android:第一个android项目 简单计算器

以前自己写过java版的简单计算器 代码其实都一样就是改改布局

不过我现在不会获取屏幕大小。。然后按照比例设置按钮的长宽。所以先这样凑合把

都在左上角。。

像这样

/*知道怎么获取屏幕的尺寸了
int height=this.getResources().getDisplayMetrics().heightPixels;//获取屏幕的高
int width=this.getResources().getDisplayMetrics().widthPixels;//获取屏幕的宽
然后在MainActivity.java中的onCreate方法里面for循环里面添加
button[i].setWidth(width/4);
button[i].setHeight(height/6);
就能让计算器按钮铺满屏幕了~我就不修改了 */

我用的相对布局 感觉这样比较方便

layout文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
	android:id="@+id/relativeLayout"
	>
	<EditText 
	    android:id="@+id/print"
	    android:layout_height="wrap_content"
	    android:layout_width="fill_parent"
	    />
	<Button 
	    android:id="@+id/left"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="("
	    android:gravity="center"
	    android:layout_below="@+id/print"
	    />
	<Button 
	    android:id="@+id/right"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text=")"
	    android:gravity="center"
	    android:layout_below="@+id/print"
	    android:layout_toRightOf="@+id/left"
	    />
	<Button 
	    android:id="@+id/delect"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="清除"
	    android:gravity="center"
	    android:layout_below="@+id/print"
	    android:layout_toRightOf="@+id/right"
	    />
	<Button 
	    android:id="@+id/back"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="退格"
	    android:gravity="center"
	    android:layout_below="@+id/print"
	    android:layout_toRightOf="@+id/delect"
	    />
	<Button 
	    android:id="@+id/seven"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="7"
	    android:gravity="center"
	    android:layout_below="@+id/left"
	    />
	<Button 
	    android:id="@+id/eight"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="8"
	    android:gravity="center"
	    android:layout_below="@+id/right"
	    android:layout_toRightOf="@+id/seven"
	    />
	<Button 
	    android:id="@+id/nine"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="9"
	    android:gravity="center"
	    android:layout_below="@+id/delect"
	    android:layout_toRightOf="@+id/eight"
	    />
	<Button 
	    android:id="@+id/div"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="/"
	    android:gravity="center"
	    android:layout_below="@+id/back"
	    android:layout_toRightOf="@+id/delect"
	    />
	<Button 
	    android:id="@+id/four"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="4"
	    android:gravity="center"
	    android:layout_below="@+id/seven"
	    />
	<Button 
	    android:id="@+id/five"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="5"
	    android:gravity="center"
	    android:layout_below="@+id/eight"
	    android:layout_toRightOf="@+id/four"
	    />
	<Button 
	    android:id="@+id/six"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="6"
	    android:gravity="center"
	    android:layout_below="@+id/nine"
	    android:layout_toRightOf="@+id/five"
	    />
	<Button 
	    android:id="@+id/mul"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="*"
	    android:gravity="center"
	    android:layout_below="@+id/div"
	    android:layout_toRightOf="@+id/nine"
	    />
	<Button 
	    android:id="@+id/one"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="1"
	    android:gravity="center"
	    android:layout_below="@+id/four"
	    />
	<Button 
	    android:id="@+id/two"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="2"
	    android:gravity="center"
	    android:layout_below="@+id/five"
	    android:layout_toRightOf="@+id/one"
	    />
	<Button 
	    android:id="@+id/three"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="3"
	    android:gravity="center"
	    android:layout_below="@+id/six"
	    android:layout_toRightOf="@+id/two"
	    />
	<Button 
	    android:id="@+id/sub"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="-"
	    android:gravity="center"
	    android:layout_below="@+id/mul"
	    android:layout_toRightOf="@+id/three"
	    />
	<Button 
	    android:id="@+id/point"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="."
	    android:gravity="center"
	    android:layout_below="@+id/one"
	    />
	<Button 
	    android:id="@+id/zero"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="0"
	    android:gravity="center"
	    android:layout_below="@+id/two"
	    android:layout_toRightOf="@+id/point"
	    />
	<Button 
	    android:id="@+id/equal"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="="
	    android:gravity="center"
	    android:layout_toRightOf="@+id/zero"
	    android:layout_below="@+id/three"
	    />
	<Button 
	    android:id="@+id/add"
	    android:layout_width="wrap_content"
	    android:layout_height="wrap_content"
	    android:text="+"
	    android:gravity="center"
	    android:layout_toRightOf="@+id/equal"
	    android:layout_below="@+id/sub"
	    />
	
</RelativeLayout>

MainActivity.java主要是添加事件监听器

package com.example.simplecalculator;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener {
	//private Button one,two,three,four,five,six,seven,eight,nine,ten,point,add,div,mul,sub;
	private Button button[];
	public EditText text;
	private int id[]={R.id.one,R.id.two,R.id.three,R.id.four,R.id.five,R.id.six,R.id.seven,
			R.id.eight,R.id.nine,R.id.zero,R.id.point,R.id.add,R.id.sub,R.id.mul,R.id.div,
			R.id.left,R.id.right,R.id.delect,R.id.back,R.id.equal};
	private EditText editText;
	private Cal cal_str;
	boolean equal=false;
	public MainActivity() {
		// TODO Auto-generated constructor stub
	}
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);
		button =new Button[id.length];
		for(int i=0;i<id.length;i++){
			button[i]=(Button) findViewById(id[i]);
			button[i].setOnClickListener(MainActivity.this);
		}
	}
	@Override
	public void onClick(View view) {
		// TODO Auto-generated method stub
		Button btn =(Button) findViewById(view.getId());
		EditText print=(EditText) findViewById(R.id.print);
		if(btn.getId()==R.id.delect){
			print.setText(null);
		}
		else if(btn.getId()==R.id.back){
			char str[]=print.getText().toString().toCharArray();
			if(str.length>=1)
			print.setText(new String(str,0,str.length-1));
		}
		else if(btn.getId()==R.id.equal){
			String str=print.getText().toString();
			if(str.equals("1+99")||str.equals("99+1")){
				Toast.makeText(MainActivity.this, "我向你走了99步，最后一步我们一起走。", Toast.LENGTH_LONG).show();
				Toast.makeText(MainActivity.this, "I LOVE YOU", Toast.LENGTH_LONG).show();
			}
			equal=true;
			cal_str=new Cal(print,str+"=");
		}
		else{
			if(equal){
				equal=false;
				print.setText(null);
			}
			print.setText(print.getText()+btn.getText().toString());
		}
	}

}

Cal.java 对获取的字符串进行运算  学过数据结构的都知道运算符优先级把。

package com.example.simplecalculator;

import java.util.Stack;

import android.widget.EditText;
import android.widget.Toast;

public class Cal {
	
	public Cal(EditText print,String str) {
		// TODO Auto-generated constructor stub
		char temp[]=new char[100];
		Stack<Character> optr=new Stack<Character>();
		Stack<Double> opnd=new Stack<Double>();
		int k=0,count=0;
		boolean flag=false;
		optr.clear();
		opnd.clear();
		optr.add('=');
		try{
			for(int i=0;i<str.length();){
				if(count++>1000)
					flag=true;
				char ch=str.charAt(i);
				if(Character.isDigit(ch)||ch=='.'){
					temp[k++]=ch;
					i++;
					continue;
				}
				if(k!=0){
					opnd.add(Double.parseDouble(new String(temp,0,k)));
					k=0;
				}
				switch(compare(optr.peek(),ch)){
				case -1:flag=true;break;
				case 60:optr.add(ch);i++;break;
				case 61:optr.pop();i++;break;
				case 62:opnd.add(result(opnd.pop(),opnd.pop(),optr.pop()));break;
				}
				if(flag){
					break;
				}
			}
			if(flag)
				print.setText("请输入合法字符");
			else
				print.setText(opnd.pop().toString());
		}
		catch(Exception e){
			print.setText("请输入合法字符");
		}
		
	}

	private Double result(Double num1, Double num2, char ch) {
		// TODO Auto-generated method stub
		if(ch=='+')  
	        return num2+num1;  
	    if(ch=='-')  
	        return num2-num1;  
	    if(ch=='*')  
	        return num2*num1;  
	    if(ch=='/')  
	        return num2/num1;
		return num2;  
	}

	private int compare(char ch1, char ch2) {
		// TODO Auto-generated method stub
		    String oper[]={">><<<>>",">><<<>>",">>>><>>",  
		            ">>>><>>","<<<<<= ",">>>> >>","<<<<< ="};  
		    int x,y;  
		    x=to_num(ch1);  
		    y=to_num(ch2);  
		    if(x==-1||y==-1)
		    	return -1;
		    return (int)(oper[x].charAt(y));        
	}

	private int to_num(char ch) {
		// TODO Auto-generated method stub
		 if(ch=='+')  
			 return 0;  
		 else if(ch=='-')  
			 return 1;  
		 else if(ch=='*')  
		     return 2;  
		 else if(ch=='/')  
		     return 3;  
		 else if(ch=='(')  
			 return 4;  
		 else if(ch==')')  
		     return 5;  
		 else if(ch=='=')  
			 return 6;  
		 else
			 return -1;
	}

}

就这么多 当你输入99+1 或者1+99 看看结果 哈哈~

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