计算器

package com.example.calculator;


import java.math.BigDecimal;


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


public class MainActivity extends Activity {
private String str = "";
private EditText et;
// sing符号，flag暂存
private int sign = 0, flag = 0;
private double n1 = 0.0, n2 = 0.0, r = 0.0;
private Button de;
private BigDecimal t1;
private BigDecimal t2;
private BigDecimal t;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et = (EditText) findViewById(R.id.edit_show);
de=(Button)findViewById(R.id.delete);
de.setOnLongClickListener(new OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
n1=0;
n2=0;
r=0;
str="";
et.setText(str);
return false;
}
});
}
public void doClick(View view) {
switch (view.getId()) {
case R.id.zero:
if (flag == 1) {
str = "";
str += 0;
et.setText(str);
flag = 0;
} else {
char[] c1 = str.toCharArray();
if (!(c1.length == 1 && c1[0] == '0')) {
str += 0;
et.setText(str);
}
}
break;
case R.id.one:
if (flag == 1) {
str = "";
str += 1;
et.setText(str);
flag = 0;
} else {
str += 1;
et.setText(str);
}
break;
case R.id.two:
if (flag == 1) {
str = "";
str += 2;
et.setText(str);
flag = 0;
} else {
str += 2;
et.setText(str);
}
break;
case R.id.three:
if (flag == 1) {
str = "";
str += 3;
et.setText(str);
flag = 0;
} else {
str += 3;
et.setText(str);
}
break;
case R.id.four:
if (flag == 1) {
str = "";
str += 4;
et.setText(str);
flag = 0;
} else {
str += 4;
et.setText(str);
}
break;
case R.id.five:
if (flag == 1) {
str = "";
str += 5;
et.setText(str);
flag = 0;
} else {
str += 5;
et.setText(str);
}
break;
case R.id.six:
if (flag == 1) {
str = "";
str += 6;
et.setText(str);
flag = 0;
} else {
str += 6;
et.setText(str);
}
break;
case R.id.seven:
if (flag == 1) {
str = "";
str += 7;
et.setText(str);
flag = 0;
} else {
str += 7;
et.setText(str);
}
break;
case R.id.eight:
if (flag == 1) {
str = "";
str += 8;
et.setText(str);
flag = 0;
} else {
str += 8;
et.setText(str);
}
break;
case R.id.nine:
if (flag == 1) {
str = "";
str += 9;
et.setText(str);
flag = 0;
} else {
str += 9;
et.setText(str);
}
break;
case R.id.equal:
n2 = Double.parseDouble(str);
calculater();
str = "" + r;
et.setText(str);
flag = 1;
break;
case R.id.add:
if (str != "") {
n2 = Double.parseDouble(str);
calculater();
sign = 1;
flag = 1;
}
break;


case R.id.substract:
if (str != "") {
n2 = Double.parseDouble(str);
calculater();
sign = 2;
flag = 1;
}
break;
case R.id.multiply:
if (str != "") {
n2 = Double.parseDouble(str);
calculater();
sign = 3;
flag = 1;
}
break;
case R.id.divide:
if (str != "") {
n2 = Double.parseDouble(str);
calculater();
sign = 4;
flag = 1;
}
break;
case R.id.point:
if (str == "") {
str += ".";
et.setText(str);
} else {
int x = 0;
char[] c1 = str.toCharArray();
for (int i = 0; i < c1.length; i++) {
if (c1[i] == '.') {
x++;
}
}
if (x == 0) {
str += ".";
et.setText(str);
}
}
break;
case R.id.delete:
if(str!=""&&str.length()>0){
str=str.substring(0, str.length()-1);
et.setText(str);}
break;
case R.id.plusorminus:
char c = str.charAt(0);
if (c == '-') {
str = str.replace("-", "");
} else {
str = "-" + str;
}
et.setText(str);
break;
case R.id.radicals:
if (str != "") {
double a = Double.parseDouble(str);
str = Math.sqrt(a) + "";
et.setText(str);
}
break;
case R.id.square:
if (str != "") {
double a = Double.parseDouble(str);
str = "" + a * a;
et.setText(str);
}
break;
}
}


public double calculater() {
switch (sign) {
case 0:
r = n2;
break;
case 1:
r = n1 + n2;
break;
case 2:
r = n1 - n2;
break;
case 3:
r = n1 * n2;
break;
case 4:
t1=BigDecimal.valueOf(n1);
t2=BigDecimal.valueOf(n2);
t=t1.divide(t2,15,BigDecimal.ROUND_HALF_UP);
r =t.doubleValue();
break;
}
n1 = r;
sign = 0;
return r;
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}


}