问题
I have created a simple calculator that calculates two inputs (ex. 2 + 2 = 4). What I want to do now is to make the app to calculate multiple operations like (ex. 2 + 2 * 4 - 1 = 15). Can someone help me with my code? Here is my code.
public class MainActivity extends Activity {
public String str ="";
Character op = 'q';
int i,num,numtemp;
EditText showResult;
String displayStr = "";
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
this.getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_STATE_ALWAYS_HIDDEN);
showResult = (EditText)findViewById(R.id.result_id);
}
public void btn1Clicked(View v){
insert(1);
}
public void btn2Clicked(View v){
insert(2);
}
public void btn3Clicked(View v){
insert(3);
}
public void btn4Clicked(View v){
insert(4);
}
public void btn5Clicked(View v){
insert(5);
}
public void btn6Clicked(View v){
insert(6);
}
public void btn7Clicked(View v){
insert(7);
}
public void btn8Clicked(View v){
insert(8);
}
public void btn9Clicked(View v){
insert(9);
}
public void btn0Clicked(View v){
insert(0);
}
public void btnplusClicked(View v){
perform();
op = '+';
displayStr += "+";
}
public void btnminusClicked(View v){
perform();
op = '-';
displayStr += "-";
}
public void btndivideClicked(View v){
perform();
op = '/';
displayStr += "/";
}
public void btnmultiClicked(View v){
perform();
op = '*';
displayStr += "*";
}
public void btnequalClicked(View v){
calculate();
}
public void btnclearClicked(View v){
reset();
}
private void reset() {
// TODO Auto-generated method stub
str ="";
op ='q';
num = 0;
numtemp = 0;
displayStr = "";
showResult.setText("");
}
private void insert(int j) {
// TODO Auto-generated method stub
str = str+Integer.toString(j);
num = Integer.valueOf(str).intValue();
displayStr += Integer.toString(j);
showResult.setText(displayStr);
}
private void perform() {
// TODO Auto-generated method stub
str = "";
numtemp = num;
}
private void calculate() {
// TODO Auto-generated method stub
String first=String.valueOf(numtemp);
String second=String.valueOf(num);
if(op == '+')
num = numtemp+num;
else if(op == '-')
num = numtemp-num;
else if(op == '/')
num = numtemp/num;
else if(op == '*')
num = numtemp*num;
showResult.setText(first+op+second+"="+num);
}
}
回答1:
Use some stack operations.
May be the below links will helpful to you.
http://innovativenetsolutions.com/2013/01/calculator-app/
http://www.androiddom.com/2011/04/creating-android-calculator-tutorial.html
回答2:
You need to use stack operations for performing this kind of arithmetic evaluations programatically. Please check this link Arithmetic Operations using Stack for the algorithm you need to write.
来源：https://stackoverflow.com/questions/22704849/simple-calculator-with-multiple-operations-android