我正在尋找一種簡(jiǎn)潔優(yōu)雅的方法來根據(jù)變量值將對(duì)象變量轉(zhuǎn)換為數(shù)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(jù)每個(gè)字段的值，我想將字段名稱作為字符串添加到數(shù)組中。例子： new Subject(true, true, true, false, false)預(yù)期結(jié)果： ["music", "food", "sport"]
3 回答
PIPIONE
TA貢獻(xiàn)1829條經(jīng)驗(yàn) 獲得超9個(gè)贊
假設(shè)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(xiàn)1802條經(jīng)驗(yàn) 獲得超4個(gè)贊
對(duì)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(jié)果將是：
[music, food, sport]
千巷貓影
TA貢獻(xiàn)1829條經(jīng)驗(yàn) 獲得超7個(gè)贊
您可以使用java的反射來實(shí)現(xiàn)這一點(diǎn)
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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