用android制作一个简单的计算器
我正在用android做一个计算器,但由于某些原因,它不允许我阅读编辑文本。这是我用来声明编辑文本的代码:用android制作一个简单的计算器,android,android-edittext,double,calculator,Android,Android Edittext,Double,Calculator,我正在用android做一个计算器,但由于某些原因,它不允许我阅读编辑文本。这是我用来声明编辑文本的代码: final EditText AnswerBox = (EditText) findViewById(R.id.AnswerBox); 这是其中一个按钮的代码: one.setOnClickListener(new View.OnClickListener() { public void onClick (View v) { An
final EditText AnswerBox = (EditText) findViewById(R.id.AnswerBox);
这是其中一个按钮的代码:
one.setOnClickListener(new View.OnClickListener() {
public void onClick (View v) {
AnswerBox.append("1");
}
});
}
这是读取数字的方法:
public Double number_reader()
{
Double num1;
String s;
s=AnswerBox.getText().toString();
num1=Double.valueOf(s);
return num1;
}
问题在于数字阅读器方法中的应答器,它表示无法解决 您将其声明为final,并将其创建为空。您可能会在
onCreate
方法中声明AnswerBox
:
final EditText AnswerBox = (EditText) findViewById(R.id.AnswerBox);
现在,AnswerBox
是一个局部变量,它不存在于onCreate
方法之外,因此在方法number\u reader
中找不到它
要解决此问题,请在类中创建一个私有字段:
private final EditText AnserBox;
然后在onCreate
方法中执行以下操作:
AnswerBox = (EditText) findViewById(R.id.AnswerBox);
我认为您需要使用Double.parseDouble来代替。如果需要,可以参考我给出的答案,删除final关键字并在类字段中添加EditText(在所有方法之外声明,但在活动中声明)。在那之后,就可以读写编辑文本了。
还有一点需要注意的是,变量名的首字母大写并不是一个好的做法,这是针对类或接口的。请尝试使用小写。您可以尝试此代码
package com.example.showoff;
import java.util.ArrayList;
import android.os.Bundle;
import android.app.Activity;
import android.text.method.DigitsKeyListener;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
TextView edittest1;
Button one, two, three, four, five, six, seven, eight, nine, zero, add, sub, mul, div, cancel, equal;
ArrayList<Float> math = new ArrayList<Float>();
float m1;
float m2;
float temp;
int currentOperation = 0;
int nextOperation;
final static int ADD = 1;
final static int SUBTRACT = 2;
final static int MULTIPLY =3;
final static int DIVISION = 4;
final static int EQUALS = 0;
final static int CLEAR = 1;
final static int DONT_CLEAR = 0;
int clearDisplay = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edittest1 = (TextView) findViewById(R.id.edittest1);
one =(Button) findViewById(R.id.btnNum1Id);
two =(Button) findViewById(R.id.btnNum2Id);
three =(Button) findViewById(R.id.btnNum3Id);
four =(Button) findViewById(R.id.btnNum4Id);
five =(Button) findViewById(R.id.btnNum5Id);
six =(Button) findViewById(R.id.btnNum6Id);
seven =(Button) findViewById(R.id.btnNum7Id);
eight =(Button) findViewById(R.id.btnNum8Id);
nine =(Button) findViewById(R.id.btnNum9Id);
zero =(Button) findViewById(R.id.btnNum0Id);
add =(Button) findViewById(R.id.btnNumAddId);
sub =(Button) findViewById(R.id.btnNumSubId);
mul =(Button) findViewById(R.id.btnNumMulId);
div =(Button) findViewById(R.id.btnNumDivId);
cancel =(Button) findViewById(R.id.btnNumClearId);
equal =(Button) findViewById(R.id.btnNumEqualId);
edittest1.setKeyListener(DigitsKeyListener.getInstance(true,true));
registerListeners();
}
private void registerListeners() {
// TODO Auto-generated method stub
one.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("1");
}
});
two.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("2");
}
});
three.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("3");
}
});
four.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("4");
}
});
five.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("5");
}
});
six.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("6");
}
});
seven.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("7");
}
});
eight.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("8");
}
});
nine.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("9");
}
});
zero.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (clearDisplay == CLEAR) {
edittest1.setText("");
}
clearDisplay = DONT_CLEAR;
edittest1.append("0");
}
});
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calcLogic(ADD);
}
}
);
sub.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calcLogic(SUBTRACT);
}
});
mul.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calcLogic(MULTIPLY);
}
});
div.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calcLogic(DIVISION);
}
});
equal.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
calcLogic(EQUALS);
}
});
cancel.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
edittest1.setText("0");
m1 = 0;
m2 = 0;
math.removeAll(math);
currentOperation = 0;
nextOperation = 0;
}
});
}
private void calcLogic(int operator){
math.add(Float.parseFloat(edittest1.getText().toString()));
if (operator != EQUALS) {
nextOperation = operator;
}
else if (operator == EQUALS){
nextOperation = 0;
//operator=' ';
}
switch (currentOperation) {
case ADD:
m1 = math.get(0);
m2 = math.get(1);
math.removeAll(math);
math.add(m1 + m2);
edittest1.setText(String.format("%.3f", math.get(0)));
break;
case SUBTRACT:
m1 = math.get(0);
m2 = math.get(1);
math.removeAll(math);
math.add(m1 - m2);
edittest1.setText(String.format("%.3f", math.get(0)));
break;
case MULTIPLY:
m1 = math.get(0);
m2 = math.get(1);
math.removeAll(math);
math.add(m1 * m2);
edittest1.setText(String.format("%.3f", math.get(0)));
break;
case DIVISION:
m1 = math.get(0);
m2 = math.get(1);
math.removeAll(math);
math.add(m1 / m2);
edittest1.setText(String.format("%.3f", math.get(0)));
break;
}
clearDisplay = CLEAR;
currentOperation = nextOperation;
if (operator == EQUALS) {
m1 = 0;
m2 = 0;
math.removeAll(math);
}
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
package com.example.showoff;
导入java.util.ArrayList;
导入android.os.Bundle;
导入android.app.Activity;
导入android.text.method.DigitsKeyListener;
导入android.view.Menu;
导入android.view.view;
导入android.widget.Button;
导入android.widget.TextView;
公共类MainActivity扩展了活动{
TextView编辑测试1;
按钮一,二,三,四,五,六,七,八,九,零,加,分,多,除,取消,相等;
ArrayList math=新的ArrayList();
浮动m1;
浮动m2;
浮子温度;
int currentOperation=0;
国际下一步行动;
最终静态整数相加=1;
最终静态整数减去=2;
最终静态整数乘=3;
最终静态整数除法=4;
最终静态int等于0;
最终静态int CLEAR=1;
最终静态整数不清除=0;
int clearDisplay=0;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
edittest1=(TextView)findViewById(R.id.edittest1);
一=(按钮)findViewById(R.id.btnNum1Id);
二=(按钮)findViewById(R.id.btnNum2Id);
三=(按钮)findViewById(R.id.btnNum3Id);
四=(按钮)findViewById(R.id.btnNum4Id);
五=(按钮)findViewById(R.id.btnNum5Id);
六=(按钮)findViewById(R.id.btnNum6Id);
seven=(按钮)findviewbyd(R.id.btnNum7Id);
八=(按钮)findViewById(R.id.btnNum8Id);
九=(按钮)findViewById(R.id.btnNum9Id);
零=(按钮)findViewById(R.id.btnNum0Id);
添加=(按钮)findViewById(R.id.btnnumadded);
sub=(按钮)findViewById(R.id.btnNumSubId);
mul=(按钮)findviewbyd(R.id.btnnumulid);
div=(按钮)findviewbyd(R.id.btnNumDivId);
取消=(按钮)findViewById(R.id.btnNumClearId);
相等=(按钮)findViewById(R.id.btnNumEqualId);
edittest1.setKeyListener(DigitKeyListener.getInstance(true,true));
registerListeners();
}
私有无效注册表侦听器(){
//TODO自动生成的方法存根
一个.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“1”);
}
});
setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“2”);
}
});
三个.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“3”);
}
});
setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“4”);
}
});
5.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“5”);
}
});
setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“6”);
}
});
七.setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图v){
如果(清除显示==清除){
edittest1.setText(“”);
}
clearDisplay=不清除;
edittest1.附加(“7”);
}
}