Java string allocates memory space memo

Stack memory Heap Memory ) access speed slower than stack memory The allocated memory is managed by the Java Virtual Machine automatic garbage collector 。 Dynamically allocating memory size Shared features if not, open up a new space deposit value Each new object is generated in heap memory at a time. Value can be changed after creation String cannot be changed after the class declaration One, stack memory base Type int, short, long, byte, float, double, boolean, Char and Object references Sharing features of Stacks String str1 = "abc"; String str2 = "abc"; System.out.println (STR1==STR2); True 1 , the compiler processes string str1 = "abc"; it creates a reference in the stack with a variable of str1, and then looks for the value of ABC in the stack, if it is not found, stores the ABC in, and then points the STR1 to ABC. 2 , and then processing string str2 = "abc", after creating the reference variable of B, because the value of ABC is already in the stack, it points str2 directly to ABC. In this way, the str1 and str2 both point to the ABC situation. Second, heap memory New , NewArray, Anewarray and Multianewarray, and other directives established Note: When defining a class using a format such as String str = "ABC", we always want to assume, of course, that the object of the string class was created by Str. Worry about traps! The object may not have been created! Instead, it might just point to an object that was previously created. Only through the new () method can you guarantee that a new object is created each time. Because of the immutable nature of the string class, you should consider using the StringBuffer class to improve program efficiency when a string variable needs to change its value frequently. Third, = = memory address comparison String str1 = "abc"; String str2 = "abc"; System.out.println (STR1==STR2); True str1 and str2 simultaneously point to the same memory space in the stack memory String STR3 = "abc"; String STR4 = new String ("abc"); System.out.println (Str3 = = STR4); Flase STR3 value in stack memory, STR4 value in heap memory String Hello = "Hello"; String hel = "hel"; String lo = "Lo"; System.out.println (Hello = = "hel" + "lo"); True // two constants added, first detect if there is a hello in the stack memory if yes, point to the existing stack in the Hello space System.out.println (Hello = = "hel" + lo); Flase System.out.println (Hello = = hel + lo); Flase //lo is in the constant pool, does not check the stack memory, generates a new hello in the heap Four, the equals value of the comparison public boolean equals(Object anobject) Compares this string to the specified object. The result is true if and only if the parameter is not NULL and is a String object that represents the same sequence of characters as this object. String STR5 = "abc"; String STR6 = new String ("abc"); System.out.println (Str5.equals (STR6)); True STR5 value of STR6 is compared to the value of v. Memory address of the value in the intern stack Public String Intern () When you call the Intern method 1 , if the pool already contains a string equal to this string object (as determined by the Equals (Object) method), the string in the pool is returned. 2 , adds this string object to the pool, and returns a reference to this string object. String s7 = new String ("abc"); String s8 = "abc"; System.out.println (s7 = = S7.intern ());//flase ; System.out.println (S8 = = S7.intern ());//true 1. Check the stack memory for any ABC objects if there is 2. Point the S7 to the pool ABC

Java string allocates memory space memo