Android Studio 2.3 陽春型計算機
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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。
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