我正在创建一个Slick2D游戏。现在，我正在创建一个Video类，它包含内部类（FrameSize，FPS，FullScreen ..）。所以我有一个OOD的想法，就像我们调用System.out.println（）一样。这意味着我将拥有内部clasess的公共Video类和公共静态实例，但netbeans IDE向我提示“通过公共API导出非公共类型”。那么，我应该忽略这一点并继续按照我的方式行事，或者如果你可以向我推荐你的想法会很棒吗？
VIDEO
public class Video {
public static FrameSize frameSize;
public static FullScreen fullScreen;
public static FPS fps;
private Video() {}
public static void loadArguments(Scanner loadInput) {
boolean isVideo = false;
String readLine;
while (loadInput.hasNext()) {
readLine = loadInput.next();
if (readLine.equalsIgnoreCase("video")) {
isVideo = true;
break;
}
}
while (isVideo && loadInput.hasNext()) {
readLine = loadInput.next();
if (readLine.equalsIgnoreCase("end")) {
break;
}
String[] line = readLine.split("=");
String key = line[0];
String value = line[1];
switch (key) {
case "width":
frameSize.setWidth(Integer.parseInt(value));
break;
case "height":
frameSize.setHeight(Integer.parseInt(value));
break;
case "fullscreen":
break;
case "fps":
break;
default:
System.err.println("Unknown video key: " + key);
break;
}
}
}
public static void saveArguments(String filePath) {
Scanner saveInput;
try {
saveInput = new Scanner(new File(filePath));
} catch (FileNotFoundException fne) {
System.err.println("Invalid settings-file.");
return;
}
// TO DO: save function
saveInput.close();
}
class FrameSize {
public final int[][] SIZE_VALUES = {
{800, 600},
{1000, 700},
{1200, 800},
{1400, 900}
};
private int index;
private int width, height;
private FrameSize() {}
public void setSize(int width, int height) {
this.width = width;
}
public int getWidth() {
return width;
}
public void setWidth(int width) {
this.width = width;
}
public int getHeight() {
return height;
}
public void setHeight(int height) {
this.height = height;
}
@Override
public String toString() {
return this.width + " x " + this.height;
}
}
class FullScreen {
private boolean fullScreen;
private FullScreen() {}
public boolean isFullScreen() {
return fullScreen;
}
public void setFullScreen(boolean fullScreen) {
this.fullScreen = fullScreen;
}
@Override
public String toString() {
return "" + fullScreen;
}
}
class FPS {
private boolean FPS;
private FPS() {}
public boolean isFPS() {
return FPS;
}
public void setFPS(boolean FPS) {
this.FPS = FPS;
}
@Override
public String toString() {
return "" + fps;
}
}
}
AUDIO
public class Audio {
private static Sound sound;
private static Volume volume;
private Audio() {}
public void loadArguments(Scanner loadInput) {
boolean isAudio = false;
String readLine;
while (loadInput.hasNext()) {
readLine = loadInput.next();
if (readLine.equalsIgnoreCase("audio")) {
isAudio = true;
break;
}
}
while (isAudio && loadInput.hasNext()) {
readLine = loadInput.next();
if (readLine.equalsIgnoreCase("end")) {
break;
}
String[] line = readLine.split("=");
String key = line[0];
String value = line[1];
switch (key) {
case "sound":
break;
case "volume":
break;
default:
System.err.println("Unknown audio key: " + key);
break;
}
}
}
public void saveArguments(String filePath) {
Scanner saveInput;
try {
saveInput = new Scanner(new File(filePath));
} catch (FileNotFoundException fne) {
System.err.println("Invalid settings-file.");
return;
}
// TO DO: save function
saveInput.close();
}
class Sound {
private boolean sound;
private Sound() {}
public boolean isSound() {
return sound;
}
public void setSound(boolean sound) {
this.sound = sound;
}
@Override
public String toString() {
return "" + sound;
}
}
class Volume {
private static final double PITCH = 0.1d;
private double volume;
private Volume() {}
public double getVolume() {
return volume;
}
public void setVolume(double volume) {
this.volume = volume;
}
public void increaseVolume() {
if (!isVolumeRange(this.volume)) {
return;
}
this.volume = this.volume + PITCH;
}
public void decreaseVolume() {
if (!isVolumeRange(this.volume)) {
return;
}
this.volume = this.volume - PITCH;
}
public boolean isVolumeRange(double volume) {
return volume >= 0.0 && volume <= 10.0;
}
}
}
答案 0 :(得分：11)
Video类包含类型为frameSize的公共类变量FrameSize的声明。
public修饰符表示frameSize变量对所有人都可见。
package package1;
public class Video {
public static FrameSize frameSize;
}
// private class
class FrameSize {
}
但是FrameSize是本地类 - 它只对同一个包的成员可见。在上面的示例中，只有包package1的成员才能看到该类，并且下面的代码编译得很好：
package package1;
public class Test {
void test(){
FrameSize x = Video.frameSize;
}
}
但是这段代码（不同的包）会产生编译错误：
package package2;
import package1.*;
public class Test {
void test(){
// this line won't compile - FrameSize class is unknown
FrameSize x = Video.frameSize;
// but this line compiles fine - Object class is public
Object y = Video.frameSize;
}
}
NetBeans警告你这一点，因为很可能是无意的错误 - 为什么你想让所有人都可以访问一些字段值而不发布这个字段的类型，这实际上阻止他们使用那个字段？
如果您想让变量只能访问同一个包中的其他类，请将其声明为protected，而不是public。
但如果是故意声明 - 则忽略警告并保持原样。