Android简易计算器

package sugite.love;

import java.util.ArrayList;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class CalculateActivity extends Activity implements OnClickListener {
/** Called when the activity is first created. */
private EditText output;
private EditText input;
private Button btn0;
private Button btn1;
private Button btn2;
private Button btn3;
private Button btn4;
private Button btn5;
private Button btn6;
private Button btn7;
private Button btn8;
private Button btn9;
private Button btnadd;
private Button btnsub;
private Button btnmult;
private Button btndev;
private Button btnclear;
private Button btnreset;
private Button btnleft;
private Button btnright;
private Button btnresult;
char ops[] = { '+', '-', '*', '/', '(', ')', '#' };/* 运算符数组 */
int cmp[][] = { { 2, 2, 1, 1, 1, 2, 2 },/*
* 用来进行比较运算符优先级的矩阵,3代表'=',2代表
* '>',1代表'<',0代表不可比
*/
{ 2, 2, 1, 1, 1, 2, 2 }, { 2, 2, 2, 2, 1, 2, 2 }, { 2, 2, 2, 2, 1, 2, 2 },
{ 1, 1, 1, 1, 1, 3, 0 }, { 2, 2, 2, 2, 0, 2, 2 },
{ 1, 1, 1, 1, 1, 0, 3 } };
StringBuffer str = new StringBuffer();//输入的表达式
boolean flag = true;//能否进行输入的标志

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
output = (EditText) findViewById(R.id.output);
input = (EditText) findViewById(R.id.input);

btn0 = (Button) findViewById(R.id.button_0);
btn1 = (Button) findViewById(R.id.button_1);
btn2 = (Button) findViewById(R.id.button_2);
btn3 = (Button) findViewById(R.id.button_3);
btn4 = (Button) findViewById(R.id.button_4);
btn5 = (Button) findViewById(R.id.button_5);
btn6 = (Button) findViewById(R.id.button_6);
btn7 = (Button) findViewById(R.id.button_7);
btn8 = (Button) findViewById(R.id.button_8);
btn9 = (Button) findViewById(R.id.button_9);

btnadd = (Button) findViewById(R.id.button_add);
btnsub = (Button) findViewById(R.id.button_sub);
btnmult = (Button) findViewById(R.id.button_mult);
btndev = (Button) findViewById(R.id.button_dev);
btnleft = (Button) findViewById(R.id.button_lc);
btnright = (Button) findViewById(R.id.button_rc);

btnclear = (Button) findViewById(R.id.button_clr);
btnreset = (Button) findViewById(R.id.button_reset);
btnresult = (Button) findViewById(R.id.button_is);

btn0.setOnClickListener(this);
btn1.setOnClickListener(this);
btn2.setOnClickListener(this);
btn3.setOnClickListener(this);
btn4.setOnClickListener(this);
btn5.setOnClickListener(this);
btn6.setOnClickListener(this);
btn7.setOnClickListener(this);
btn8.setOnClickListener(this);
btn9.setOnClickListener(this);
btnleft.setOnClickListener(this);
btnright.setOnClickListener(this);
btnadd.setOnClickListener(this);
btnsub.setOnClickListener(this);
btnmult.setOnClickListener(this);
btndev.setOnClickListener(this);
btnclear.setOnClickListener(this);
btnreset.setOnClickListener(this);
btnresult.setOnClickListener(this);

}

@Override
public void onClick(View view) {
switch (view.getId()) {
case R.id.button_0:
SetInput('0');
break;
case R.id.button_1:
SetInput('1');
break;
case R.id.button_2:
SetInput('2');
break;
case R.id.button_3:
SetInput('3');
break;
case R.id.button_4:
SetInput('4');
break;
case R.id.button_5:
SetInput('5');
break;
case R.id.button_6:
SetInput('6');
break;
case R.id.button_7:
SetInput('7');
break;
case R.id.button_8:
SetInput('8');
break;
case R.id.button_9:
SetInput('9');
break;
case R.id.button_add:
SetInput('+');
break;
case R.id.button_sub:
SetInput('-');
break;
case R.id.button_mult:
SetInput('*');
break;
case R.id.button_dev:
SetInput('/');
break;
case R.id.button_lc:
SetInput('(');
break;
case R.id.button_rc:
SetInput(')');
break;
case R.id.button_clr:
Init();
break;
case R.id.button_reset://重置
if (str.length() > 0 && flag) {
str.deleteCharAt(str.length() - 1);
input.setText(str);
output.setText("");
}
break;
case R.id.button_is://“=” 进行求值
if (str.length() > 0) {
str.append('#');
ExpEvaluation();
}
}
}

public void SetInput(char ch) {
if (flag) {
str.append(ch);
input.setText(str);
}
}

private void ExpEvaluation() {//表达式求值的函数
int i = 0, temp;
char op;
float a, b, v;
ArrayList<Character> operator = new ArrayList<Character>(50);
ArrayList<Float> operand = new ArrayList<Float>(50);
operator.add(new Character('#'));
char ch = str.charAt(i++);
while (ch != '#'
|| operator.get(operator.size() - 1).charValue() != '#') {
if (!IsOperator(ch)) {//如果不是操作符
temp = ch - '0';
ch = str.charAt(i++);
while (!IsOperator(ch)) {
temp = temp * 10 + ch - '0';
if (temp >= Integer.MAX_VALUE / 10) {
output.setText("超出计算范围,按C清零,重新输入!");
flag = false;
return;
}
ch = str.charAt(i++);
}
operand.add(new Float((float) temp));
} else {
switch (Compare(operator.get(operator.size() - 1).charValue(),
ch)) {
case '<':
operator.add(new Character(ch));
ch = str.charAt(i++);
break;
case '=':
op = operator.remove(operator.size() - 1).charValue();
ch = str.charAt(i++);
break;
case '>':
op = operator.remove(operator.size() - 1).charValue();
if (operand.size() < 2) {
output.setText("表达式错误,请按C清零,重新输入！");
flag = false;
return;
}
b = operand.remove(operand.size() - 1).floatValue();
a = operand.remove(operand.size() - 1).floatValue();
v = Execute(a, op, b);
operand.add(new Float(v));
break;
}
}
}
v = operand.remove(operand.size() - 1).floatValue();
output.setText(new Float(v).toString());
str.delete(0, str.length());
flag = false;
}

private void Init() {//初始化计算器
input.setText("");
output.setText("");
str.delete(0, str.length());
flag = true;
}

private float Execute(float a, char op, float b) {//二元表达式求值
float result = 0.0f;
switch (op) {
case '+':
result = a + b;
break;
case '-':
result = a - b;
break;
case '*':
result = a * b;
break;
case '/':
result = a / b;
break;
}
return result;
}

public boolean IsOperator(char c) {//判断是否为操作符
for (int i = 0; i < 7; i++)
if (c == ops[i])
return true;
return false;
}

public char Compare(char ch1, char ch2) { /* 比较运算符优先级函数 */
int i, m = 0, n = 0;
char pri = 0;
int priority;
for (i = 0; i < 7; i++) { /* 找到相比较的两个运算符在比较矩阵里的相对位置 */
if (ch1 == ops[i])
m = i;
if (ch2 == ops[i])
n = i;
}
priority = cmp[m]
;
switch (priority) {
case 1:
pri = '<';
break;
case 2:
pri = '>';
break;
case 3:
pri = '=';
break;
case 0:
System.out.println("表达式错误!\n");
System.exit(0);
break;
}
return pri;
}
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#FEDAD7"
>
<TextView  android:layout_width="fill_parent"  android:layout_height="wrap_content"
android:text="@string/hello"   android:textSize="20.0dip"/>
<EditText android:layout_width="fill_parent" android:layout_height="wrap_content"
android:maxLines="2" android:id="@+id/input" android:editable="false"/>
<EditText android:layout_width="fill_parent" android:layout_height="wrap_content"
android:maxLines="1" android:id="@+id/output" android:editable="false"
android:gravity="right"/>
<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="wrap_content">
<TableRow android:gravity="center">
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_7" android:text="7" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_8" android:text="8" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_9" android:text="9" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_add" android:text="+" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_sub" android:text="-" android:textSize="40.0dip"/>
</TableRow>
<TableRow android:gravity="center">
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_4" android:text="4" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_5" android:text="5" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_6" android:text="6" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_mult" android:text="×" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_dev" android:text="÷" android:textSize="40.0dip"/>
</TableRow>
<TableRow android:gravity="center">
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_1" android:text="1" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_2" android:text="2" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_3" android:text="3" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_lc" android:text="(" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_rc" android:text=")" android:textSize="40.0dip"/>
</TableRow>
<TableRow android:gravity="center">
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_0" android:text="0" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_clr" android:text="C" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_reset" android:text="R" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_is" android:text="=" android:textSize="40.0dip"/>
<Button android:layout_width="60px" android:layout_height="wrap_content"
android:id="@+id/button_point" android:text="." android:textSize="40.0dip"/>
</TableRow>
</TableLayout>
</LinearLayout>