Javaの定数プールとは何ですか? Java 定数プールの概要

Integer integer1 = 127;
Integer integer2 = 127;
System.out.println(integer1 == integer2);
// true
Integer integer1 = 128;
Integer integer2 = 128;
System.out.println(integer1 == integer2);
// false

String string1 = "dashu";
String string2 = "dashu";
System.out.println(string1==string2);
// true

String string1 = "dashu";
String string3 = new String("dashu");
System.out.println(string1 == string3);
// false

// 源码
public class Object{
 private static native void registerNatives();
 static{
  registerNatives();
 }
}
// 源码
public boolean equals(Object obj){
 return (this == obj);
}
// 源码
public String toString(){
 return getClass().getName() + "@" + Integer.toHexString(hasCode());
}
// 源码
protected native Object clone() throws CloneNotSupportedException;

万物皆对象
// 源码注解
Class {@code Object} is the root of the  class hierarchy.
Every class has {@code Object} as a superclass.
All objects, including arrays, implements the methods of this class.
@ see java.lang Class
@ since JDK1.0

String string1 = "dashu";
String string3 =  new String("dashu");
System.out.println(string1==string3.intern());