innstory

Android Studio 2.3 陽春型計算機

原本這次的學習課題是，與使用者互動之「按一下」事件處理。

我按照工具書上寫的，完成了按一下Button 會達到累加數字的效果。

但是沒耐心的我，總覺得這樣的學習方式好枯燥無味。

因此，為了讓學習變有趣，既然是「按一下」事件處理，那這次索性訂了個專題，寫個計算機吧。

MainActivity.java部分

package com.innstory.computer;





import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.view.View.OnClickListener;

import android.view.View.OnLongClickListener;

import android.widget.Button;

import android.widget.EditText;

import android.widget.TextView;









public class MainActivity extends AppCompatActivity

implements View.OnClickListener, View.OnLongClickListener{



//定義變數

TextView ans_list_s,ans_list;//輸出點擊按鈕及輸出結果

Button bt1,bt2,bt3,bt4,bt5,bt6,bt7,bt8,bt9,bt0,bt_add,bt_less,bt_Multiply

,bt_except,bt_ac,bt_answer;//按鈕

int previous = 0;//儲存上1筆資料

int counter = 0; //目前的值

int counter_ = 0;//原運算值

String Operation;//運算符號





@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

ans_list = (TextView) findViewById(R.id.ans_list);

ans_list_s = (TextView) findViewById(R.id.ans_list_s);

bt1 = (Button) findViewById(R.id.button1);

bt2 = (Button) findViewById(R.id.button2);

bt3 = (Button) findViewById(R.id.button3);

bt4 = (Button) findViewById(R.id.button4);

bt5 = (Button) findViewById(R.id.button5);

bt6 = (Button) findViewById(R.id.button6);

bt7 = (Button) findViewById(R.id.button7);

bt8 = (Button) findViewById(R.id.button8);

bt9 = (Button) findViewById(R.id.button9);

bt0 = (Button) findViewById(R.id.button0);

bt_add = (Button) findViewById(R.id.button_add);

bt_less = (Button) findViewById(R.id.button_less);

bt_Multiply = (Button) findViewById(R.id.button_Multiply);

bt_except = (Button) findViewById(R.id.button_except);

bt_ac = (Button) findViewById(R.id.button_ac);

bt_answer = (Button) findViewById(R.id.button_answer);



bt1.setOnClickListener(this);

bt2.setOnClickListener(this);

bt3.setOnClickListener(this);

bt4.setOnClickListener(this);

bt5.setOnClickListener(this);

bt6.setOnClickListener(this);

bt7.setOnClickListener(this);

bt8.setOnClickListener(this);

bt9.setOnClickListener(this);

bt0.setOnClickListener(this);

bt_add.setOnClickListener(this);

bt_less.setOnClickListener(this);

bt_Multiply.setOnClickListener(this);

bt_except.setOnClickListener(this);

bt_ac.setOnClickListener(this);

bt_answer.setOnClickListener(this);



}





@Override

public void onClick(View v) {

if (v.getId() == R.id.button1){

counter = counter * 10 + 1; // x 10 原因為了進位

} else if (v.getId() == R.id.button2){

counter = counter * 10 + 2;

} else if (v.getId() == R.id.button3){

counter = counter * 10 + 3;

} else if (v.getId() == R.id.button4){

counter = counter * 10 + 4;

} else if (v.getId() == R.id.button5){

counter = counter * 10 + 5;

} else if (v.getId() == R.id.button6){

counter = counter * 10 + 6;

} else if (v.getId() == R.id.button7){

counter = counter * 10 + 7;

} else if (v.getId() == R.id.button8){

counter = counter * 10 + 8;

} else if (v.getId() == R.id.button9){

counter = counter * 10 + 9;

} else if (v.getId() == R.id.button0){

counter = counter * 10 + 0;

} else if (v.getId() == R.id.button_ac){

counter = 0;

ans_list.setText(String.valueOf(counter));

ans_list_s.setText(String.valueOf(counter));

}



ans_list.setText(String.valueOf(counter));



//符號

if (v.getId() == R.id.button_add){

previous = counter;

counter = 0;

Operation = bt_add.getText().toString();

ans_list.setText(String.valueOf(Operation));

}



else if (v.getId() == R.id.button_less){

previous = counter;

counter = 0;

Operation = bt_less.getText().toString();

ans_list.setText(String.valueOf(Operation));

}



else if (v.getId() == R.id.button_Multiply){

previous = counter;

counter = 0;

Operation = bt_Multiply.getText().toString();

ans_list.setText(String.valueOf(Operation));

}



else if (v.getId() == R.id.button_except){

previous = counter;

counter = 0;

Operation = bt_except.getText().toString();

ans_list.setText(String.valueOf(Operation));

}





//運算

if (v.getId() == R.id.button_answer){

if(Operation.equals("+")){

counter = previous + counter;

counter_ = counter - previous;

ans_list.setText(String.valueOf(counter));

ans_list_s.setText("運算子 = " + previous + " + " + counter_);

previous = 0;

}



else if(Operation.equals("－")){

counter = previous - counter;

counter_ = previous - counter;

ans_list.setText(String.valueOf(counter));

ans_list_s.setText("運算子 = " + previous + " - " + counter_);

previous = 0;

}



else if(Operation.equals("×")){

counter = previous * counter;

counter_ = counter / previous;

ans_list.setText(String.valueOf(counter));

ans_list_s.setText("運算子 = " + previous + " × " + counter_);

previous = 0;

}



else if(Operation.equals("÷")){

if (counter == 0) {

ans_list.setText("被除數除數不能為0");

previous = 0;

}else {

counter = previous / counter;

counter_ = previous / counter;

ans_list.setText(String.valueOf(counter));

ans_list_s.setText("運算子 = " + previous + " ÷ " + counter_);

previous = 0;

}

}

}





}



@Override

public boolean onLongClick(View v) {

return false;

}

}

當然，這只是一個極度陽春的計算機功能。

有一些bug可能也還需要研究怎麼處理，UI部分也要研究如何讓他變漂亮。

嗯，其實還可以多加個「未稅」「含稅」的Button。

但撇開這些缺點不談，他的確是個計算機了。