Question

我做了一个基本的android程序作为写作练习。但是无论何时打开它都会崩溃。我在手机上尝试过，但遗憾的是我的android工作室模拟器不能在我的电脑上工作，所以我的调试能力不是很多。它构建正常，所以我猜它不是语法错误或其他东西。

AndroidManifest.xml：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.net.crackerjacksystems.talkies">

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity android:name=".MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

activity_main.xml中：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:theme="@style/AppTheme"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">
<Button
    android:id="@+id/Zero"
    android:layout_width="260dp"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:text="@string/Button0"
    android:textSize="40sp"/>
<Button
    android:id="@+id/One"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@id/Zero"
    android:text="@string/Button1"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Two"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@id/Zero"
    android:layout_toRightOf="@+id/One"
    android:layout_toEndOf="@+id/One"
    android:text="@string/Button2"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Three"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@id/Zero"
    android:layout_toRightOf="@+id/One"
    android:layout_toEndOf="@+id/Two"
    android:text="@string/Button3"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Four"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/One"
    android:text="@string/Button4"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Five"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/One"
    android:layout_toRightOf="@id/Four"
    android:layout_toEndOf="@id/Four"
    android:text="@string/Button5"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Six"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/One"
    android:layout_toRightOf="@id/Five"
    android:layout_toEndOf="@id/Five"
    android:text="@string/Button6"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Seven"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Four"
    android:text="@string/Button7"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Eight"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Five"
    android:layout_toRightOf="@id/Seven"
    android:layout_toEndOf="@id/Seven"
    android:text="@string/Button8"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Nine"
    android:layout_width="130dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Six"
    android:layout_toRightOf="@id/Eight"
    android:layout_toEndOf="@id/Eight"
    android:text="@string/Button9"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Add"
    android:layout_width="96dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Seven"
    android:text="@string/ButtonAdd"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Subtract"
    android:layout_width="96dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Eight"
    android:layout_toRightOf="@id/Add"
    android:layout_toEndOf="@id/Add"
    android:text="@string/ButtonSubtract"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Multiply"
    android:layout_width="96dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Eight"
    android:layout_toRightOf="@id/Subtract"
    android:layout_toEndOf="@id/Subtract"
    android:text="@string/ButtonMultiply"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Divide"
    android:layout_width="98dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Eight"
    android:layout_toRightOf="@id/Multiply"
    android:layout_toEndOf="@id/Multiply"
    android:text="@string/ButtonDivide"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Clear"
    android:layout_width="192dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Add"
    android:text="@string/ButtonClear"
    android:textSize="40sp"/>
<Button
    android:id="@+id/AllClear"
    android:layout_width="192dp"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Add"
    android:layout_toRightOf="@id/Clear"
    android:layout_toEndOf="@id/Clear"
    android:text="@string/ButtonAllClear"
    android:textSize="40sp"/>
<Button
    android:id="@+id/Equals"
    android:layout_width="192dp"
    android:layout_height="wrap_content"
    android:layout_toRightOf="@id/Zero"
    android:layout_toEndOf="@id/Zero"
    android:layout_alignParentBottom="true"
    android:text="@string/ButtonEqual"
    android:textSize="40sp"/>
<TextView
    android:id="@+id/Screen"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_above="@+id/Clear"
    android:textSize="82sp"
    />
</RelativeLayout>

MainActivity.java：

package com.net.crackerjacksystems.talkies;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.view.View.OnClickListener;
import android.widget.TextView;

public class MainActivity extends Activity {
int first = 0, second = 0;
boolean onFirst = true;
char op;
Button zero = (Button)findViewById(R.id.Zero);
Button one = (Button)findViewById(R.id.One);
Button two = (Button)findViewById(R.id.Two);
Button three = (Button)findViewById(R.id.Three);
Button four = (Button)findViewById(R.id.Four);
Button five = (Button)findViewById(R.id.Five);
Button six = (Button)findViewById(R.id.Six);
Button seven = (Button)findViewById(R.id.Seven);
Button eight = (Button)findViewById(R.id.Eight);
Button nine = (Button)findViewById(R.id.Nine);
Button add = (Button)findViewById(R.id.Add);
Button sub = (Button)findViewById(R.id.Subtract);
Button mul = (Button)findViewById(R.id.Multiply);
Button div = (Button)findViewById(R.id.Divide);
Button cl = (Button)findViewById(R.id.Clear);
Button acl = (Button)findViewById(R.id.AllClear);
Button eql = (Button)findViewById(R.id.Equals);
TextView screen = (TextView)findViewById(R.id.Screen);
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    main();
}
void main(){
    screen.setText(first);
    zero.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10);screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    one.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+1;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    two.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+2;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    three.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+3;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    four.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+4;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    five.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+5;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    six.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+6;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    seven.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+7;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    eight.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+8;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    nine.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(onFirst){first = (first*10)+9;screen.setText(first);}
            else{second = (second*10);screen.setText(second);}
        }
    });
    add.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            screen.setText(null);
            op = '+';
            onFirst = false;
        }
    });
    sub.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            screen.setText(null);
            op = '-';
            onFirst = false;
        }
    });
    mul.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            screen.setText(null);
            op = '*';
            onFirst = false;
        }
    });
    div.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            screen.setText(null);
            op = '/';
            onFirst = false;
        }
    });
    cl.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            screen.setText(null);
            if(onFirst){first = 0;}
            else{second = 0;}
        }
    });
    acl.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            screen.setText(null);
            first = 0;
            second = 0;
        }
    });
    eql.setOnClickListener(new OnClickListener() {
        @Override
        public void onClick(View v) {
            if(op == '+'){screen.setText(first+second);}
            if(op == '-'){screen.setText(first-second);}
            if(op == '*'){screen.setText(String.valueOf(first*second));}
            if(op == '/'){screen.setText(String.valueOf(first/second));}
        }
    });
}
}

的strings.xml：

<resources>
<string name="app_name">Calculator</string>
<string name="Button1">1</string>
<string name="Button2">2</string>
<string name="Button3">3</string>
<string name="Button4">4</string>
<string name="Button5">5</string>
<string name="Button6">6</string>
<string name="Button7">7</string>
<string name="Button8">8</string>
<string name="Button9">9</string>
<string name="Button0">0</string>
<string name="ButtonAdd">+</string>
<string name="ButtonSubtract">—</string>
<string name="ButtonMultiply">✕</string>
<string name="ButtonDivide">÷</string>
<string name="ButtonClear">C</string>
<string name="ButtonAllClear">AC</string>
<string name="ButtonEqual">=</string>
</resources>

只是为了澄清，它是一个非常简单的计算器。
如果有人可以帮助解决为什么会崩溃，那会很好。

Answer 1

将findViewById()所有来电转移到onCreate()内，因为它无法找到＆＃34;＆＃34;在致电setContentView()之前。

private Button zero, one, two, three, four, five, six, seven, eight, nine, add, sub, mul, div, cl, acl, eql;
private TextView screen;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    zero = (Button)findViewById(R.id.Zero);
    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);
    add = (Button)findViewById(R.id.Add);
    sub = (Button)findViewById(R.id.Subtract);
    mul = (Button)findViewById(R.id.Multiply);
    div = (Button)findViewById(R.id.Divide);
    cl = (Button)findViewById(R.id.Clear);
    acl = (Button)findViewById(R.id.AllClear);
    eql = (Button)findViewById(R.id.Equals);
    screen = (TextView)findViewById(R.id.Screen);

    main();
}

Android计算器程序崩溃

1 个答案: