This article shares the specific code for Android to implement a simple calculator for your reference. The specific content is as follows
// Date: 2014/9/26
// First, people's input habit is an infix expression. For ease of calculation, the program converts the infix expression to the suffix expression
////////////////////////////////////////////////////////////////////////////////////////
// The software still exists// 1. The phenomenon of crashing when the input operation number and operator do not match. (For example: only one operand)// 2. Repeat input of two decimal points in a number. (such as 4.5.6)// These two major bugs will be modified in the future
////////////////////////////////////////////////////////////////////////////////////////
// There is only one layout. This will also be considered and improved in the future.// If there are other incomplete areas, please correct them. (╯▽╰)
package ;
import ; //I don't quite understand what it isimport ;
import ;
import ;
import ;
import ;
import ;
import ;
import ; // Show copyright informationimport ; // Iteratorimport ; // Two-way list
public class MainActivity extends Activity {
private EditText content;
private EditText operaline;
private Double first_num = 0.0; // The first operand private Double sec_num = 0.0; // The second operand //Cannot set bool type variable?????? private static int equal_flg = 0; // The status of the equal sign: FALSE means that the equal sign has not been pressed, and TRUE means that the equal sign has been pressed private double negative_mark = 0; // Positive and negative numbers mark LinkedList<String> Infix = new LinkedList<String>(); // parse the content, that is, the linked list that stores the infix expression LinkedList<String> Suffix = new LinkedList<String>(); // Link list that stores suffix expressions LinkedList<Double> Suffix_Num = new LinkedList<Double>(); // Number link list that stores suffix expressions LinkedList<String> OP = new LinkedList<String>(); // 1. As a linked list for temporary storing operators; 2. Operators that store suffix expressions
@Override
protected void onCreate(Bundle savedInstanceState)
{
(savedInstanceState);
setContentView(.activity_main);
// Handle the "c" screen clear button function Button clear = (Button) findViewById();
(new OnClickListener() {
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
content = (EditText) findViewById();
("");
equal_flg = 0;
first_num = 0.0;
sec_num = 0.0;
();
();
Suffix_Num.clear();
("");
(().length());
}
});
// Handle CE to delete the current operation button function Button current_clear = (Button) findViewById(.current_clear);
current_clear.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
content = (EditText) findViewById();
("");
equal_flg = 0;
first_num = 0.0;
sec_num = 0.0;
();
();
Suffix_Num.clear();
}
});
// Handle backspace button function Button back = (Button) findViewById();
(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
content = (EditText) findViewById();
String str = ().toString();
if (().length() != 0)
((0, () - 1));
(().length()); //I don't know what it is for now. If the edit box is empty, there is no need to handle it. Verify whether it will cause an exception to exit }
});
// Consider whether symbolic keys and numeric keys need to be implemented separately // Implement monitoring of the "0123456789.+-*/()" button; while monitoring of the "=" button is performed in the onCreate() method using anonymous internal class method OnClickListener mylistener = new OnClickListener()
{
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Button num_btn = (Button) v;
content = (EditText) findViewById();
// Storage interface calculation formula String content_str = ().toString();
// When there has been an operation, press the "number key" again to clear the last result if((1==equal_flg)/*&&(num_btn.getText().toString().equals("1")
||num_btn.getText().toString().equals("2")
||num_btn.getText().toString().equals("3")
||num_btn.getText().toString().equals("4")
||num_btn.getText().toString().equals("5")
||num_btn.getText().toString().equals("6")
||num_btn.getText().toString().equals("7")
||num_btn.getText().toString().equals("8")
||num_btn.getText().toString().equals("9")
||num_btn.getText().toString().equals("0"))*/)
{
("0");
(().length());
(,"It's really executed!", Toast.LENGTH_LONG).show();
equal_flg=0;
}
// Repeat the processing of inputting operators, brackets or "." if(("+".equals(content_str.substring(content_str.length()-1,content_str.length()))
||"-".equals(content_str.substring(content_str.length()-1,content_str.length()))
||"*".equals(content_str.substring(content_str.length()-1,content_str.length()))
||"/".equals(content_str.substring(content_str.length()-1,content_str.length()))
||".".equals(content_str.substring(content_str.length()-1,content_str.length())))&&((num_btn.getText().toString().equals("+")
||num_btn.getText().toString().equals("-")
||num_btn.getText().toString().equals("*")
||num_btn.getText().toString().equals("/")
||num_btn.getText().toString().equals("."))))
{
content_str=content_str.substring(0, content_str.length()-1);
//(,"Did your hand shake?", Toast.LENGTH_LONG).show(); }
// Repeat the processing of pressing "." /*if(num_btn.getText().toString().equals("."))
{
// If the interface only has numbers, change the symbol of the current number
if("0"!=content_str)
{
judge_str = turn_mark(judge_str);
(judge_str);
(().length());
// (,"GET", Toast.LENGTH_LONG).show();
}
}*/
// No splicing is achieved // The current data is 0, and the next time the input is a non-0 number or bracket if("0".equals(().toString())
&&!(num_btn.getText().toString().equals("+"))
&&!(num_btn.getText().toString().equals("-"))
&&!(num_btn.getText().toString().equals("*"))
&&!(num_btn.getText().toString().equals("/"))
&&!(num_btn.getText().toString().equals(".")))
{
// Is cast testing dangerous? ? ? ? ? ? content_str = (String) num_btn.getText();
//(,num_btn.getText(), Toast.LENGTH_LONG).show();
}
// Realize splicing // The current data is 0 and the next time it is entered is an operator or dot number else
{
content_str += num_btn.getText();
//(,content_str, Toast.LENGTH_LONG).show();
}
(content_str);
(().length());
}
};
// No special processing required for numeric and symbol buttons Button num1 = (Button) findViewById(.num_1);
(mylistener);
Button num2 = (Button) findViewById(.num_2);
(mylistener);
Button num3 = (Button) findViewById(.num_3);
(mylistener);
Button num4 = (Button) findViewById(.num_4);
(mylistener);
Button num5 = (Button) findViewById(.num_5);
(mylistener);
Button num6 = (Button) findViewById(.num_6);
(mylistener);
Button num7 = (Button) findViewById(.num_7);
(mylistener);
Button num8 = (Button) findViewById(.num_8);
(mylistener);
Button num9 = (Button) findViewById(.num_9);
(mylistener);
Button point = (Button) findViewById();
(mylistener);
Button left = (Button) findViewById();
(mylistener);
Button right = (Button) findViewById();
(mylistener);
Button plus = (Button) findViewById();
(mylistener);
Button subtract = (Button) findViewById();
(mylistener);
Button multiply = (Button) findViewById();
(mylistener);
Button divide = (Button) findViewById();
(mylistener);
// Processing of button 0 Button num0 = (Button) findViewById(.num_0);
(new OnClickListener()
{
@Override
public void onClick(View v)
{
content = (EditText) findViewById();
// The value in the current edit box is 0 if ("0".equals(().toString())||""== ().toString())
{
("0");
}
// There is already non-0 data in the edit box else
{
String str = ().toString();
str += "0";
(str);
}
(().length());
// (,"GET", Toast.LENGTH_LONG).show();
}
});
// Handling of "-/+" Button mark_sign = (Button) findViewById(.mark_sign);
mark_sign.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
content = (EditText) findViewById();
String judge_str = ().toString();
// If the interface only has numbers, change the symbol of the current number if("0"!=judge_str&&((-1==judge_str.indexOf("+"))
||(-1==judge_str.indexOf("-")))
||(-1==judge_str.indexOf("*"))
||(-1==judge_str.indexOf("/"))
||(-1==judge_str.indexOf("("))
||(-1==judge_str.indexOf(")")))
{
judge_str = turn_mark(judge_str);
(judge_str);
(().length());
// (,"GET", Toast.LENGTH_LONG).show();
}
}
});
// Implement the function of "=" button Button equal = (Button) findViewById();
(new OnClickListener()
{
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
content = (EditText) findViewById();
operaline = (EditText) findViewById();
// str_Infix is the infix expression to be converted String str_Infix = ().toString();
// Friendly interface prompt processing String equate = str_Infix;
equate += "=";
(equate);
(().length());
// Call Analysis function to parse content (str_Infix);
(Infix);
// So far, the infix expression has been stored in the Infix linked list
Iterator<String> it = ();
while (())
{
String tmp_str = ();
if (isNum(tmp_str))
{
// If it is a number or a decimal point, it will be directly entered into the Suffix linked list; (tmp_str);
}
// If it is not a number or a decimal point; else
{
int OP_level = () ? 0 : getLevel(());
// tmp_str is higher than the top operator of OP and enters OP if (getLevel(tmp_str) > OP_level)
{
(tmp_str);
}
// tmp_str is lower than the top operator of OP else
{
// tmp_str is ")", then the OP is out until it encounters "(" if (getLevel(tmp_str) == -1)
{
String temp_OP = ();
while (getLevel(temp_OP) != -2) {
(temp_OP);
temp_OP = ();
}
}
// tmp_str is "(", then it will be directly entered into the OP else if (getLevel(tmp_str) == -2)
{
(tmp_str);
}
// tmp_str is lower than OP_level and is not "(" ")", // Then the OP is out of the stack until the OP is empty or tmp_str is higher than the OP_level else
{
String str2 = ();
while (getLevel(str2) >= OP_level)
{
(str2);
if (())
{
break;
}
str2 = ();
}
(tmp_str);
}
}
}
}
();// Clear the Infix link list // The remaining elements in the OP come out of the OP and enter Suffix while (!())
{
(());
}
(Suffix);
// So far, the infix expressions have been converted into the suffix expression Suffix
// Calculation process of suffix expressions? ? ? When no operand is specified, the default is 0 while (!(()))
{
String count_str = ();
if (isOP(count_str))
{
char compare_ch = count_str.charAt(0);
first_num = Suffix_Num.removeLast();
sec_num = Suffix_Num.removeLast();
switch (compare_ch) {
case '*':
Suffix_Num.addLast(sec_num * first_num);
break;
case '/':
// Test the order of divisors and divisors if (first_num != 0)
{
Suffix_Num.addLast(sec_num / first_num);
break;
} else
{
content = (EditText) findViewById();
// ????? Cannot edit the box anymore, set the prompt ("∞");
(().length());
}
case '+':
Suffix_Num.addLast(sec_num + first_num);
break;
case '-':
Suffix_Num.addLast(sec_num - first_num);
break;
}
}
else
{
Suffix_Num.addLast((count_str));
}
}
// So far, the result obtained is in the Suffix_Num list
// The logic of this part is result. Stores the data retrieved from the Suffix_Num list, and displays it on the interface after processing. Double result=Suffix_Num.removeFirst();
String res_str=(result);
if("0".equals(res_str.substring(res_str.length()-1,res_str.length())))
{
if(".".equals(res_str.substring(res_str.length()-2,res_str.length()-1)))
{
res_str=res_str.substring(0,res_str.length()-2);
//(,res_str, Toast.LENGTH_LONG).show();
};
};
(res_str);
(().length());
equal_flg = 1;
if("-".equals(res_str.substring(0,1)))
res_str=turn_mark(res_str);
}
});
// Clear operands???????android has an automatic release mechanism? first_num = 0.0;
sec_num = 0.0;
();
();
Suffix_Num.clear();
}
// Custom isNum() method to detect whether the element is numeric public boolean isNum(String str) {
int num = 0;
for (int i = 0; i < (); i++) {
String strr = (i, i + 1);
if (("0") || ("1") || ("2")
|| ("3") || ("4") || ("5")
|| ("6") || ("7") || ("8")
|| ("9") || ("."))
num = num + 1;
}
if (num == ())
return true;
else
return false;
}
// Custom isOP() method to detect whether the elements of the Suffix list are operators public boolean isOP(String strr) {
if (("+") || ("-") || ("*")
|| ("/"))
return true;
else
return false;
}
// Define the operator's level public int getLevel(String str) {
if (("*") || ("/")) {
return 2;
} else if (("+") || ("-")) {
return 1;
} else if (("(")) {
return -2;
} else if ((")")) {
return -1;
} else {
return 0;
}
}
// Change the positive and negative signs public String turn_mark(String str)
{
String temp = "(";
temp += "-";
temp += str;
temp += ")";
str = temp;
return str;
}
// Implement the content of the edit box separately stored by numbers and operators public void Analysis(String str) {
String sub = "";
for (int i = 0; i < (); i++)
{
// Use substring to traverse the array to be parsed String strr = (i, i + 1);
if (isNum(strr))
{
sub += strr;
}
else
{
if (sub != "")
{
(sub); // First sub into Infix sub = ""; // Clear the sub }
(strr); // "+-*/" "(" ")" will enter the Infix table directly }
}
// ? ? ? ? ? Test whether the IF below for is because the loop cannot determine the last number if (isNum((() - 1))) {
(sub); // First sub into Infix sub = ""; // Clear the sub }
}
@Override
public boolean onCreateOptionsMenu(Menu menu)
{
/*
* // Inflate the menu; this adds items to the action bar if it is
* present. getMenuInflater().inflate(, menu);
*/
(0, 1, 1, "quit");
(0, 2, 2, "about");
(0, 3, 3, "help");
return (menu);
/* return true; */
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// TODO Auto-generated method stub
//finish();
if (() == 2)
{
// Use Toast to display prompt information (,"Author:Yi Contact:cdch@", Toast.LENGTH_LONG).show();
}
if (() == 3)
{
// Use Toast to display prompt information (,"Applicable to general arithmetic operations!", Toast.LENGTH_LONG).show();
}
return (item);
};
}
The above is all the content of this article. I hope it will be helpful to everyone's study and I hope everyone will support me more.