我正在尋找一種簡潔優雅的方法來根據變量值將對象變量轉換為數組。例子：public class Subject { public Subject(boolean music, boolean food, boolean sport, boolean business, boolean art) { this.music = music; this.food = food; this.sport = sport; this.business = business; this.art = art; } private final Long id; private final boolean music; private final boolean food; private final boolean sport; private final boolean business; private final boolean art;}根據每個字段的值，我想將字段名稱作為字符串添加到數組中。例子： new Subject(true, true, true, false, false)預期結果： ["music", "food", "sport"]
3 回答
PIPIONE
TA貢獻1829條經驗 獲得超9個贊
假設沒有吸氣劑，您可以使用反射：
Subject subject = new Subject(true, true, true, false, false);
Field[] fields = Subject.class.getDeclaredFields(); // Get the object's fields
List<String> result = new ArrayList<>();
Object value;
for(Field field : fields) { // Iterate over the object's fields
field.setAccessible(true); // Ignore the private modifier
value = field.get(subject); // Get the value stored in the field
if(value instanceof Boolean && (Boolean)value) { // If this field contains a boolean object and the boolean is set to true
result.add(field.getName()); // Add the field name to the list
}
}
System.out.println(result); // ["music", "food", "sport"]
慕虎7371278
TA貢獻1802條經驗 獲得超4個贊
對于一般解決方案，您可以為此使用反射和 Java Streams：
Subject subject = new Subject(true, true, true, false, false);
String[] trueFields = Arrays.stream(subject.getClass().getDeclaredFields())
.filter(f -> {
f.setAccessible(true);
try {
return f.getBoolean(subject);
} catch (IllegalAccessException e) {
return false;
}
})
.map(Field::getName)
.toArray(String[]::new);
結果將是：
[music, food, sport]
千巷貓影
TA貢獻1829條經驗 獲得超7個贊
您可以使用java的反射來實現這一點
List<String> output = new ArrayList<>();
for(Field f:s.getClass().getDeclaredFields()) {
if((f.getType().equals(boolean.class) || f.getType().equals(Boolean.class)) && f.getBoolean(s)) {
output.add(f.getName());
}
}
System.out.println(output);
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