学了一段时间Android了,一直都是在看,没有什么尝试,刚好最近大致学会了gridview配合simpleadpter的使用,于是想着动手练习一下,就选择了写一个最简单的计算器来实现。
只包含+-*/四种最基本的运算,不过即使是这么简单的小程序也搞了大半天才搞定。也是因为第一次写的时候比较随意,没有画流程图,方法也封装的好,结果后来优化调试的时候特别难受,最后一怒之下删除重新来过,这次注重了整体流程的把握和方法的封装写起来思路清晰了很多,不一会就调试实现了预期的功能,可以说是一次不错的尝试吧!
所以总结就是以后写代码之前尽量先画流程图,然后要注意代码规范和封装,避免文不加点出现过长的方法。
下面是Mainactivity的代码
[code name=java]
package com.fantasy.calculator;
import java.util.ArrayList;
import java.util.HashMap;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.GridView;
import android.widget.SimpleAdapter;
import android.widget.TextView;
public class MainActivity extends Activity implements OnItemClickListener {
private GridView gv; //键盘
private TextView display; //屏幕
private float a, b, sum = 0; //a,b,为两个运算数,sum为运算结果
private int operator = 0; //运算种类标志符
private int equalFlag=0; //按“=”次数标志
String sa = "", temp = ""; //用于接收输入的字符串
/*
* 主界面的图片资源
*/
int[] image = { R.drawable.number7, R.drawable.number8, R.drawable.number9,
R.drawable.division, R.drawable.number4, R.drawable.number5,
R.drawable.number6, R.drawable.multiply, R.drawable.number1,
R.drawable.number2, R.drawable.number3, R.drawable.minus,
R.drawable.number0, R.drawable.dot, R.drawable.equals,
R.drawable.add, R.drawable.clear, R.drawable.off };
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
display = (TextView) findViewById(R.id.textView1);
gv = (GridView) findViewById(R.id.gridView1);
gv.setAdapter(getAdapter(image));
gv.setOnItemClickListener(this);
}
/*
* 为int[]res获取适配的simpleadapter
*/
private SimpleAdapter getAdapter(int[] res) {
ArrayList<HashMap<String, Object>> data = new ArrayList<HashMap<String, Object>>();
for (int i = 0; i < res.length; i++) {
HashMap<String, Object> hashMap = new HashMap<String, Object>();
hashMap.put("button", res[i]);
data.add(hashMap);
}
SimpleAdapter myAdapter = new SimpleAdapter(this, data,
R.layout.buttonitem, new String[] { "button" },
new int[] { R.id.ib_keyboard });
return myAdapter;
}
@Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
// TODO Auto-generated method stub
// 如果按下的是数字键则用temp接收并显示
if (position != 3 && position != 7 && position != 11 && position != 15
&& position != 14 && position != 16 && position != 17) {
temp = getResources().getStringArray(R.array.text)[position];
sa += temp;
b = Float.parseFloat(sa);
display.setText(sa);
}
/*
* 按下运算符和功能键的处理逻辑
*/
switch (position) {
case 3:// 除号按下
equalFlag = 0;
display.setText("\\");
//dividePressed();
operatorPressed(4);
break;
case 7:// 乘号按下
equalFlag = 0;
display.setText("*");
//multiplyPressed();
operatorPressed(3);
break;
case 11:// 减号按下
equalFlag = 0;
display.setText("-");
//subPressed();
operatorPressed(2);
break;
case 15:// 加号按下
equalFlag = 0;
display.setText("+");
//addPressed();
operatorPressed(1);
break;
case 14: // 等号按下
equalFlag++;
showResult();
break;
case 16: // clear按下
clear();
break;
case 17: // 退出按下
this.finish();
break;
default:
break;
}
}
private void addPressed() { //加号按下处理逻辑
// TODO Auto-generated method stub
if (a == 0) {
a = b;
b = 0;
sa = "";
temp = "";
operator = 1;
} else if (operator != 1) {
showResult();
a=sum;
operator = 1;
} else if (operator == 1) {
showResult();
a = sum;
}
}
private void subPressed() {
// TODO Auto-generated method stub
if (a == 0) {
a = b;
b = 0;
sa = "";
temp = "";
operator = 2;
} else if (operator != 2) {
showResult();
a=sum;
operator = 2;
} else if (operator == 2) {
showResult();
a = sum;
}
}
private void multiplyPressed() {
// TODO Auto-generated method stub
if (a == 0) {
a = b;
b = 0;
sa = "";
temp = "";
operator = 3;
} else if (operator != 3) {
showResult();
a=sum;
operator=3;
} else if (operator == 3) {
showResult();
a = sum;
}
}
private void dividePressed() {
// TODO Auto-generated method stub
if (a == 0) {
a = b;
b = 0;
sa = "";
temp = "";
operator = 4;
} else if (operator != 4) {
showResult();
a=sum;
operator = 4;
} else if (operator == 4) {
showResult();
a = sum;
}
}
private void operatorPressed(int sign) {
// TODO Auto-generated method stub
if (a == 0) {
a = b;
b = 0;
sa = "";
temp = "";
operator = sign;
} else if (operator != sign) {
showResult();
a=sum;
operator = sign;
} else if (operator == sign) {
showResult();
a = sum;
}
}
private void showResult() {
// TODO Auto-generated method stub
switch (operator) { //判断运算种类
case 4: //如果是除法
if (equalFlag <= 1) { //如果是第一次按等号 下同
sum = divide(a, b);
display.setText(a+"\\"+b+"="+sum );
sa = "";
temp = "";
} else if (equalFlag >= 2) { //如果是连续按等号 下同
a=sum;
sum = divide(a, b);
display.setText(a+"\\"+b+"="+sum );
}
break;
case 3:
if (equalFlag <= 1) {
sum = multiply(a, b);
display.setText(a+"*"+b+"="+sum );
sa = "";
temp = "";
} else if (equalFlag >= 2) {
a=sum;
sum = multiply(a, b);
display.setText(a+"*"+b+"="+sum );
}
break;
case 2:
if (equalFlag <= 1) {
sum = sub(a, b);
display.setText(a+"-"+b+"="+sum );
sa = "";
temp = "";
} else if (equalFlag >= 2) {
a=sum;
sum = sub(a, b);
display.setText(a+"-"+b+"="+sum );
}
break;
case 1:
if (equalFlag <= 1) {
sum = add(a, b);
display.setText(a+"+"+b+"="+sum );
sa = "";
temp = "";
} else if (equalFlag >= 2) {
a=sum;
sum = add(a, b);
display.setText(a+"+"+b+"="+sum );
}
break;
default:
break;
}
}
// 清空屏幕和缓存
private void clear() {
// TODO Auto-generated method stub
a = b = sum = 0;
operator = 0;
equalFlag=0;
sa = "";
display.setText("");
}
// 加法
private float add(float x, float y) {
return x + y;
}
// 减法
private float sub(float x, float y) {
return x - y;
}
// 乘法
private float multiply(float x, float y) {
return x * y;
}
// 除法
private float divide(float x, float y) {
if (y != 0) {
return (x / y);
} else {
return Float.NaN;
}
}
}
[/code]
说是android其实核心部分是java,因为UI非常丑,网上随便找的图片,然后可以看到本来第一次为+—*/分别写了处理函数,然后写完自己看发现结构是一样的,可以写一个带参数的方法复用,这样就可以精简代码,当然这个只是小程序,看不出效果,如果是大项目的话应该对程序的精简和运行效率的提升都是很有帮助的。