Android实现简易计算器（可以实现连续计算）

package com.example.calculator;

import android.content.Intent;
import android.support.v7.app.ActionBar;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageButton;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity implements View.OnClickListener{

 getResult2 result2 = new getResult2();


 Button button0;
 Button button1;
 Button button2;
 Button button3;
 Button button4;
 Button button5;
 Button button6;
 Button button7;
 Button button8;
 Button button9;
 Button button_point; //小数点
 Button button_clear; //清空


 //2个imageButton
 Button button_plus;
 Button button_minus;
 Button button_mutiply;
 Button button_divide;
 ImageButton button_equal; //等于
 ImageButton button_delete; //删除（退格）

 EditText edit_input; //输入框
 EditText editText2;

 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_main);
 ActionBar actiOnBar= getSupportActionBar();
 if (actionBar != null) {
 actionBar.hide();
 }
 ImageButton imageButton1 = (ImageButton) findViewById(R.id.title_imageButton1);
 imageButton1.setOnClickListener(new View.OnClickListener() {
 @Override
 public void onClick(View v) {
 Intent intent = new Intent(MainActivity.this, SetActivity.class);
 startActivity(intent);
 }
 });


 //实例化按钮
 button0 = (Button) findViewById(R.id.button0);
 button1 = (Button) findViewById(R.id.button1);
 button2 = (Button) findViewById(R.id.button2);
 button3 = (Button) findViewById(R.id.button3);
 button4 = (Button) findViewById(R.id.button4);
 button5 = (Button) findViewById(R.id.button5);
 button6 = (Button) findViewById(R.id.button6);
 button7 = (Button) findViewById(R.id.button7);
 button8 = (Button) findViewById(R.id.button8);
 button9 = (Button) findViewById(R.id.button9);
 button_point = (Button) findViewById(R.id.button_point);
 button_clear = (Button) findViewById(R.id.button_clear);
 button_plus = (Button) findViewById(R.id.button_plus);
 button_minus = (Button) findViewById(R.id.button_minus);
 button_mutiply = (Button) findViewById(R.id.button_mutiply);
 button_divide = (Button) findViewById(R.id.button_divide);
 button_equal = (ImageButton) findViewById(R.id.button_equal);
 button_delete = (ImageButton) findViewById(R.id.button_delete);
 edit_input = (EditText) findViewById(R.id.main_ediText);
 editText2 = (EditText) findViewById(R.id.edtiText2);

 //设置点击事件
 button0.setOnClickListener((View.OnClickListener) this);
 button1.setOnClickListener((View.OnClickListener) this);
 button2.setOnClickListener((View.OnClickListener) this);
 button3.setOnClickListener((View.OnClickListener) this);
 button4.setOnClickListener((View.OnClickListener) this);
 button5.setOnClickListener((View.OnClickListener) this);
 button6.setOnClickListener((View.OnClickListener) this);
 button7.setOnClickListener((View.OnClickListener) this);
 button8.setOnClickListener((View.OnClickListener) this);
 button9.setOnClickListener((View.OnClickListener) this);
 button_point.setOnClickListener((View.OnClickListener) this);
 button_clear.setOnClickListener((View.OnClickListener) this);
 button_plus.setOnClickListener((View.OnClickListener) this);
 button_minus.setOnClickListener((View.OnClickListener) this);
 button_mutiply.setOnClickListener((View.OnClickListener) this);
 button_divide.setOnClickListener((View.OnClickListener) this);
 button_equal.setOnClickListener((View.OnClickListener) this);
 button_delete.setOnClickListener((View.OnClickListener) this);
 button_clear.setOnClickListener((View.OnClickListener) this);

 }

 @Override
 public void onClick(View v) {

 //str用来保存第一个EditText中的字符串
 String str = edit_input.getText().toString();

 //str2用来保存第二个EditText中的字符串
 String str2 = editText2.getText().toString();

 switch (v.getId()) {
 case R.id.button0:
 case R.id.button1:
 case R.id.button2:
 case R.id.button3:
 case R.id.button4:
 case R.id.button5:
 case R.id.button6:
 case R.id.button7:
 case R.id.button8:
 case R.id.button9:
 case R.id.button_point:

 edit_input.setText(str + ((Button) v).getText());
 editText2.setText(str2 + ((Button) v).getText());
 break;

 // + - * / 对应的值依次为 1 2 3 4，将值传入setOperation中，就执行相应的运算
 case R.id.button_plus:

 result2.setNumber(editText2.getText().toString()); //设置操作数
 result2.getResult();
 result2.setOperation(1);
 edit_input.setText(str + " " + ((Button) v).getText() + " "); //加上空格更美观
 str2 = "";
 editText2.setText(str2); //清空textView
 break;
 case R.id.button_minus:

 result2.setNumber(editText2.getText().toString()); //设置操作数
 result2.getResult();
 result2.setOperation(2);

 edit_input.setText(str + " " + ((Button) v).getText() + " "); //加上空格更美观
 str2 = "";
 editText2.setText(str2); //清空textView
 break;
 case R.id.button_mutiply:

 result2.setNumber(editText2.getText().toString()); //设置操作数
 result2.getResult();
 result2.setOperation(3); //设置操作符

 edit_input.setText(str + " " + ((Button) v).getText() + " "); //加上空格更美观
 str2 = "";
 editText2.setText(str2); //清空textView
 break;
 case R.id.button_divide:

 result2.setNumber(editText2.getText().toString()); //设置操作数
 result2.getResult();
 result2.setOperation(4);

 edit_input.setText(str + " " + ((Button) v).getText() + " "); //加上空格更美观
 str2 = "";
 editText2.setText(str2); //清空textView
 break;

 case R.id.button_delete:

 if (str != null && !str.equals("")) {
 //substring用来截取字符串的长度

 if (str.substring(str.length() - 1, str.length()) == " ") {
 //如果最后一个字符是空格，则删除最后两个字符，且eidtText2中字符串不发生变化
 edit_input.setText(str.substring(0, str.length() - 2));
 } else {
 //如果最后一个字符是数字
 edit_input.setText(str.substring(0, str.length() - 1));
 //将EditText2中的字符取出，去掉最后一个字符之后再存入
 String c2 = editText2.getText().toString();
 String c3 = c2.substring(0, c2.length() - 1);
 editText2.setText(c3);
 }
 }
 break;
 case R.id.button_clear:
 result2.setDoubleA1(0);
 result2.setDoubleA2(0);
 result2.setA1(" ");
 result2.setA2(" ");
 edit_input.setText("");
 editText2.setText("");
 break;
 case R.id.button_equal:
 result2.setNumber(editText2.getText().toString());
 double r = result2.getResult();
 String r2 = String.valueOf(r);
 editText2.setText(r2);
 result2.setA1(" ");
 result2.setA2(" ");
 str2 = "";
 break;
 }
 }

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package com.example.calculator;

public class getResult2 {

 private String a1; //第一位操作数
 private double doubleA1; //实际参与运算

 private String a2; //第二位操作数
 private double doubleA2; //实际参与运算

 private int operation; //运算符

 double result; //结果

 //构造函数
 getResult2() {
 a1 = " ";
 a2 = " ";
 operation = 0;
 }

 void setA1(String A1) {
 a1 = A1;
 }

 void setA2(String A2) {
 a2 = A2;
 }

 void setDoubleA1(double x) {
 doubleA1 = x;
 }

 void setDoubleA2(double y) {
 doubleA2 = y;
 }
 //设置操作数,同时将字符串转换成数字，如果带小数点，转换成浮点数，否则转换成整数
 public void setNumber(String x) {
 if (a1.equals(" ")) {
 a1 = x;
 if (a1.contains(".")) {
 doubleA1 = Double.parseDouble(a1);
 } else {
 doubleA1 = Integer.parseInt(a1);
 }
 } else {
 a2 = x;
 if (a2.contains(".")) {
 doubleA2 = Double.parseDouble(a2);
 } else {
 doubleA2 = Integer.parseInt(a2);
 }
 }
 }

 public void setOperation(int i) {
 operation = i;
 }

 //进行运算，得到结果，同时将结果赋值给第一位操作数
 public double getResult() {
 if (operation == 1) {
 if (!a1.equals(" ") && a2.equals(" ")) {
 return 0;
 } else {
 result = doubleA1 + doubleA2;
 a1 = String.valueOf(result);
 doubleA1 = result;
 a2 = " ";
 }

 } else if (operation == 2) {
 if (!a1.equals("") && a2.equals("")) {
 return 0;
 } else {
 result = doubleA1 - doubleA2;
 a1 = String.valueOf(result);
 doubleA1 = result;
 a2 = " ";
 }
 } else if (operation == 3) {
 if (!a1.equals(" ") && a2.equals(" ")) {
 return 0;
 } else {
 result = doubleA1 * doubleA2;
 a1 = String.valueOf(result);
 doubleA1 = result;
 a2 = " ";
 }
 } else if (operation == 4) {
 if (!a1.equals(" ") && a2.equals(" ")) {
 return 0;
 } else {
 result = doubleA1 / doubleA2;
 a1 = String.valueOf(result);
 doubleA1 = result;
 a2 = " ";
 }
 }
 return result;
 }
}