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[英]How do I get the type of an object's variable if I know the name of the variable in java?
[英]How can I get as an output the name of a variable and it's type in Java?
我有以下課程:
public class Example {
private String name;
private int year;
public Example() {
name = "Clifford the big red dog";
year = 2020;
}
public void showData() {
// ?????
}
}
想象一下,在主類中,我創建了前一個類( Example
)的對象並執行它的構造函數。 然后我想執行showData()
並且我想看到以下輸出(給定這個例子):
String name Clifford the big red dog
int year 2020
主要看起來像這樣:
public static void main () {
Example example = new Example();
example.showData();
}
有什么辦法可以做到這一點嗎?
請按以下步驟操作:
class Example {
private String name;
private int year;
public Example() {
name = "Clifford the big red dog";
year = 2020;
}
public void showData() {
System.out.println(name.getClass().getSimpleName() + " name " + name);
System.out.println(((Object) year).getClass().getSimpleName() + " year " + year);
}
}
public class Main {
public static void main(String[] args) {
Example example = new Example();
example.showData();
}
}
輸出:
String name Clifford the big red dog
Integer year 2020
然而,由於showData
是class Example
一個方法,它已經知道它的實例變量,你可以簡單地這樣做:
class Example {
private String name;
private int year;
public Example() {
name = "Clifford the big red dog";
year = 2020;
}
public void showData() {
System.out.println("String name " + name);
System.out.println("int year " + year);
}
}
public class Main {
public static void main(String[] args) {
Example example = new Example();
example.showData();
}
}
輸出:
String name Clifford the big red dog
int year 2020
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