Java programming processing arithmetic (including parentheses)

Package com.malakana.cal;

Import Android.annotation.SuppressLint;

Import java.util.*;

public class Yunsuan {

Yunsuan (String str1) {

EvaluateExpression (STR1);

}

@SuppressLint ("usevalueof")

public static string EvaluateExpression (String str) {

Char[] A;

int i = 0;

A = Str.tochararray ();

stack<float> OPND = new stack<float> ();

stack<character> optr = new stack<character> ();

Optr.push (' = ');

float number = 0;

int decimalnum = 1;

Boolean integer = false;

Boolean decimal = false;

while (true) {

if (i = = Str.length ())

Break

if (in (a[i]) = =-1) {

Number = number * + (A[i]-48);

Integer = true;

if (decimal)

Decimalnum = Decimalnum * 10;

i++;

} else if (a[i] = = '. ') {

if (decimal)

return "ERROR";

decimal = integer = true;

i++;

} else if (in (A[i]) >-1 && in (A[i]) < 7) {

if (in (a[i]) = = 1 && (i = = 0 | | In (a[i-1]) = = 4))

Opnd.push (new Float (0));

if (integer) {

Opnd.push (New Float (Number/decimalnum));

Number = 0;

Decimalnum = 1;

Integer = decimal = false;

}

Switch (Precede (in (Optr.peek ()), in (A[i]))) {

Case 2:

if (Opnd.empty ())

return "ERROR";

float x = Opnd.pop ();

if (Opnd.empty ())

return "ERROR";

Float y = opnd.pop ();

Char theta = Optr.pop ();

if (in (theta) = = 3 && x = = 0)

return "ERROR";

Opnd.push (New Float (Operate (y, theta, X)));

Break

Case 1:

Optr.pop ();

i++;

Break

Case 0:

Optr.push (New Character (A[i]));

i++;

Break

Case-1:

return "ERROR";

}

}

}

if (Opnd.empty ())

return "ERROR";

Else

Return ("" + Opnd.peek ());

}

public static int in (char t) {

int i = 0;

if (T > && T < 58)

return-1;

Switch (t) {

Case ' + ':

i = 0;

Break

Case '-':

i = 1;

Break

Case ' * ':

i = 2;

Break

Case '/':

i = 3;

Break

Case ' (':

i = 4;

Break

Case ') ':

i = 5;

Break

Case ' = ':

i = 6;

Break

}

return i;

}

public static int precede (int t1, int t2) {

int relationship[][] = {{2, 2, 0, 0, 0, 2, 2},

{2, 2, 0, 0, 0, 2, 2}, {2, 2, 2, 2, 0, 2, 2},

{2, 2, 2, 2, 0, 2, 2}, {0, 0, 0, 0, 0, 1,-1},

{2, 2, 2, 2,-1, 2, 2}, {0, 0, 0, 0, 0,-1, 1}};

return RELATIONSHIP[T1][T2];

}

public static float Operate (float A, char theta, float b) {

float i = 0;

Switch (theta) {

Case ' + ':

i = a + b;

Break

Case '-':

i = a-B;

Break

Case ' * ':

i = a * b;

Break

Case '/':

i = A/b;

Break

}

return i;

}

public static void Main (string[] args) {

New Yunsuan (NULL);

}

}

Java programming processing arithmetic (including parentheses)