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