package com.example.calculator1;

import android.app.Activity;
import android.os.Bundle;
import android.view.*;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity implements View.OnClickListener{
	 	private Button btn_0;//0数字按钮
	    private Button btn_1;//1数字按钮
	    private Button btn_2;//2数字按钮
	    private Button btn_3;//3数字按钮
	    private Button btn_4;//4数字按钮
	    private Button btn_5;//5数字按钮
	    private Button btn_6;//6数字按钮
	    private Button btn_7;//7数字按钮
	    private Button btn_8;//8数字按钮
	    private Button btn_9;//9数字按钮
	    private Button btn_clear;//clear按钮
	    private Button btn_point;//小数点按钮
	    private Button btn_plus;//+按钮
	    private Button btn_minus;//-按钮
	    private Button btn_multply;//*按钮
	    private Button btn_divide;//除号按钮
	    private Button btn_equal;//=按钮
	    private EditText editText;

	    boolean clear_flag;//清空标识

	    @Override
	    protected void onCreate(Bundle savedInstanceState) {
	        super.onCreate(savedInstanceState);
	        setContentView(R.layout.activity_main);

	        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_clear = (Button) findViewById(R.id.btn_clear);
	        btn_point = (Button) findViewById(R.id.btn_point);
	        btn_plus = (Button) findViewById(R.id.btn_plus);
	        btn_minus = (Button) findViewById(R.id.btn_minus);
	        btn_multply = (Button) findViewById(R.id.btn_multply);
	        btn_divide = (Button) findViewById(R.id.btn_divide);
	        btn_equal = (Button) findViewById(R.id.btn_equal);
	        editText = (EditText) findViewById(R.id.et_input);
	        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_clear.setOnClickListener(this);
	        btn_point.setOnClickListener(this);
	        btn_plus.setOnClickListener(this);
	        btn_minus.setOnClickListener(this);
	        btn_multply.setOnClickListener(this);
	        btn_divide.setOnClickListener(this);
	        btn_equal.setOnClickListener(this);
	        editText.setFocusable(false);
	    }

	    @Override
	    public void onClick(View view) {
	        String input = editText.getText().toString();
	        switch (view.getId()){
	            case R.id.btn_0:
	            case R.id.btn_1:
	            case R.id.btn_2:
	            case R.id.btn_3:
	            case R.id.btn_4:
	            case R.id.btn_5:
	            case R.id.btn_6:
	            case R.id.btn_7:
	            case R.id.btn_8:
	            case R.id.btn_9:
	            case R.id.btn_point:
	                if(clear_flag){
	                    clear_flag = false;
	                    editText.setText("");
	                }
	                editText.setText(input + ((Button)view).getText());
	                break;
	            case R.id.btn_plus:
	            case R.id.btn_minus:
	            case R.id.btn_multply:
	            case R.id.btn_divide:
	                if(clear_flag){
	                    clear_flag = false;
	                    input = "";
	                    editText.setText("");
	                }
	                editText.setText(input + " " + ((Button)view).getText() + " ");
	                break;
	            case R.id.btn_clear:
	                clear_flag = false;
	                input = "";
	                editText.setText("");
	                break;
	            case R.id.btn_equal:
	                getResult();
	                break;
	        }
	    }

	    //运算结果
	    private void getResult(){
	        String exp = editText.getText().toString();
	        if(exp==null||exp.equals(""))
	            return;
	        if(!exp.contains(" "))
	            return;
	        if(clear_flag){
	            clear_flag = false;
	            return;
	        }
	        clear_flag = true;
	        double result = 0;
	        //运算符前的数字
	        String s1 = exp.substring(0,exp.indexOf(" "));
	        //运算符
	        String op = exp.substring(exp.indexOf(" ")+1,exp.indexOf(" ")+2);
	        //运算符后的数字
	        String s2 = exp.substring(exp.indexOf(" ")+3);

	        if(!s1.equals("")&&!s2.equals("")) {
	            double d1 = Double.parseDouble(s1);
	            double d2 = Double.parseDouble(s2);
	            if (op.equals("+")) {
	                result = d1 + d2;
	            } else if (op.equals("-")) {
	                result = d1 - d2;
	            } else if (op.equals("*")) {
	                result = d1 * d2;
	            } else if (op.equals("/")) {
	                if (d2 == 0)
	                    result = 0;
	                else
	                    result = d1 / d2;
	            }
	            if (!s1.contains(".") && !s2.contains(".") && !op.equals("/")) {
	                int r = (int) result;
	                editText.setText(r + "");
	            } else
	                editText.setText(result + "");
	        	}else if(!s1.equals("") && s2.equals("")){
	        		editText.setText(exp);
	        	}else if(s1.equals("") && !s2.equals("")){
	        		double d2 = Double.parseDouble(s2);
	        		if (op.equals("+")) {
	        			result = 0 + d2;
	        		} else if (op.equals("-")) {
	        			result = 0 - d2;
	        		} else if (op.equals("*")) {
	        			result = 0;
	        		} else if (op.equals("/")) {
	                    result = 0;
	        		}
	        		if (!s1.contains(".") && !s2.contains(".")) {
	        			int r = (int) result;
	        				editText.setText(r + "");
	        		} else
	        			editText.setText(result + "");
	        	}else {
	        		editText.setText("");
	        	}
	    }
}