步骤：
1：输入一个数储存在变量num1中
2：选择 + - * /任意一个运算符
3：输入另一个数储存在变量num2中
4：并把运算结果保存到变量result中并显示
//如果被除数为0则结果默认显示为0
//在把String类型转化成double时有可能出现NumberFormatException异常，tyr,catch一下就可以了
/activity_main.xml效果图如下/
/activity_main.xml代码如下/
</RelativeLayout>
/MainActivity.xml代码如下/
public class MainActivity extends AppCompatActivity {
private TextView DisplayBox;
private Button Number0, Number1,Number2,Number3,Number4,Number5,Number6,Number7,Number8,Number9;
private Button Add,Subtract,Multiply,Divide,Equal;// + - * / =
private Button Reset ,Point;
double num1 = 0,num2 = 0;//第一次输入的数和第二次输入的数
double result = 0;//存放运算结果
int Operator;//用于判断是那个运算符
//private String str1,str2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
DisplayBox = (TextView) findViewById(R.id.Show);
Number0 = (Button) findViewById(R.id.Number0);
Number1 = (Button) findViewById(R.id.Number1);
Number2 = (Button) findViewById(R.id.Number2);
Number3 = (Button) findViewById(R.id.Number3);
Number4 = (Button) findViewById(R.id.Number4);
Number5 = (Button) findViewById(R.id.Number5);
Number6 = (Button) findViewById(R.id.Number6);
Number7 = (Button) findViewById(R.id.Number7);
Number8 = (Button) findViewById(R.id.Number8);
Number9 = (Button) findViewById(R.id.Number9);
Add = (Button) findViewById(R.id.Add);
Subtract = (Button) findViewById(R.id.Subtract);
Multiply = (Button) findViewById(R.id.Multiply);
Divide = (Button) findViewById(R.id.Divide);
Equal = (Button) findViewById(R.id.Equal);
Reset = (Button) findViewById(R.id.Clear);
Point = (Button) findViewById(R.id.Point);
SetListen();
}
public void SetListen(){
OnClick onClick = new OnClick();
Number0.setOnClickListener(onClick);
Number1.setOnClickListener(onClick);
Number2.setOnClickListener(onClick);
Number3.setOnClickListener(onClick);
Number4.setOnClickListener(onClick);
Number5.setOnClickListener(onClick);
Number6.setOnClickListener(onClick);
Number7.setOnClickListener(onClick);
Number8.setOnClickListener(onClick);
Number9.setOnClickListener(onClick);
Point.setOnClickListener(onClick);
Add.setOnClickListener(onClick);
Subtract.setOnClickListener(onClick);
Multiply.setOnClickListener(onClick);
Divide.setOnClickListener(onClick);
Equal.setOnClickListener(onClick);
Reset.setOnClickListener(onClick);
}
class OnClick implements View.OnClickListener{
@Override
public void onClick(View v) {
switch (v.getId())
{
case R.id.Clear:
DisplayBox.setText(null);
break;
case R.id.Number0:
String str0 = DisplayBox.getText().toString().trim();
str0 += "0";
DisplayBox.setText(str0);
break;
case R.id.Number1:
String str1 = DisplayBox.getText().toString().trim();
str1 += "1";
DisplayBox.setText(str1);
break;
case R.id.Number2:
String str2 = DisplayBox.getText().toString().trim();
str2 += "2";
DisplayBox.setText(str2);
break;
case R.id.Number3:
String str3 = DisplayBox.getText().toString().trim();
str3 += "3";
DisplayBox.setText(str3);
break;
case R.id.Number4:
String str4 = DisplayBox.getText().toString().trim();
str4 += "4";
DisplayBox.setText(str4);
break;
case R.id.Number5:
String str5 = DisplayBox.getText().toString().trim();
str5 += "5";
DisplayBox.setText(str5);
break;
case R.id.Number6:
String str6 = DisplayBox.getText().toString().trim();
str6 += "6";
DisplayBox.setText(str6);
break;
case R.id.Number7:
String str7 = DisplayBox.getText().toString().trim();
str7 += "7";
DisplayBox.setText(str7);
break;
case R.id.Number8:
String str8 = DisplayBox.getText().toString().trim();
str8 += "8";
DisplayBox.setText(str8);
break;
case R.id.Number9:
String str9 = DisplayBox.getText().toString().trim();
str9 += "9";
DisplayBox.setText(str9);
break;
case R.id.Point:
String point = DisplayBox.getText().toString().trim();
point += ".";
DisplayBox.setText(point);
break;
case R.id.Add:
String add = DisplayBox.getText().toString().trim();
if (add.equals(null))
{
return;
}
try {
num1 = Double.valueOf(add);
}catch (NumberFormatException e)
{
e.printStackTrace();
}
add += "+";
DisplayBox.setText(null);
Operator = 1;
break;
case R.id.Subtract:
String subtract = DisplayBox.getText().toString().trim();
if (subtract.equals(null))
{
return;
}
try {
num1 = Double.valueOf(subtract);
}catch (NumberFormatException e)
{
e.printStackTrace();
}
subtract += "-";
DisplayBox.setText(null);
Operator = 2;
break;
case R.id.Multiply:
String multiply = DisplayBox.getText().toString().trim();
if (multiply.equals(null))
{
return;
}
try {
num1 = Double.valueOf(multiply);
}catch (NumberFormatException e)
{
e.printStackTrace();
}
multiply += "*";
DisplayBox.setText(null);
Operator = 3;
break;
case R.id.Divide:
String divide = DisplayBox.getText().toString().trim();
if (divide.equals(null))
{
return;
}
try {
num1 = Double.valueOf(divide);
}catch (NumberFormatException e)
{
e.printStackTrace();
}
divide += "/";
DisplayBox.setText(null);
Operator = 4;
break;
case R.id.Equal:
String equal = DisplayBox.getText().toString().trim();
try {
num2 = Double.valueOf(equal);
}catch (NumberFormatException e)
{
e.printStackTrace();
}
DisplayBox.setText(equal);
switch (Operator)
{
case 1:
result = num1 + num2;
DisplayBox.setText(num1 + "+" + num2 + "=" +result);
break;
case 2:
result = num1 - num2;
DisplayBox.setText(num1 + "-" + num2 + "=" +result);
break;
case 3:
result = num1 * num2;
DisplayBox.setText(num1 + "*" + num2 + "=" +result);
break;
case 4:
if (num2 == 0)
{
DisplayBox.setText("0");
}
else {
result = num1 / num2;
DisplayBox.setText(num1 + "/" + num2 + "=" + result);
}
break;
}
break;
default:
result = 0;
break;
}
}
}
}
/效果图/
