diff --git a/src/Computer.java b/src/Computer.java
new file mode 100644
index 0000000..1e92811
--- /dev/null
+++ b/src/Computer.java
@@ -0,0 +1,129 @@
+import java.util.Stack;
+
+public class Computer {
+    public double result;//结果
+    public Stack<Character> dataItem;//参与运算数据项
+    public Stack<Double> tempResult;//中间结果
+    public Stack<Character> operator;//运算符号
+
+    public Computer(){
+        init();
+    }
+
+    public void init(){//初始化
+        dataItem=new Stack<Character>();
+        tempResult=new Stack<Double>();
+        dataItem.push('0');
+        operator=new Stack<Character>();
+    }
+
+    public double getResult() {
+        double endItem=0;
+        if(dataItem.empty()){
+            endItem=tempResult.peek();
+        }else{
+            endItem=computerDataItem();
+        }
+        if(operator.empty()){
+            result=endItem;
+            return result;
+        }
+        char c=operator.peek();
+        if (c == '+') {
+            result=tempResult.peek()+endItem;
+        }else if (c == '-') {
+            result=tempResult.peek()-endItem;
+        }else if (c == '*') {
+            result=tempResult.peek()*endItem;
+        }else if (c == '/') {
+            result=tempResult.peek()/endItem;
+        }
+        return result;
+    }
+
+
+    public void setDataItem(char c) {
+        //数据项中不包含小数点时才可以添加小数点
+        if(c!='.')
+            dataItem.push(c);
+        else {
+            if(!dataItem.contains('.'))
+                dataItem.push(c);
+        }
+    }
+
+    public double getTempResult() {
+        double t=0;
+        if(tempResult.empty()){
+            t=computerDataItem();
+        }else{
+            t=tempResult.peek();
+        }
+        return t;
+    }
+
+
+    public char getOperator() {
+        if(operator.empty()){
+            return '\0';
+        }
+        return operator.peek();
+    }
+
+    public void setOperator(char p) {
+        if(dataItem.empty()){
+            operator.clear();//防止重复输入运算符
+            operator.push(p);//保留用户最后确定的运算符
+            return;
+        }
+        if(operator.empty()){
+            operator.push(p);
+            double m=computerDataItem();//计算数据项
+            dataItem.removeAllElements();//清空数据项中的数字
+            tempResult.push(m);//临时结果压入tempResult
+        }else{
+            double m1=computerDataItem();
+            dataItem.removeAllElements();
+            char c= operator.pop();//弹出已有的运算符
+            double t=tempResult.pop();//弹出临时结果
+            if (c == '+') {
+                t=t+m1;
+            }else if (c == '-') {
+                t=t-m1;
+            }else if (c == '*') {
+                t=t*m1;
+            }else if (c == '/') {
+                t=t/m1;
+            }
+            tempResult.push(t);//把新的结果压入tempResult
+            operator.push(p);//把新的运算符压入operator
+        }
+    }
+
+    public double computerDataItem(){//计算出数据项的double型结果
+        if(dataItem.empty()){
+            return tempResult.peek();
+        }
+        StringBuffer sb=new StringBuffer();
+        double doubleData=0;
+        for (int i = 0; i < dataItem.size(); i++) {
+            sb.append(dataItem.get(i));//获取堆栈中的数字但不弹栈
+        }
+        try {
+            doubleData=Double.parseDouble(sb.toString());
+        }catch (NumberFormatException e){
+            doubleData=0;
+        }
+        return doubleData;
+    }
+    public void backspace(){
+        if(dataItem.size()>=1){
+            dataItem.pop();
+        }
+    }
+
+    public void initMath(MathComputer mc){
+        mc.handle(this);
+    }
+
+}