1、代碼模擬:
package org.gzw.ch03;
/**
* 隊列
*/
public class MyQueue {
//底層試用數組
private long[] arr;
//有效數據的長度
private int elements;
//對頭
private int front;
//隊尾
private int end;
/**
* 默認無參構造
*/
public MyQueue(){
arr = new long[10];
elements = 0;
front = 0;
end = -1;
}
/**
* 帶參數的構造方法
*/
public MyQueue(int maxsize){
arr = new long[maxsize];
elements = 0;
front = 0;
end = -1;
}
/**
* 添加數據,從隊尾插入
*/
public void insert(long value){
arr[++end] = value;
elements++;
}
/**
* 刪除數據,從隊頭刪除???
*/
public long remove(){
elements--;
return arr[front++];
}
/**
* 查看數據,從隊頭查看
*/
public long peek(){
return arr[front];
}
/**
* 判斷是否爲空
*/
public boolean isEmpty(){
return elements == 0;
}
/**
* 判斷是否滿了
*/
public boolean isFull(){
//return (end - front) == arr.length;
return elements == arr.length;
}
}
2、測試:
package org.gzw.ch03;
public class TestMyQueue {
public static void main(String[] args) {
MyQueue myQueue = new MyQueue(4);
myQueue.insert(23);
myQueue.insert(45);
myQueue.insert(13);
myQueue.insert(1);
System.out.println(myQueue.isEmpty());
System.out.println(myQueue.isFull());
System.out.println(myQueue.peek());
System.out.println(myQueue.peek());
while(!myQueue.isEmpty()){
System.out.print(myQueue.remove() + ", ");
}
System.out.println();
System.out.println(myQueue.isFull());
System.out.println(myQueue.isEmpty());
//這裏會報錯,原因是end位置在最下面,再插入就會有錯。
myQueue.insert(20);
}
}
3、運行結果:
false
true
23
23
23, 45, 13, 1,
false
true
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 4
at org.gzw.ch03.MyQueue.insert(MyQueue.java:39)
at org.gzw.ch03.TestMyQueue.main(TestMyQueue.java:24)
4、報錯原因:insert(20)後end參數已經在數組的最後位置,在添加就會溢出,處理方法:看下一講循環隊列MyCycleQueue