Android实验2:简易计算器

1.     完成一个计算器的设计,可以以手机自带的计算器为参考。设计过程中,注意考虑界面的美观性,不同机型的适应性,以及功能的完备性。

2.     注意结合Activity的生命周期,考虑不同情况下计算器的界面状态。

3.      如有余力,可以考虑实现一个高精度科学计算型的计算器。


activity_main.xml




    
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MainActivity.java


import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.Arrays;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    Button btn_0;
    Button btn_1;
    Button btn_2;
    Button btn_3;
    Button btn_4;
    Button btn_5;
    Button btn_6;
    Button btn_7;
    Button btn_8;
    Button btn_9;
    Button btn_point;
    Button btn_clear;
    Button btn_del;
    Button btn_plus;
    Button btn_minus;
    Button btn_multiply;
    Button btn_divide;
    Button btn_equal;
    Button btn_left;
    Button btn_right;
    private TextView et_input;
    private StringBuilder pending = new StringBuilder();

    private void initView() {
        btn_0 = (Button) findViewById(R.id.btn_0);
        btn_1 = (Button) findViewById(R.id.btn_1);
        btn_2 = (Button) findViewById(R.id.btn_2);
        btn_3 = (Button) findViewById(R.id.btn_3);
        btn_4 = (Button) findViewById(R.id.btn_4);
        btn_5 = (Button) findViewById(R.id.btn_5);
        btn_6 = (Button) findViewById(R.id.btn_6);
        btn_7 = (Button) findViewById(R.id.btn_7);
        btn_8 = (Button) findViewById(R.id.btn_8);
        btn_9 = (Button) findViewById(R.id.btn_9);
        btn_point = (Button) findViewById(R.id.btn_point);
        btn_clear = (Button) findViewById(R.id.btn_clear);
        btn_del = (Button) findViewById(R.id.btn_del);
        btn_plus = (Button) findViewById(R.id.btn_plus);
        btn_minus = (Button) findViewById(R.id.btn_minus);
        btn_multiply = (Button) findViewById(R.id.btn_multiply);
        btn_divide = (Button) findViewById(R.id.btn_divide);
        btn_equal = (Button) findViewById(R.id.btn_equal);
        et_input = (TextView) findViewById(R.id.et_input);
        btn_left = (Button) findViewById(R.id.btn_left);
        btn_right = (Button) findViewById(R.id.btn_right);

        btn_0.setOnClickListener(this);
        btn_1.setOnClickListener(this);
        btn_2.setOnClickListener(this);
        btn_3.setOnClickListener(this);
        btn_4.setOnClickListener(this);
        btn_5.setOnClickListener(this);
        btn_6.setOnClickListener(this);
        btn_7.setOnClickListener(this);
        btn_8.setOnClickListener(this);
        btn_9.setOnClickListener(this);
        btn_point.setOnClickListener(this);
        btn_plus.setOnClickListener(this);
        btn_equal.setOnClickListener(this);
        btn_minus.setOnClickListener(this);
        btn_multiply.setOnClickListener(this);
        btn_del.setOnClickListener(this);
        btn_divide.setOnClickListener(this);
        btn_clear.setOnClickListener(this);
        btn_divide.setOnClickListener(this);
        btn_left.setOnClickListener(this);
        btn_right.setOnClickListener(this);
    }
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        initView();
    }

    public void onClick(View v) {
        int last = 0;
        if(pending.length()!=0)
        {
            last = pending.codePointAt(pending.length()-1);
        }
        switch (v.getId())
        {
            case R.id.btn_0:
                pending = pending.append("0");
                et_input.setText(pending);
                break;
            case R.id.btn_1:
                pending = pending.append("1");
                et_input.setText(pending);
                break;
            case R.id.btn_2:
                pending = pending.append("2");
                et_input.setText(pending);
                break;
            case R.id.btn_3:
                pending = pending.append("3");
                et_input.setText(pending);
                break;
            case R.id.btn_4:
                pending = pending.append("4");
                et_input.setText(pending);
                break;
            case R.id.btn_5:
                pending = pending.append("5");
                et_input.setText(pending);
                break;
            case R.id.btn_6:
                pending = pending.append("6");
                et_input.setText(pending);
                break;
            case R.id.btn_7:
                pending = pending.append("7");
                et_input.setText(pending);
                break;
            case R.id.btn_8:
                pending = pending.append("8");
                et_input.setText(pending);
                break;
            case R.id.btn_9:
                pending = pending.append("9");
                et_input.setText(pending);
                break;
            case R.id.btn_plus:
                pending = pending.append("+");
                et_input.setText(pending);
                break;
            case R.id.btn_minus:
                pending = pending.append("-");
                et_input.setText(pending);
                break;
            case R.id.btn_multiply:
                pending = pending.append("*");
                et_input.setText(pending);
                break;
            case R.id.btn_divide:
                pending = pending.append("/");
                et_input.setText(pending);
                break;
            case R.id.btn_point:
                if (judje1())
                {
                    pending = pending.append(".");
                    et_input.setText(pending);
                }
                break;
            case R.id.btn_right:// )右括号
                if((last>='0' &&last<='9'||last==')')&&judje2()==1)
                {
                    pending = pending.append(")");
                    et_input.setText(pending);
                }
                break;
            case R.id.btn_left:// (左括号
                if((last!='(')||(last<='0' &&last>='9'))
                {
                    pending = pending.append("(");
                    et_input.setText(pending);
                }
                break;

            case R.id.btn_del: //删除
                if (pending.length() != 0)
                {
                    pending = pending.delete(pending.length() - 1, pending.length());
                    et_input.setText(pending);
                }
                break;
            case R.id.btn_clear: //清空
                pending = pending.delete(0, pending.length());
                et_input.setText(pending);
                break;
            case R.id.btn_equal: // =等于
                if ((pending.length() > 1))
                {
                    Function inf = new Function();
                    String jieguo;
                    try
                    {
                        String a = inf.toSuffix(pending);
                        jieguo = inf.dealEquation(a);

                    }
                    catch (Exception ex)
                    {
                        jieguo = "出错";
                    }
                    et_input.setText(pending + "=" + jieguo);
                    pending = pending.delete(0, pending.length());
                    if (Character.isDigit(jieguo.charAt(0)))
                    {
                        pending = pending.append(jieguo);
                    }
                }
                break;
            default:
                break;
        }
    }

    private boolean judje1() {
        String a = "+-*/.";
        int[] b = new int[a.length()];
        int max;
        for (int i = 0; i < a.length(); i++)
        {
            String c = "" + a.charAt(i);
            b[i] = pending.lastIndexOf(c);
        }
        Arrays.sort(b);
        if (b[a.length() - 1] == -1)
        {
            max = 0;
        }
        else
        {
            max = b[a.length() - 1];
        }
        if (pending.indexOf(".", max) == -1)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
    private int judje2(){
        int a=0,b=0;
        for(int i = 0 ; i < pending.length() ;i++)
        {
            if(pending.charAt(i)=='(' )
            {
                a++;
            }
            if(pending.charAt(i)==')' )
            {
                b++;
            }
        }
        if(a == b)
            return 0;
        if(a > b)
            return 1;
        return 2;
    }
}

Function.java


import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.lang.*;


public class Function {

    private static final Map basic =new HashMap();
    static {
        basic.put('-',1);
        basic.put('+', 1);
        basic.put('*', 2);
        basic.put('/', 2);
        basic.put('(', 0);
    }

    public String toSuffix(StringBuilder infix){
        List queue = new ArrayList();
        List stack = new ArrayList();

        char[] charArr = infix.substring(0,infix.length()).trim().toCharArray();
        String standard = "*/+-()";
        char ch = '&';
        int len = 0;
        for (int i = 0; i < charArr.length; i++)
        {
            ch = charArr[i];
            if(Character.isDigit(ch))
            {
                len++;
            }
            else if(ch == '.')
            {
                len++;
            }
            else if(standard.indexOf(ch) != -1)
            {
                if(len > 0)
                {
                    queue.add(String.valueOf(Arrays.copyOfRange(charArr, i - len, i)));
                    len = 0;
                }
                if(ch == '(')
                {
                    stack.add(ch);
                    continue;
                }
                if (!stack.isEmpty())
                {
                    int size = stack.size() - 1;
                    boolean flag = false;
                    while (size >= 0 && ch == ')' && stack.get(size) != '(')
                    {
                        queue.add(String.valueOf(stack.remove(size)));
                        size--;
                        flag = true;
                    }
                    if(ch==')'&&stack.get(size) == '(')
                    {
                        flag = true;
                    }
                    while (size >= 0 && !flag && basic.get(stack.get(size)) >= basic.get(ch))
                    {
                        queue.add(String.valueOf(stack.remove(size)));
                        size--;
                    }
                }
                if(ch != ')')
                {
                    stack.add(ch);
                }
                else
                {
                    stack.remove(stack.size() - 1);
                }
            }
            if(i == charArr.length - 1)
            {
                if(len > 0)
                {
                    queue.add(String.valueOf(Arrays.copyOfRange(charArr, i - len+1, i+1)));
                }
                int size = stack.size() - 1;
                while (size >= 0)
                {
                    queue.add(String.valueOf(stack.remove(size)));
                    size--;
                }
            }
        }
        String a = queue.toString();
        return a.substring(1,a.length()-1);
    }

    public String dealEquation(String equation){

        String [] arr = equation.split(", ");
        List list = new ArrayList();

        for (int i = 0; i < arr.length; i++)
        {
            int size = list.size();
            switch (arr[i])
            {
                case "+": double a = Double.parseDouble(list.remove(size-2))+ Double.parseDouble(list.remove(size-2)); list.add(String.valueOf(a));     break;
                case "-": double b = Double.parseDouble(list.remove(size-2))- Double.parseDouble(list.remove(size-2)); list.add(String.valueOf(b));     break;
                case "*": double c = Double.parseDouble(list.remove(size-2))* Double.parseDouble(list.remove(size-2)); list.add(String.valueOf(c));     break;
                case "/": double d = Double.parseDouble(list.remove(size-2))/ Double.parseDouble(list.remove(size-2)); list.add(String.valueOf(d));       break;
                default: list.add(arr[i]);     break;
            }
        }
        return list.size() == 1 ? list.get(0) : "运算失败" ;
    }
}



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