Stacks in Java

Learn about Java for a while and summarize the ' stacks ' that have been learned in the last few courses.

About Stacks

Stack is a special linear table that can only be inserted and deleted at one end.

It has a ' last in, first out (LIFO) ' feature.

About the Stack class

Stack class inherits Vector class

The following table is a few ways to stack classes

Boolean	empty() Tests whether the stack is empty.
E	peek() View the object at the top of the stack, but not remove it from the stack.
E	pop() Removes the object at the top of the stack and returns the object as the value of this function.
E	push(E item) Press the item onto the top of the stack.
Int	search(Object o) Returns the position of the object in the stack, with a base of 1.

Instance

Here I'm going to use arrays to implement stacks

PS: I use Java generics here, about Java generics in the previous essay I have introduced.

1 Importjava.util.Arrays;2 3  Public classMystack<e> {4 5     //create a new array of length 06     Privateobject[] src =NewObject[0];7 8     //press data into the stack9      Public voidpush (E s) {Ten         //copy src array, length is the length of the original array +1 OneE[] e = (e[]) arrays.copyof (SRC, src.length + 1); A         //Passes the incoming data to the last element of the new array -E[E.LENGTH-1] =(E) s; -src =e; the     } -  -     //view data at the top of the stack -      PublicE Peek () { +         //returns the last element of the SRC array -         return(E) src[src.length-1]; +     } A  at     //eject data from the top of the stack [remove] -      PublicE Pop () { -         //Copy the SRC array to the new array to make it easier to eject the data at the top of the stack -E[] sr =(e[]) src; -E[] e = (e[]) arrays.copyof (SRC, src.length-1); -src =e; in         return(E) sr[sr.length-1]; -     } to  +     //get the length of the stack -      Public intsize () { the         returnsrc.length; *     } $ Panax Notoginseng     //determine if the stack is empty -      Public Booleanempty () { the         returnSrc.length = = 0; +     } A  the      Public Static voidMain (string[] args) { +Mystack<string> st =NewMystack<string>(); -          $         //press data into the stack $St.push ("AA"); -St.push ("BB"); -St.push ("CC"); theSt.push ("DD"); -         Wuyi         //output stack Top data theSYSTEM.OUT.PRINTLN ("The data at the top of the stack is:" +St.peek ()); -          Wu         //the length of the output stack -System.out.println ("The length of the stack is:" +st.size ()); About          $         //when the stack is not empty, pop up the stack top data -          while(!St.empty ()) { -System.out.println ("Popup Data:" +St.pop ()); -         } A     } +}

Operation Result:

The data at the top of the stack is: DD stack length: 4 Popup data: DD Popup data: CC popup data: BB Popup data: AA

Results analysis

Follow the stack ' LIFO ' feature, enter AA, BB, CC, DD, eject DD, CC, BB, AA.

Based on this feature, stacks are essential at some point.

Stacks in Java