LTY博客

package lty.example.calculator;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

public class MainActivity extends ActionBarActivity implements OnClickListener {
	// 初始化显示屏
	EditText editText1;
	// 初始化按钮
	Button btn_clear;
	Button btn_del;
	Button btn_7;
	Button btn_8;
	Button btn_9;
	Button btn_divide;
	Button btn_4;
	Button btn_5;
	Button btn_6;
	Button btn_multiply;
	Button btn_1;
	Button btn_2;
	Button btn_3;
	Button btn_reduce;
	Button btn_genhao;
	Button btn_0;
	Button btn_point;
	Button btn_add;
	Button btn_equal;

@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// 去掉状态栏
		this.requestWindowFeature(Window.FEATURE_NO_TITLE);
		// 隐藏状态栏
		this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
				WindowManager.LayoutParams.FLAG_FULLSCREEN);
		setContentView(R.layout.activity_main);

// 实例化显示屏
		editText1 = (EditText) findViewById(R.id.editText1);
		// 实例化按钮
		btn_clear = (Button) findViewById(R.id.btn_clear);
		btn_del = (Button) findViewById(R.id.btn_del);
		btn_7 = (Button) findViewById(R.id.btn_7);
		btn_8 = (Button) findViewById(R.id.btn_8);
		btn_9 = (Button) findViewById(R.id.btn_9);
		btn_divide = (Button) findViewById(R.id.btn_divide);
		btn_4 = (Button) findViewById(R.id.btn_4);
		btn_5 = (Button) findViewById(R.id.btn_5);
		btn_6 = (Button) findViewById(R.id.btn_6);
		btn_multiply = (Button) findViewById(R.id.btn_multiply);
		btn_1 = (Button) findViewById(R.id.btn_1);
		btn_2 = (Button) findViewById(R.id.btn_2);
		btn_3 = (Button) findViewById(R.id.btn_3);
		btn_reduce = (Button) findViewById(R.id.btn_reduce);
		btn_genhao = (Button) findViewById(R.id.btn_genhao);
		btn_0 = (Button) findViewById(R.id.btn_0);
		btn_point = (Button) findViewById(R.id.btn_point);
		btn_add = (Button) findViewById(R.id.btn_add);
		btn_equal = (Button) findViewById(R.id.btn_equal);
		
		//添加点击
		btn_clear.setOnClickListener(this);
		btn_del.setOnClickListener(this);
		btn_7.setOnClickListener(this);
		btn_8.setOnClickListener(this);
		btn_9.setOnClickListener(this);
		btn_divide.setOnClickListener(this);
		btn_4.setOnClickListener(this);
		btn_5.setOnClickListener(this);
		btn_6.setOnClickListener(this);
		btn_multiply.setOnClickListener(this);
		btn_1.setOnClickListener(this);
		btn_2.setOnClickListener(this);
		btn_3.setOnClickListener(this);
		btn_reduce.setOnClickListener(this);
		btn_genhao.setOnClickListener(this);
		btn_0.setOnClickListener(this);
		btn_point.setOnClickListener(this);
		btn_add.setOnClickListener(this);
		btn_equal.setOnClickListener(this);

}
	
	//设置清屏标志
	boolean clearFlag = false;
	@Override
	public void onClick(View v) {
		// 获取显示屏的当前文内容
		String str = editText1.getText().toString();
		switch (v.getId()) {
		// 清除按钮
		case R.id.btn_clear:
			editText1.setText("");
			break;
		// 删除按钮
		case R.id.btn_del:
			if (str.length() > 0) {
				editText1.setText(str.substring(0, str.length() - 1));
			}
			break;
		// 数字键按钮
		case R.id.btn_0:
		case R.id.btn_1:
		case R.id.btn_2:
		case R.id.btn_3:
		case R.id.btn_4:
		case R.id.btn_5:
		case R.id.btn_6:
		case R.id.btn_7:
		case R.id.btn_8:
		case R.id.btn_9:
			if(clearFlag){
				str = "";
				clearFlag = false;
			}
			editText1.setText(str + ((Button) v).getText());
			break;

case R.id.btn_point:
			if(str.length() == 0 || str.substring(str.length()-1).equals("+") || str.substring(str.length()-1).equals("-") || str.substring(str.length()-1).equals("×") || str.substring(str.length()-1).equals("÷")){
				editText1.setText(str + "0.");
			}else if(str.contains(".")){
				if(str.contains("+")){//包含操作符+
					if(str.substring(str.lastIndexOf("+")).contains(".")){
						editText1.setText(str);
					}else{
						editText1.setText(str + ((Button) v).getText());
					}
				}else if(str.contains("-")){//包含操作符-
					if(str.substring(str.lastIndexOf("-")).contains(".")){
						editText1.setText(str);
					}else{
						editText1.setText(str + ((Button) v).getText());
					}
				}else if(str.contains("×")){//包含操作符×
					if(str.substring(str.lastIndexOf("×")).contains(".")){
						editText1.setText(str);
					}else{
						editText1.setText(str + ((Button) v).getText());
					}
				}else if(str.contains("÷")){//包含操作符÷
					if(str.substring(str.lastIndexOf("÷")).contains(".")){
						editText1.setText(str);
					}else{
						editText1.setText(str + ((Button) v).getText());
					}
				}
			}else{
				editText1.setText(str + ((Button) v).getText());
			}
			break;
		// 操作按钮+-*/
		case R.id.btn_add:
		case R.id.btn_reduce:
		case R.id.btn_multiply:
		case R.id.btn_divide:
			if(clearFlag){
				clearFlag = false;
			}
			
			if(str.length() == 0 && v.getId() == R.id.btn_reduce){
				editText1.setText("-");
			}else if(str.length() == 0 && (v.getId() == R.id.btn_add || v.getId() == R.id.btn_multiply || v.getId() == R.id.btn_divide)){
				editText1.setText("");
			}else if(str.length() == 1 && str.substring(0,1).equals("-")){
				editText1.setText(str);
			}else if(str.length() == 1 && !str.substring(0,1).equals("-")){
				editText1.setText(str + ((Button) v).getText());
			}else if(str.length() > 1 && (str.contains("+") || str.substring(1).contains("-") || str.contains("×") || str.contains("÷"))){
				editText1.setText(str);
			}else{
				editText1.setText(str + ((Button) v).getText());
			}
			break;
		// 等号按钮
		case R.id.btn_equal:
			// 调用Result()计算结果
			clearFlag = true;
			Result(str);
			break;
		// 根号或感叹号按钮
		case R.id.btn_genhao:
			Toast.makeText(this, "作者：林廷勇\n时间：2016\\04\\08", Toast.LENGTH_SHORT).show();
		}// switch() end
	}// onClick end

// Result()方法 ，参数 :当前是显示屏的内容
	public void Result(String str) {
		String a;// 第一个操作数
		String b;// 第二个操作数
		String result = null;// 结果
		if(str.length() > 0){
			if(!str.substring(0,1).equals("-")){//第一个操作数为正数
				if (str.contains("+")) {
					a = str.substring(0, str.indexOf("+"));
					b = str.substring(str.indexOf("+") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(a) + Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else if (str.contains("-")) {
					a = str.substring(0, str.indexOf("-"));
					b = str.substring(str.indexOf("-") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(a) - Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else if (str.contains("×")) {
					a = str.substring(0, str.indexOf("×"));
					b = str.substring(str.indexOf("×") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(a) * Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else if (str.contains("÷")) {
					a = str.substring(0, str.indexOf("÷"));
					b = str.substring(str.indexOf("÷") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(a) / Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else {
					result = str;
				}
			}else{//第一个操作数为负数
				if (str.contains("+")) {
					a = str.substring(1, str.indexOf("+"));
					b = str.substring(str.indexOf("+") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(b) - Double.parseDouble(a));
					}else{
						clearFlag = false;
						result = str;
					}
				} else if (str.substring(1, str.length()).contains("-")) {
					a = str.substring(0,str.lastIndexOf("-"));
					b = str.substring(str.lastIndexOf("-") + 1, str.length());
					if(b.length() != 0){
						result =String.valueOf(Double.parseDouble(a) - Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else if (str.contains("×")) {
					a = str.substring(0, str.indexOf("×"));
					b = str.substring(str.indexOf("×") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(a) * Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else if (str.contains("÷")) {
					a = str.substring(0, str.indexOf("÷"));
					b = str.substring(str.indexOf("÷") + 1, str.length());
					if(b.length() != 0){
						result = String.valueOf(Double.parseDouble(a) / Double.parseDouble(b));
					}else{
						clearFlag = false;
						result = str;
					}
				} else {
					result = str;
				}
			}
		}
		editText1.setText(result);
	}

}

编写第一个Android程序-计算器