Java代码实现顺序栈和链式栈
栈(stack)又名堆栈，它是一种运算受限的线性表。其限制是仅允许在表的一端进行插入或者删除运算。后进先出（Last In First Out）。
栈中的数据操作主要有push(压入)和pop(弹出)操作。
实际上，栈就可以用数组来实现，也可以用链表来实现。用数组实现的叫做顺序栈，用链表实现的叫做链式栈。
为了简单起见，我们的栈不支持泛型。
顺序栈
public class StackBasedArray implements StackInterface{
private String[] values; // 存储栈中元素的数组
private int capacity;// 栈的容量
private int count;// 栈中已有数据个数
// 初始化栈，容量确定。
public StackBasedArray(int capacity) {
this.values = new String[capacity];
this.capacity = capacity;
this.count = 0;
}
/**
* 入栈操作
*
* @param value
* @return
*/
public Boolean push(String value) {
// 数组空间不够了
if (capacity == count) {
return false;
}
values[count] = value;
count++;
return true;
}
/**
* 出栈操作
*
* @return
*/
public String pop() {
// 栈为空，则直接返回null
if (0 == count) {
return null;
}
String tmp = values[count - 1];
--count;
return tmp;
}
@Override
public String toString() {
return "StackBasedArray{" +
"values=" + Arrays.toString(values) +
", capacity=" + capacity +
", count=" + count +
'}';
}
}测试代码：
StackBasedArray as = new StackBasedArray(10);
System.out.println(as);
Boolean r1 = as.push("000");
System.out.println(as + ",r1:" + r1);
for (int i = 1; i < 11; i++) {
boolean r2 = as.push("" + i + i + i);
System.out.println(as + ",r2:" + r2);
}
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);
System.out.println("as.pop():" + as.pop() + "," + as);输出结果：符合预期
StackBasedArray{values=[null, null, null, null, null, null, null, null, null, null], capacity=10, count=0}
StackBasedArray{values=[000, null, null, null, null, null, null, null, null, null], capacity=10, count=1},r1:true
StackBasedArray{values=[000, 111, null, null, null, null, null, null, null, null], capacity=10, count=2},r2:true
StackBasedArray{values=[000, 111, 222, null, null, null, null, null, null, null], capacity=10, count=3},r2:true
StackBasedArray{values=[000, 111, 222, 333, null, null, null, null, null, null], capacity=10, count=4},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, null, null, null, null, null], capacity=10, count=5},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, 555, null, null, null, null], capacity=10, count=6},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, null, null, null], capacity=10, count=7},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, null, null], capacity=10, count=8},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, null], capacity=10, count=9},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=10},r2:true
StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=10},r2:false
as.pop():999,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=9}
as.pop():888,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=8}
as.pop():777,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=7}
as.pop():666,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=6}
as.pop():555,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=5}
as.pop():444,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=4}
as.pop():333,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=3}
as.pop():222,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=2}
as.pop():111,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=1}
as.pop():000,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=0}
as.pop():null,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=0}
as.pop():null,StackBasedArray{values=[000, 111, 222, 333, 444, 555, 666, 777, 888, 999], capacity=10, count=0}链式栈
使用链表来实现栈，push进的数据添加至链表的头结点，pop数据时取的也是链表的头结点，这样就实现了栈的后进先出。代码如下：
public class StackBasedLinkedList implements StackInterface {
private Node first;
/**
* 每次添加数据都向链表头结点添加。
*
* @param value
* @return
*/
@Override
public Boolean push(String value) {
Node newNode = new Node(value, null);
if (null == first) {
first = newNode;
} else {
newNode.next = first;
first = newNode;
}
return true;
}
/**
* 每次获取数据都从链表头结点获取。
*
* @return
*/
@Override
public String pop() {
if (null == first) {
return null;
} else {
String tmp = first.getValue();
first = first.next;
return tmp;
}
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append('[');
if (first != null) {
Node curr = first;
while (curr != null) {
sb.append(String.valueOf(curr));
if (curr.next != null) {
sb.append(",").append(" ");
}
curr = curr.next;
}
}
sb.append("]");
return sb.toString();
}
private static class Node {
Node next;
String value;
public Node(String value, Node next) {
this.next = next;
this.value = value;
}
public String getValue() {
return value;
}
@Override
public String toString() {
return value;
}
}
}测试代码：
StackBasedLinkedList sbll = new StackBasedLinkedList();
System.out.println(sbll);
// 添加数据
for (int i = 0; i < 10; i++) {
sbll.push("" + i + i + i);
}
System.out.println(sbll);
// 获取数据
for (int i = 0; i < 11; i++) {
System.out.println("sbll.pop():" + sbll.pop());
}输出结果：符合预期。
[]
[999, 888, 777, 666, 555, 444, 333, 222, 111, 000]
sbll.pop():999
sbll.pop():888
sbll.pop():777
sbll.pop():666
sbll.pop():555
sbll.pop():444
sbll.pop():333
sbll.pop():222
sbll.pop():111
sbll.pop():000
sbll.pop():null完整代码请查看
项目中搜索SingleLinkedList即可。
github传送门 https://github.com/tinyvampirepudge/DataStructureDemo
