java学习之JVM运行时常量池理解

public class NotInitialzation {
    public static void main(String[] args) {
//        System.out.println(SubClass.value);
//        SubClass sbc = new SubClass();
        Integer inte = 10;
        Integer inte1 = 3 + 4;
        Integer a = new Integer(3);
        Integer b = new Integer(4);
        Integer c = a + b;
        Integer d = new Integer(7);
        System.out.println(inte1 == c);//true
        System.out.println(c == a + b);//true
        System.out.println(c == d);//false
        System.out.println("=====================================================");
        String str = "abcd";
        String str1 = "ab";
        String str2 = "abcd" + "ab";
        String str3 = str + str1;
        String str4 = "abcdab";
        System.out.println(str3 == str2);//false
        System.out.println(str2 == str4);//true

    }
}

// Decompiled by Jad v1.5.8e2. Copyright 2001 Pavel Kouznetsov.
// Jad home page: http://kpdus.tripod.com/jad.html
// Decompiler options: packimports(3) fieldsfirst ansi space 
// Source File Name:   NotInitialzation.java
import java.io.PrintStream;
public class NotInitialzation
{
	public NotInitialzation()
	{
	}
	public static void main(String args[])
	{
		Integer inte = Integer.valueOf(10);
		Integer inte1 = Integer.valueOf(30);
		Integer a = new Integer(3);
		Integer b = new Integer(4);
		Integer c = Integer.valueOf(a.intValue() + b.intValue());
		Integer d = new Integer(7);
		System.out.println(c.intValue() == a.intValue() + b.intValue());
		System.out.println(c == d);
		System.out.println("=====================================================");
		String str = "abcd";
		String str1 = "ab";
		String str2 = "abcdab";
		String str3 = (new StringBuilder()).append(str).append(str1).toString();
		String str4 = "abcdab";
		System.out.println(str3 == str2);
		System.out.println(str2 == str4);
	}
}