;
    }

    public MartianBuilder vegitarian(boolean vegitarian) {
        isVegitarian = vegitarian;
        return this;
    }

    public Martian build() {
        return new Martian(type, id, volume, hasESP, isVegitarian);
    }
}

这是您可以使用上面的构建器

的方法

public class MartianExample {

void readMartianFile(File file) throws IOException {
    BufferedReader br = new BufferedReader(new FileReader(file));
    String line;

    while ((line = br.readLine()) != null) {
        String[] split = line.split(" ");
        Martian martian = createMartian(split);
        // Decide what to do with read data
    }
}

private Martian createMartian(String[] rawData) {
    MartianBuilder builder = Martian.builder();
    int counter = 0;
    // read type
    counter = readData(builder::type, counter, rawData);

    // read id
    counter = readData((idString) -> builder.id(Integer.parseInt(idString)), counter,
        rawData);

    // read volume
    counter = readData((volumeString) -> builder.volume(Integer.parseInt(volumeString)),
        counter, rawData);

    // read hasESP
    counter = readData((hasESPString) -> builder.hasESP(Boolean.parseBoolean(hasESPString)),
        counter, rawData);

    // read isVegitarian
    counter = readData((isVegitarianString) -> builder.vegitarian(Boolean.parseBoolean
        (isVegitarianString)), counter, rawData);

    return builder.build();
}

private int readData(Consumer<String> consumer, int counter, String[] rawData) {
    if (counter < rawData.length) {
        consumer.accept(rawData[counter]);
        counter++;
    }
    return counter;
}

使用Java Scanner读取同一对象的多个模式

1 个答案: