andorid 计算器

avtivity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<GridLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="match_parent"

    android:layout_height="match_parent"

    android:rowCount="6"

    android:columnCount="4"

    >

    <!--rowCount   行数

    columnCount   列数

    layout_columnSpan    跨列

    layout_rowSpan      跨行

    fill_horizontal   水平填充

    fill_vertical    垂直填充

    layout_columnWeight   权重列

    layout_rowWeight   权重行

    background  @drawable/  设置图片

    layout_row 指定行号

    layout_column  指定列好  从0开始

    -->

    <EditText

        android:layout_columnSpan="4"

        android:layout_gravity="fill_horizontal"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:editable="false"

        android:gravity="right|center_vertical"

        android:id="@+id/et"/>

    <Button

        android:text="清除"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        android:id="@+id/clear"

        />

    <Button

        android:text="后退"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        android:id="@+id/goback"/>

    <Button

        android:text="/"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="X"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="7"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        android:id="@+id/bt_7"/>

    <Button

        android:text="8"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        android:id="@+id/bt_8"/>

    <Button

        android:text="9"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        android:id="@+id/bt_9"/>

    <Button

        android:text="-"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="4"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="5"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="6"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="+"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="1"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="2"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="3"

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"/>

    <Button

        android:text="="

        android:layout_rowSpan="2"

        android:layout_gravity="fill_vertical"

        android:layout_columnWeight="1"

        android:layout_rowWeight="2"

        android:textSize="25sp"

        android:background="#24f"

        />

    <Button

        android:text="0"

        android:layout_columnSpan="2"

        android:layout_gravity="fill_horizontal"

        android:layout_columnWeight="2"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        />

    <Button

        android:text="."

        android:layout_columnWeight="1"

        android:layout_rowWeight="1"

        android:textSize="25sp"

        />

</GridLayout>

CalculatorActivity

package com.hanqi.application3;

import android.app.Activity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

import android.widget.EditText;

/**

 * Created by Administrator on 2016/3/28.

 */

public class CalculatorActivity extends Activity implements View.OnClickListener {

    EditText et;

    Button  bt_clear;

    Button  bt_goback;

    Button  bt_7;

    Button  bt_8;

    Button  bt_9;

    //构建字符串StringBuffer

    //存储显示的内容

    private StringBuffer str_show= new StringBuffer();

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.avtivity_main);

        et=(EditText)findViewById(R.id.et);

        bt_clear=(Button)findViewById(R.id.clear);

        bt_7=(Button)findViewById(R.id.bt_7);

        bt_8=(Button)findViewById(R.id.bt_8);

        bt_9=(Button)findViewById(R.id.bt_9);

        bt_clear.setOnClickListener(this);

        bt_goback.setOnClickListener(this);

        bt_7.setOnClickListener(this);

        bt_8.setOnClickListener(this);

        bt_9.setOnClickListener(this);

    }

    public void onClick(View v)

    {

        Button bt = (Button)v;

        int id =bt.getId();

        switch (id)

        {

            case R.id.clear:

                str_show= new StringBuffer();

                et.setText(str_show);

                break;

            case R.id.goback:

                str_show.codePointAt(str_show.length()-1);

                et.setText(str_show);

                break;

            case R.id.bt_7:

            case R.id.bt_8:

            case R.id.bt_9:

                str_show.append(bt.getText());

                et.setText(str_show);

                break;

        }

    }

}