终于做了第一个可以用的~~~计算器 为自己鼓掌

很简单 老规矩先把代码贴上来

package com.example.admin.test_0306_2;

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

public class MainActivity extends Activity implements View.OnClickListener{
    private Button button_0;
    private Button button_1;
    private Button button_2;
    private Button button_3;
    private Button button_4;
    private Button button_5;
    private Button button_6;
    private Button button_7;
    private Button button_8;
    private Button button_9;
    private Button button_c;
    private Button button_del;
    private Button button_jia;
    private Button button_jian;
    private Button button_cheng;
    private Button button_chu;
    private Button button_equal;
    private Button button_point;
    private EditText editText;
    Boolean flag_clear;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button_0= (Button) findViewById(R.id.button_0);
        button_1= (Button) findViewById(R.id.button_1);
        button_2= (Button) findViewById(R.id.button_2);
        button_3= (Button) findViewById(R.id.button_3);
        button_4= (Button) findViewById(R.id.button_4);
        button_5= (Button) findViewById(R.id.button_5);
        button_6= (Button) findViewById(R.id.button_6);
        button_7= (Button) findViewById(R.id.button_7);
        button_8= (Button) findViewById(R.id.button_8);
        button_9= (Button) findViewById(R.id.button_9);
        button_c= (Button) findViewById(R.id.button_c);
        button_del= (Button) findViewById(R.id.button_del);
        button_cheng= (Button) findViewById(R.id.button_cheng);
        button_chu= (Button) findViewById(R.id.button_chu);
        button_jia= (Button) findViewById(R.id.button_jia);
        button_jian= (Button) findViewById(R.id.button_jian);
        button_equal= (Button) findViewById(R.id.button_equal);
        button_point= (Button) findViewById(R.id.button_point);
        editText= (EditText) findViewById(R.id.input);
        flag_clear=false;

        button_0.setOnClickListener(this);
        button_1.setOnClickListener(this);
        button_2.setOnClickListener(this);
        button_3.setOnClickListener(this);
        button_4.setOnClickListener(this);
        button_5.setOnClickListener(this);
        button_6.setOnClickListener(this);
        button_7.setOnClickListener(this);
        button_8.setOnClickListener(this);
        button_9.setOnClickListener(this);
        button_c.setOnClickListener(this);
        button_del.setOnClickListener(this);
        button_cheng.setOnClickListener(this);
        button_chu.setOnClickListener(this);
        button_jia.setOnClickListener(this);
        button_jian.setOnClickListener(this);
        button_equal.setOnClickListener(this);
        button_point.setOnClickListener(this);

    }

    @Override
    public void onClick(View v) {
        String str=editText.getText().toString();
        switch (v.getId()){
            case R.id.button_0:
            case R.id.button_1:
            case R.id.button_2:
            case R.id.button_3:
            case R.id.button_4:
            case R.id.button_5:
            case R.id.button_6:
            case R.id.button_7:
            case R.id.button_8:
            case R.id.button_9:
            case R.id.button_point:
                if(flag_clear){
                    flag_clear=false;
                    str="";
                    editText.setText("");
                }
                editText.setText(str+((Button)v).getText());
            break;
            case R.id.button_jia:
            case R.id.button_jian:
            case R.id.button_cheng:
            case R.id.button_chu:
                if(flag_clear){
                    flag_clear=false;
                    str="";
                    editText.setText("");
                }
                editText.setText(str+" "+((Button)v).getText()+" ");
                break;
            case R.id.button_c:
                flag_clear=false;
                str="";
                editText.setText("");
                break;
            case R.id.button_del:
                if(flag_clear){
                    flag_clear=false;
                    str="";
                    editText.setText("");
                }else if(str!=null&&!str.equals("")){
                    editText.setText(str.substring(0,str.length()-1));
                    break;
                }
            case R.id.button_equal:
                getresult();
                break;
        }

    }
    private void getresult(){
        String exp=editText.getText().toString();
        if(exp==null||exp.equals("")){
            return;
        }
        if(!exp.contains(" ")){
            return;
        }
        if(flag_clear){
            flag_clear=false;
            return;
        }
        flag_clear=true;
        double result=0;
        String s1=exp.substring(0,exp.indexOf(" "));
        String op=exp.substring(exp.indexOf(" ") + 1, exp.indexOf(" ") + 2);
        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("÷")){
                if(d2==0){
                    result=0;
                }
            }
            if(!s2.contains(".")){
                int r=(int)result;
                editText.setText(r+"");
            }else{
                editText.setText(result+"");
            }
        }else{
            editText.setText("");
        }

    }
}

其中有几个知识点 记一下

.contains(" ")

是指对象中包含了空格

String s1=exp.substring(0,exp.indexOf(" "));
String op=exp.substring(exp.indexOf(" ") + 1, exp.indexOf(" ") + 2);
String s2=exp.substring(exp.indexOf(" ") + 3);

这个.subsyring(a,b)是指去字符串的第几个到第几个 indexOf（）是获取到第一个“ ”

Double.parseDouble(s1)

强制转换啦

确实感觉自己java底子很差  所以都记下来  不能嫌烦燥

当然布局代码昨天就已经贴出来了  今天按照自己iphone的布局稍微修改了一下  确实好看多了 呼呼呼

毕竟是做的第一个可以用的  成就感爆棚呀