通常輸入數值都會使用EditText等等的文字框當作對象, 如何才能很快速的從這些view取得數值呢??
使用 getText().toString() 加上各個數值類別(Integer, Double, Float, Long, Byte, Short)的ParseXXX() 最快 如下
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
public class GetValueFromTextView extends Activity
{
private static final int PERCENT = 100;
private static final int MONTH_COUNT = 12;
private EditText mInput_lend;
private EditText mInputRate;
private EditText mInputNumber;
private Button mSubmit;
private TextView mAmount;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
initComponents();
}
private void initComponents()
{
mInput_lend = (EditText) findViewById(R.id.input_lend);
mInputNumber = (EditText) findViewById(R.id.input_number);
mInputRate = (EditText) findViewById(R.id.input_rate);
mSubmit = (Button) findViewById(R.id.submit);
mSubmit.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v)
{
mAmount.setText("" + countAmount());
}
});
mAmount = (TextView) findViewById(R.id.amount);
}
private double countAmount()
{
int lend = Integer.parseInt(mInput_lend.getText().toString());
double rateOfMonth = Double.parseDouble(mInputRate.getText().toString()) / MONTH_COUNT
/ PERCENT;
int number = Integer.parseInt(mInputNumber.getText().toString());
return lend * (Math.pow(rateOfMonth + 1, number));
}
}
重點在 countAmount 方法中, 以下列方式取得string並轉換成數字
int lend = Integer.parseInt(mInput_lend.getText().toString()); double rateOfMonth = Double.parseDouble(mInputRate.getText().toString()) / MONTH_COUNT / PERCENT; int number = Integer.parseInt(mInputNumber.getText().toString());
但要小心轉型溢位的問題
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/main_tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/title"/>
<TextView
android:id="@+id/main_tv_lendHint"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/lend"/>
<EditText
android:id="@+id/input_lend"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:inputType="number"/>
<TextView
android:id="@+id/main_tv_rateHint"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/rate"/>
<EditText
android:id="@+id/input_rate"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:inputType="numberDecimal"/>
<TextView
android:id="@+id/main_tv_number"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/rate"/>
<EditText
android:id="@+id/input_number"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:inputType="number"/>
<Button
android:id="@+id/submit"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/btn"/>
<TextView
android:id="@+id/amount"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
以及 strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Count Round-amount savings</string>
<string name="title">Round-amount savings:</string>
<string name="lend">capital(NT$):</string>
<string name="rate">rate of year(%):</string>
<string name="number">number of periods:</string>
<string name="btn">count</string>
</resources>