1.MainActivity
package com.example.flyyu.first2;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.EditText;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity implements View.OnClickListener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public void onClick(View v) {
EditText editTextren = (EditText)findViewById(R.id.editTextren);
EditText editTextmei = (EditText)findViewById(R.id.editTextmei);
EditText editTexthui = (EditText)findViewById(R.id.editTexthui);
double R1 = 0;
double M;
double Huan;
String a;
String s;
String b;
if (v.getId()==R.id.button){
a=editTextren.getText().toString();
if("".equals(a)){
R1 = 0;
}
else{
R1 =Float.valueOf(a);
}
b=editTexthui.getText().toString();
if("".equals(b)){
Huan = 0;
}
else{
Huan =Float.valueOf(b);
}
if (Huan==0){
Toast.makeText(MainActivity.this,"输入有误",Toast.LENGTH_SHORT).show();
}
else {
M=R1/Huan;
editTextmei.setText(M+"");
}
}
else{
a=editTextmei.getText().toString();
if("".equals(a)){
M = 0;
}
else{
M =Float.valueOf(a);
}
b=editTexthui.getText().toString();
if("".equals(b)){
Huan = 0;
}
else{
Huan =Float.valueOf(b);
}
if (Huan==0){
Toast.makeText(MainActivity.this,"输入有误",Toast.LENGTH_SHORT).show();
}else {
R1=M*Huan;
editTextren.setText(R1+"");
}
}
}
}
2.activity_main
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.flyyu.first2.MainActivity">
<LinearLayout
android:layout_width="368dp"
android:layout_height="495dp"
android:orientation="vertical"
tools:layout_editor_absoluteY="8dp"
tools:layout_editor_absoluteX="8dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="@+id/textView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:layout_weight="1"
android:text="人民币金额:"
app:layout_constraintBottom_toTopOf="@+id/edittxt_ren"
app:layout_constraintHorizontal_bias="0.176"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/edittxt_huilv"
app:layout_constraintVertical_bias="0.812" />
<EditText
android:id="@+id/editTextren"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:layout_weight="1"
android:ems="10"
android:inputType="numberDecimal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.326"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.181" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="@+id/textView2"
android:layout_width="match_parent"
android:layout_height="27dp"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:layout_weight="1"
android:text="美元兑人民币汇率:"
app:layout_constraintBottom_toTopOf="@+id/edittxt_huilv"
app:layout_constraintHorizontal_bias="0.226"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/edittxt_mei"
app:layout_constraintVertical_bias="1.0" />
<EditText
android:id="@+id/editTexthui"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="7dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:layout_weight="1"
android:ems="10"
android:inputType="numberDecimal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.326"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.607" />
</LinearLayout>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<TextView
android:id="@+id/textView3"
android:layout_width="match_parent"
android:layout_height="27dp"
android:layout_marginBottom="0dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:layout_weight="1"
android:text="美元金额:"
app:layout_constraintBottom_toTopOf="@+id/edittxt_mei"
app:layout_constraintHorizontal_bias="0.182"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.744" />
<EditText
android:id="@+id/editTextmei"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="8dp"
android:layout_weight="1"
android:ems="10"
android:inputType="numberDecimal"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.326"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.389" />
</LinearLayout>
<Button
android:id="@+id/button"
android:layout_width="match_parent"
android:layout_height="39dp"
android:layout_marginBottom="8dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="28dp"
android:onClick="onClick"
android:text="美元转人民币"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.287"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/btn_ren"
app:layout_constraintVertical_bias="0.088" />
<Button
android:id="@+id/button2"
android:layout_width="match_parent"
android:layout_height="40dp"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:onClick="onClick"
android:text="人民币转美元"
app:layout_constraintHorizontal_bias="0.29"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/edittxt_ren"
tools:layout_editor_absoluteY="350dp" />
</LinearLayout>
</android.support.constraint.ConstraintLayout>