我是android应用程序开发的初学者，我试图制作一个基本的计算器应用程序作为我的第一个项目。 XML代码和JAVA代码如下。
在执行三个操作，即减法，乘法和除法时，我无法找到错误。
在减法期间：发生加法。
乘法和除期间：应用程序崩溃。
JAVA代码
package com.example.luci4.basic_calculator;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import java.util.*;
public class MainActivity extends AppCompatActivity {
private Button one;
private Button two;
private Button three;
private Button four;
private Button five;
private Button six;
private Button seven;
private Button eight;
private Button nine;
private Button zero;
private Button add;
private Button sub;
private Button mul;
private Button div;
private Button equals;
private Button clear;
private Button dot;
private TextView text;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
setupUIViews();
zero.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString()+"0");
}
});
one.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "1");
}
});
two.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "2");
}
});
three.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "3");
}
});
four.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "4");
}
});
five.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "5");
}
});
six.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "6");
}
});
seven.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "7");
}
});
eight.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "8");
}
});
nine.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "9");
}
});
add.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "+" );
}
});
sub.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "-" );
}
});
mul.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "*" );
}
});
div.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "/" );
}
});
dot.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
text.setText(text.getText().toString() + "." );
}
});
equals.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
String temp = text.getText().toString();
if(temp!=null){
valueCalculation(temp);
}
}
});
}
private void valueCalculation(String s){
int[] ans = new int[2];
s = s+" ";
String temp="";
char ch = ' ',operator=' ';
for(int i=0;i<s.length();i++){
ch=s.charAt(i);
if(ch=='+'||ch=='-'||ch=='*'||ch=='/'){
ans[0]=Integer.parseInt(temp);
temp="";
operator = ch;
}
if(ch==' '){
ans[1]=Integer.parseInt(temp);
}
temp+=ch;
}
switch(operator){
case '+':
text.setText(Integer.toString(add(ans[0],ans[1])));
break;
case '-':
text.setText(Integer.toString(sub(ans[0],ans[1])));
break;
case '*':
text.setText(Integer.toString(mul(ans[0],ans[1])));
break;
case '/':
text.setText(Integer.toString(div(ans[0],ans[1])));
break;
default:
text.setText("Operation Unavailable");
}
}
private void setupUIViews(){
one = (Button)findViewById(R.id.one);
two = (Button)findViewById(R.id.two);
three = (Button)findViewById(R.id.three);
four = (Button)findViewById(R.id.four);
five = (Button)findViewById(R.id.five);
six = (Button)findViewById(R.id.six);
seven = (Button)findViewById(R.id.seven);
eight = (Button)findViewById(R.id.eight);
nine = (Button)findViewById(R.id.nine);
zero = (Button)findViewById(R.id.zero);
dot = (Button)findViewById(R.id.dot);
add = (Button)findViewById(R.id.add);
sub = (Button)findViewById(R.id.sub);
mul = (Button)findViewById(R.id.mul);
div = (Button)findViewById(R.id.div);
clear = (Button)findViewById(R.id.clear);
equals = (Button)findViewById(R.id.equals);
text = (TextView)findViewById(R.id.text);
}
private int add(int a,int b){
int sum = a+b;
return sum;
}
private int sub(int a,int b){
int dif = a-b;
return dif;
}
private int mul(int a,int b){
int mul = a*b;
return mul;
}
private int div(int a,int b){
int div = a/b;
return div;
}
}
XML代码
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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.luci4.basic_calculator.MainActivity">
<EditText
android:id="@+id/text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignParentTop="true"
android:layout_marginTop="117dp"
android:backgroundTint="@android:color/black"
android:cursorVisible="false"
android:ems="30"
android:inputType="textPersonName"
android:textColor="@android:color/black"
android:textColorHighlight="@android:color/black"
android:textColorLink="@android:color/black"
android:textSize="35sp" />
<Button
android:id="@+id/nine"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignTop="@+id/text"
android:layout_marginTop="89dp"
android:text="9" />
<Button
android:id="@+id/eight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/nine"
android:layout_alignBottom="@+id/nine"
android:layout_marginStart="15dp"
android:layout_toEndOf="@+id/nine"
android:text="8" />
<Button
android:id="@+id/seven"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/eight"
android:layout_alignBottom="@+id/eight"
android:layout_marginStart="15dp"
android:layout_toEndOf="@+id/eight"
android:text="7" />
<Button
android:id="@+id/six"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_below="@+id/nine"
android:layout_marginTop="20dp"
android:text="6" />
<Button
android:id="@+id/five"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/six"
android:layout_alignBottom="@+id/six"
android:layout_alignStart="@+id/eight"
android:text="5" />
<Button
android:id="@+id/four"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/seven"
android:layout_alignTop="@+id/five"
android:text="4" />
<Button
android:id="@+id/three"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignEnd="@+id/six"
android:layout_below="@+id/six"
android:layout_marginTop="20dp"
android:text="3" />
<Button
android:id="@+id/two"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/five"
android:layout_alignTop="@+id/three"
android:text="2" />
<Button
android:id="@+id/one"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/two"
android:layout_alignStart="@+id/four"
android:text="1" />
<Button
android:id="@+id/add"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/seven"
android:layout_alignParentEnd="true"
android:text="+" />
<Button
android:id="@+id/sub"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/four"
android:layout_alignStart="@+id/add"
android:text="-" />
<Button
android:id="@+id/mul"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBaseline="@+id/one"
android:layout_alignBottom="@+id/one"
android:layout_alignParentEnd="true"
android:text="x " />
<Button
android:id="@+id/div"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_below="@+id/mul"
android:layout_marginTop="20dp"
android:text="/" />
<Button
android:id="@+id/zero"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignBottom="@+id/div"
android:layout_alignEnd="@+id/one"
android:text="0" />
<Button
android:id="@+id/dot"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignStart="@+id/two"
android:layout_alignTop="@+id/zero"
android:text="." />
<Button
android:id="@+id/clear"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentStart="true"
android:layout_alignTop="@+id/dot"
android:text="CLEAR" />
<Button
android:id="@+id/equals"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_alignParentEnd="true"
android:text="=" />
</RelativeLayout>
崩溃日志：
07-24 19:35:40.075 4978-4978/? I/art: Late-enabling -Xcheck:jni
07-24 19:35:40.076 4978-4978/? W/art: Unexpected CPU variant for X86 using defaults: x86
07-24 19:35:40.106 4978-4985/? E/art: Failed sending reply to debugger: Broken pipe
07-24 19:35:40.106 4978-4985/? I/art: Debugger is no longer active
07-24 19:35:40.106 4978-4985/? I/art: Starting a blocking GC Instrumentation
07-24 19:35:40.212 4978-4978/? W/System: ClassLoader referenced unknown path: /data/app/com.example.luci4.basic_calculator-2/lib/x86
07-24 19:35:40.222 4978-4978/? I/InstantRun: starting instant run server: is main process
07-24 19:35:40.313 4978-4978/? W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
[ 07-24 19:35:40.532 4978: 4978 D/ ]
HostConnection::get() New Host Connection established 0xd8c9cf20, tid 4978
07-24 19:35:40.823 4978-4994/? D/libEGL: Emulator has host GPU support, qemu.gles is set to 1.
07-24 19:35:40.827 4978-4994/? E/libEGL: load_driver(/system/lib/egl/libGLES_emulation.so): dlopen failed: library "/system/lib/egl/libGLES_emulation.so" not found
07-24 19:35:40.831 4978-4994/? D/libEGL: loaded /system/lib/egl/libEGL_emulation.so
07-24 19:35:40.835 4978-4994/? D/libEGL: loaded /system/lib/egl/libGLESv1_CM_emulation.so
07-24 19:35:40.861 4978-4994/? D/libEGL: loaded /system/lib/egl/libGLESv2_emulation.so
[ 07-24 19:35:40.887 4978: 4994 D/ ]
HostConnection::get() New Host Connection established 0xd8c9d040, tid 4994
07-24 19:35:40.963 4978-4994/? I/OpenGLRenderer: Initialized EGL, version 1.4
07-24 19:35:40.963 4978-4994/? D/OpenGLRenderer: Swap behavior 1
07-24 19:35:41.011 4978-4978/? W/art: Before Android 4.1, method int android.support.v7.widget.ListViewCompat.lookForSelectablePosition(int, boolean) would have incorrectly overridden the package-private method in android.widget.ListView
07-24 19:35:58.229 4978-4978/com.example.luci4.basic_calculator D/AndroidRuntime: Shutting down VM
07-24 19:35:58.229 4978-4978/com.example.luci4.basic_calculator E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.luci4.basic_calculator, PID: 4978
java.lang.NumberFormatException: For input string: "*1"
at java.lang.Integer.parseInt(Integer.java:510)
at java.lang.Integer.parseInt(Integer.java:556)
at com.example.luci4.basic_calculator.MainActivity.valueCalculation(MainActivity.java:169)
at com.example.luci4.basic_calculator.MainActivity.access$100(MainActivity.java:10)
at com.example.luci4.basic_calculator.MainActivity$16.onClick(MainActivity.java:149)
at android.view.View.performClick(View.java:5609)
at android.view.View$PerformClick.run(View.java:22259)
at android.os.Handler.handleCallback(Handler.java:751)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:154)
at android.app.ActivityThread.main(ActivityThread.java:6077)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:865)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:755)
答案 0 :(得分：1)
如@AbhayKoradiya所说
“ * 1”错误。您不能将其转换为整数。
*还添加到临时变量中。那问题。
将else添加到您的结构中应该会有所帮助，因此不会每次执行temp+=ch;：
if(ch=='+'||ch=='-'||ch=='*'||ch=='/'){
ans[0]=Integer.parseInt(temp);
temp="";
operator = ch;
}
else if(ch==' '){ // added here
ans[1]=Integer.parseInt(temp);
}
else{ // and here
temp+=ch;
}
我还没有对此进行测试，所以如果有问题，请提供反馈