0

我正在创建一个模拟滚动不同类型骰子的应用程序。所有的骰子都是通过一个充满按钮的 AlertDialog 来选择的。我想为其中六个按钮使用一个 OnClickListener，但是当我尝试设置该侦听器时，eclipse 会抛出 NullPointerException。

    package edu.elon.cs.diceroller;


import android.app.Activity;
import android.app.AlertDialog;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ListView;
import android.widget.TextView;


public class RollMenuActivity extends Activity {

    private int diceAmount;
    private int diceSides;
    private boolean sum;

    private Button addDiceButton;
    private Button rollDiceButton;
    private ListView diceListView;

    private Button oneButton;
    private Button twoButton;
    private Button threeButton;
    private Button fourButton;
    private Button fiveButton;
    private Button sixButton;

    private Button d4;
    private Button d6;
    private Button d8;
    private Button d12;
    private Button d20;

    private Button sumButton;
    private Button top3Button;
    private Button trimButton;
    private Button avgButton;
    private Button hiLoButton;
    private Button loHiButton;

    private TextView displayQuantity;
    private TextView displayType;
    private TextView displayArrange;

    private OnClickListener addDiceListener = new OnClickListener() {

        @Override
        public void onClick(View aArg0) {

            AlertDialog.Builder alert = new AlertDialog.Builder(
                    RollMenuActivity.this);
            LayoutInflater factory = LayoutInflater
                    .from(RollMenuActivity.this);
            View layout = factory.inflate(R.layout.dice_select, null);
            alert.setView(layout);


            alert.show();

        }
    };
    private OnClickListener rollDiceListener = new OnClickListener() {

        @Override
        public void onClick(View aV) {
            // TODO Auto-generated method stub

        }

    };

    @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_roll_menu, menu);
        return true;
    }

    private OnClickListener quantityListener = new OnClickListener(){

        @Override
        public void onClick(View v) {
            Button aButton = (Button) v;
            String buttonNumber = aButton.getText().toString();
            diceAmount = Integer.parseInt(buttonNumber.trim());
            displayQuantity.setText(buttonNumber);

        }

    };

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

        addDiceButton = (Button) findViewById(R.id.adddicebutton);
        rollDiceButton = (Button) findViewById(R.id.rolldicebutton);
        diceListView = (ListView) findViewById(R.id.dicelistview);

        addDiceButton.setOnClickListener(addDiceListener);
        rollDiceButton.setOnClickListener(rollDiceListener);

        oneButton = (Button) findViewById(R.id.button1);
        twoButton = (Button) findViewById(R.id.button2);
        threeButton = (Button) findViewById(R.id.button3);
        fourButton = (Button) findViewById(R.id.button4);
        fiveButton = (Button) findViewById(R.id.button5);
        sixButton = (Button) findViewById(R.id.button6);

        oneButton.setOnClickListener(quantityListener);
        twoButton.setOnClickListener(quantityListener);
        threeButton.setOnClickListener(quantityListener);
        fourButton.setOnClickListener(quantityListener);
        fiveButton.setOnClickListener(quantityListener);
        sixButton.setOnClickListener(quantityListener);


        displayQuantity = (TextView) findViewById(R.id.displayquantity);

    }
}


<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".RollMenuActivity" >

    <ListView
        android:id="@+id/dicelistview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/adddicebutton" >

    </ListView>

    <Button
        android:id="@+id/rolldicebutton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="Press or Shake to Roll Dice"
        tools:ignore="HardcodedText" />

    <Button
        android:id="@+id/adddicebutton"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/rolldicebutton"
        android:layout_alignParentLeft="true"
        android:text="Add a Dice"
        tools:ignore="HardcodedText" />

</RelativeLayout>

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/diceselectlayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:id="@+id/linearLayout2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="34dp" >

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="1" />

        <Button
            android:id="@+id/buttond4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="d4" />

        <Button
            android:id="@+id/buttonsum"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" Sum " />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout5"
        android:layout_centerHorizontal="true" >

        <Button
            android:id="@+id/button5"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="5" />

        <Button
            android:id="@+id/buttond20"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="d20" />

        <Button
            android:id="@+id/buttonhilo"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Hi-Lo" />
    </LinearLayout>

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_centerHorizontal="true"
        android:text="Type"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/linearLayout2"
        android:layout_alignParentTop="true"
        android:text="Quantity"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/textView3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentTop="true"
        android:layout_alignRight="@+id/linearLayout2"
        android:text="Arrange"
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <LinearLayout
        android:id="@+id/linearLayout3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/linearLayout2"
        android:layout_below="@+id/linearLayout2" >

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="2" />

        <Button
            android:id="@+id/buttond6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="d6" />

        <Button
            android:id="@+id/buttontop3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Top 3" />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/linearLayout3"
        android:layout_below="@+id/linearLayout3" >

        <Button
            android:id="@+id/button3"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="3" />

        <Button
            android:id="@+id/buttond8"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="d8" />

        <Button
            android:id="@+id/buttontrim"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Trim " />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout5"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/linearLayout4"
        android:layout_below="@+id/linearLayout4" >

        <Button
            android:id="@+id/button4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="4" />

        <Button
            android:id="@+id/buttond12"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="d12" />

        <Button
            android:id="@+id/buttonavg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text=" Avg. " />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/linearLayout6"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout1"
        android:layout_centerHorizontal="true" >

        <Button
            android:id="@+id/button6"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="6" />

        <Button
            android:id="@+id/button17"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="  " />

        <Button
            android:id="@+id/buttonlohi"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Lo-Hi" />
    </LinearLayout>

    <TextView
        android:id="@+id/displayquantity"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignLeft="@+id/linearLayout5"
        android:layout_below="@+id/linearLayout6"
        android:layout_marginTop="17dp"
        android:text=" "
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/displaytype"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/textView4"
        android:layout_centerHorizontal="true"
        android:text=" "
        android:textAppearance="?android:attr/textAppearanceMedium" />

    <TextView
        android:id="@+id/displayarrange"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBaseline="@+id/textView5"
        android:layout_alignBottom="@+id/textView5"
        android:layout_alignRight="@+id/linearLayout2"
        android:text=" "
        android:textAppearance="?android:attr/textAppearanceMedium" />

</RelativeLayout>
4

1 回答 1

0

不要创建保存OnClickListener实现实例的变量，而是使用实现OnClickListener和覆盖该OnClick方法的类。

在onCreate将对象的新实例分配给按钮期间

使用 Android SDK 在创建过程中实例化对象onCreate而不是依赖类在创建过程中实例化它们是更好的做法。

编辑：我也修复了Integer.parseInteger你的方法。如果无法解析，则会抛出异常。

// Create Classes that implement OnClickListener

private class OnAddDiceListener implements OnClickListener
{
    public void onClick(View v)
    {
        LayoutInflater inflater = LayoutInflater.from(v.getContext());

        View layout = inflater.inflate(R.layout.dice_select, null);

        Builder builder = new Builder(v.getContext());
        builder.setView(layout);

        AlertDialog alert = builder.create();
        alert.show();
    }
}

private class OnRollDiceListener implements OnClickListener
{
    public void onClick(View v)
    {

    }
}

private class OnQuantityListener implements OnClickListener
{
    public void onClick(View v)
    {
        Button button = (Button) v;

        try
        {
            diceAmount = Integer.parseInt(button.getText().toString());
        }
        catch(NumberFormatException e)
        {
            diceAmount = 0;
            e.printStackTrace();
        }

        displayQuantity.setText(diceAmount);
    }
}

@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_roll_menu, menu);
    return true;
}

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);

    setContentView(R.layout.activity_roll_menu);

    addDiceButton = (Button) findViewById(R.id.adddicebutton);
    rollDiceButton = (Button) findViewById(R.id.rolldicebutton);
    diceListView = (ListView) findViewById(R.id.dicelistview);

    // Since this is the onCreate method, instantiate the Listeners for the buttons
    addDiceButton.setOnClickListener(new OnAddDiceListener());
    rollDiceButton.setOnClickListener(new OnRollDiceListener());

    oneButton = (Button) findViewById(R.id.button1);
    twoButton = (Button) findViewById(R.id.button2);
    threeButton = (Button) findViewById(R.id.button3);
    fourButton = (Button) findViewById(R.id.button4);
    fiveButton = (Button) findViewById(R.id.button5);
    sixButton = (Button) findViewById(R.id.button6);

    // Instantiate the OnQuantityListener
    oneButton.setOnClickListener(new OnQuantityListener());
    twoButton.setOnClickListener(new OnQuantityListener());
    threeButton.setOnClickListener(new OnQuantityListener());
    fourButton.setOnClickListener(new OnQuantityListener());
    fiveButton.setOnClickListener(new OnQuantityListener());
    sixButton.setOnClickListener(new OnQuantityListener());

    displayQuantity = (TextView) findViewById(R.id.displayquantity);
}
于 2013-05-19T15:30:58.793 回答