什麼是 Java 物件 getClass() 方法?
Java 使用Object類別提供的名為getClass()的方法來取得所使用的任何物件的類別。方法頭
public final Class<?> getClass()
此方法不帶任何參數,而是在需要取得其類別的物件上呼叫。
返回類型
該方法傳回「物件」的類別。例子
public class DriverClass {
public static void main(String[] args) {
Object myObject = 25;
Class myObjectClass = myObject.getClass();
System.out.println("Class of \"" + myObject + "\" = " + myObjectClass.getName());
myObject = Float.NaN;
myObjectClass = myObject.getClass();
System.out.println("Class of \"" + myObject + "\" = " + myObjectClass.getName());
myObject = Short.MIN_VALUE;
myObjectClass = myObject.getClass();
System.out.println("Class of \"" + myObject + "\" = " + myObjectClass.getName());
myObject = 37.99999999000099990;
myObjectClass = myObject.getClass();
System.out.println("Class of \"" + myObject + "\" = " + myObjectClass.getName());
myObject = Long.MAX_VALUE;
myObjectClass = myObject.getClass();
System.out.println("Class of \"" + myObject + "\" = " + myObjectClass.getName());
myObject = "This is a String.";
myObjectClass = myObject.getClass();
System.out.println("Class of \"" + myObject + "\" = " + myObjectClass.getName());
}
}
輸出
「25」的類別 = java.lang.Integer “NaN”的類別 = java.lang.Float “-32768”的類別 = java.lang.Short “37.999999990001”的類別 = java.lang.Double “9223372036854758075” = java.lang.Long 「這是一個字串」的類別。= java.lang.String
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