在Java中someobject.class是什么意思？[副本]

Question

public class Singleton {
private volatile static Singleton uniqueInstance;
private Singleton() {}
public static Singleton getInstance() {
    if (uniqueInstance == null) {
        synchronized (Singleton.class) {
    if (uniqueInstance == null) {
        uniqueInstance = new Singleton();
    }
}
}
return uniqueInstance;
}
}

Answer 1

它表示该类的class对象。一旦获得class对象，就可以执行许多操作，比如获取类的字段、类的方法、类的包等等。

最常见的是，您将使用它以流的形式获取资源。也就是说，当您想要从jar文件中检索嵌入的资源时。有关更多详细信息，请参阅文档

直接在http://ideone.com/h1czr5运行下面的代码

/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;
import java.lang.reflect.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
    public static void main (String[] args) throws java.lang.Exception
    {
        Class string = String.class;

        System.out.println("Package: " + string.getPackage());
        System.out.println("Fields: " + java.util.Arrays.toString(string.getFields()));
        Method[] methods = string.getMethods();

        for(int i = 0; i < 10; i++){
            System.out.println(methods[i]);
        }

    }
}  

Package: package java.lang, Java Platform API Specification, version 1.7
Fields: [public static final java.util.Comparator java.lang.String.CASE_INSENSITIVE_ORDER]
public boolean java.lang.String.equals(java.lang.Object)
public java.lang.String java.lang.String.toString()
public int java.lang.String.hashCode()
public int java.lang.String.compareTo(java.lang.Object)
public int java.lang.String.compareTo(java.lang.String)
public int java.lang.String.indexOf(java.lang.String,int)
public int java.lang.String.indexOf(int)
public int java.lang.String.indexOf(int,int)
public int java.lang.String.indexOf(java.lang.String)
public static java.lang.String java.lang.String.valueOf(float)