ContentView更改后按钮不起作用

Question

感谢您花时间与我一起调查我的问题。我是Android开发的新手，这是我第一次尝试应用程序。任何和所有的帮助将不胜感激。此时所有建议都是必要的建议。

手头的主要问题是btnBack和btnSubmit没有触发onClick事件。请指教。

helloformstuff.java

package com.uDrew.helloformstuff;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.Spinner;
public class helloformstuff extends Activity implements OnClickListener {

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    Log.i("DrewDebug", "Loading: layout.main");

    setContentView(R.layout.main);

    Log.i("DrewDebug", "Loaded: layout.main");

    Log.i("DrewDebug", "Loading: Drunk Spinner");

    //Drunk Spinner
    Spinner spLevel = (Spinner) findViewById(R.id.spLevel);
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
            this, R.array.drunk_array, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spLevel.setAdapter(adapter);

    Log.i("DrewDebug", "Loaded: Drunk Spinner");

    Log.i("DrewDebug", "Listening for Buttons");
    //Listen for button clicks
    Button btnNext = (Button) this.findViewById(R.id.btnNext);
    Button btnSubmit = (Button) this.findViewById(R.id.btnSubmit);
    Button btnBack = (Button) this.findViewById(R.id.btnBack);

    if (btnNext!= null) {
        //If btnNext was hit
        btnNext.setOnClickListener(new OnClickListener() {

            public void onClick(View v) {

            Log.i("DrewDebug", "Button Hit: Next");
            //Log the beginning of this code 
            Log.i("DrewDebug", "BEGIN Next Code");

            //Change to second Screen
            setContentView(R.layout.second);

            //Initialize State Spinner
            Spinner spState = (Spinner) findViewById(R.id.spState);
            ArrayAdapter<CharSequence> adapter2 = ArrayAdapter.createFromResource(
                    helloformstuff.this, R.array.state_array, android.R.layout.simple_spinner_item);
            adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
            spState.setAdapter(adapter2);

          //Log the end of the this code
            Log.i("DrewDebug", "END Next Code");
            }
        });
    }

    if (btnBack != null) {
        //If btnBack was hit
        btnBack.setOnClickListener(new OnClickListener() {
            public void onClick(View v){
                Log.i("DrewDebug", "Button Hit: Back");
                //Log the beginning of this code 
                Log.i("DrewDebug", "BEGIN Back Code");
                //Change to first screen
                setContentView(R.layout.main);

                //Drunk Spinner
                Spinner spLevel = (Spinner) findViewById(R.id.spLevel);
                ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
                        helloformstuff.this, R.array.drunk_array, android.R.layout.simple_spinner_item);
                adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
                spLevel.setAdapter(adapter);

                //Log the end of the this code
                Log.i("DrewDebug", "END Back Code");
            }
        });
    }
}
}

main.xml中

<EditText 
    android:id="@+id/txtQuote" 
    android:layout_width="match_parent"
    android:layout_height="wrap_content" 
    android:text="Enter Quote" /> 

<TextView 
    android:id="@+id/lblWho" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content"
    android:layout_below="@id/txtQuote"
    android:text="Who Said It?"/>

<EditText 
    android:id="@+id/txtFirst" 
    android:layout_width="250px"
    android:layout_height="wrap_content" 
    android:layout_below="@id/lblWho"
    android:layout_alignParentLeft="true"
    android:layout_marginRight="10dip"
    android:text="Anonymous" />

<EditText 
    android:id="@+id/txtLast" 
    android:layout_width="50px"
    android:layout_height="wrap_content"
    android:layout_toRightOf="@id/txtFirst"
    android:layout_alignTop="@id/txtFirst"
    android:text="X"/>

<Spinner 
    android:id="@+id/spLevel"
    android:prompt="@string/drunk_prompt" 
    android:layout_width="match_parent"
    android:layout_height="wrap_content" 
    android:layout_below="@id/txtFirst"
    android:layout_alignParentLeft="true"/>

<Button 
    android:id="@+id/btnNext" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:layout_below="@id/spLevel"
    android:layout_alignParentRight="true"
    android:text="Next"/>

second.xml

<TextView 
    android:id="@+id/lblShare" 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content"
    android:text="Who's Sharing?"/>

<EditText 
    android:id="@+id/txtFirstShare" 
    android:layout_width="250px"
    android:layout_height="wrap_content" 
    android:layout_below="@id/lblShare"
    android:layout_alignParentLeft="true"
    android:layout_marginRight="10dip"
    android:text="Anonymous" />

<EditText 
    android:id="@+id/txtLastShare" 
    android:layout_width="50px"
    android:layout_height="wrap_content"
    android:layout_toRightOf="@id/txtFirstShare"
    android:layout_alignTop="@id/txtFirstShare"
    android:text="X"/>

<EditText 
    android:id="@+id/txtCity" 
    android:layout_width="250px"
    android:layout_height="wrap_content"
    android:layout_below="@id/txtLastShare"
    android:layout_alignParentLeft="true"
    android:layout_marginRight="10dip"
    android:text="NoWhere"/>

<Spinner 
    android:id="@+id/spState"
    android:prompt="@string/state_prompt" 
    android:layout_width="match_parent"
    android:layout_height="wrap_content" 
    android:layout_toRightOf="@id/txtCity"
    android:layout_alignTop="@id/txtCity"/>

<Button 
    android:id="@+id/btnSubmit" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:layout_below="@id/spState"
    android:layout_alignParentRight="true"
    android:text="Submit"/>

<Button 
    android:id="@+id/btnBack" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content"
    android:layout_toLeftOf="@id/btnSubmit"
    android:layout_alignParentLeft="true"
    android:layout_alignTop="@id/btnSubmit"
    android:text="Back"/>

string.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Random Drunk Quotes</string>
<string name="drunk_prompt">Level of Buzz</string>
<string-array name="drunk_array">
    <item>One Beer Syndrome</item>
    <item>Buzzed</item>
    <item>Drunk</item>
    <item>Trashed</item>
    <item>Retarded</item>
</string-array>

<string name="state_prompt">State</string>
<string-array name="state_array">
                  <item>AL</item> 
                  <item>AK</item> 
                  <item>AS</item> 
                  <item>AZ</item> 
                  <item>AR</item> 
                  <item>CA</item> 
                  <item>CO</item> 
                  <item>CT</item> 
                  <item>DE</item> 
                  <item>DC</item> 
                  <item>FM</item> 
                  <item>FL</item> 
                  <item>GA</item> 
                  <item>GU</item> 
                  <item>HI</item> 
                  <item>ID</item> 
                  <item>IL</item> 
                  <item>IN</item> 
                  <item>IA</item> 
                  <item>KS</item> 
                  <item>KY</item> 
                  <item>LA</item> 
                  <item>ME</item> 
                  <item>MH</item> 
                  <item>MD</item> 
                  <item>MA</item> 
                  <item>MI</item> 
                  <item>MN</item> 
                  <item>MS</item> 
                  <item>MO</item> 
                  <item>MT</item> 
                  <item>NE</item> 
                  <item>NH</item> 
                  <item>NV</item> 
                  <item>NJ</item> 
                  <item>NM</item> 
                  <item>NY</item> 
                  <item>NC</item> 
                  <item>ND</item> 
                  <item>MP</item> 
                  <item>OH</item> 
                  <item>OK</item> 
                  <item>OR</item> 
                  <item>PW</item> 
                  <item>PA</item> 
                  <item>PR</item> 
                  <item>RI</item> 
                  <item>SC</item> 
                  <item>SD</item> 
                  <item>TN</item> 
                  <item>TX</item> 
                  <item>UT</item> 
                  <item>VT</item> 
                  <item>VI</item> 
                  <item>VA</item> 
                  <item>WA</item> 
                  <item>WV</item> 
                  <item>WI</item> 
                  <item>WY</item> 
</string-array>

新来源：

    //Listen for btnNext button click
    Button btnNext = (Button) this.findViewById(R.id.btnNext);
    Button btnBack = (Button) this.findViewById(R.id.btnBack);
    Button btnSubmit = (Button) this.findViewById(R.id.btnSubmit);

    if (btnNext!= null) {
        btnNext.setOnClickListener(new OnClickListener() {
            public void onClick(View v) {

                clickNext();
            }
        });
    }
    if (btnBack != null) {
        //If btnBack was hit
        btnBack.setOnClickListener(new OnClickListener() {
            public void onClick(View v){
                clickBack();
            }
        });
    }
    if (btnSubmit != null) {
        //If btnSubmit was hit
        btnSubmit.setOnClickListener(new OnClickListener() {
            public void onClick(View v){
                clickSubmit();
            }
        });
    }
}



public void clickNext(){
    //Change to second Screen
    setContentView(R.layout.second);

    //Initialize State Spinner
    Spinner spState = (Spinner) findViewById(R.id.spState);
    ArrayAdapter<CharSequence> adapter2 = ArrayAdapter.createFromResource(
            RandomDrunkQuotes.this, R.array.state_array, android.R.layout.simple_spinner_item);
    adapter2.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spState.setAdapter(adapter2);

    Button btnBack = (Button) findViewById(R.id.btnBack);
    btnBack.setOnClickListener(new OnClickListener() {
        public void onClick(View v){
            clickBack();
        }
    });
}
public void clickBack(){
    //Change to first screen
    setContentView(R.layout.main);

    //Drunk Spinner
    Spinner spLevel = (Spinner) findViewById(R.id.spLevel);
    ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(
            RandomDrunkQuotes.this, R.array.drunk_array, android.R.layout.simple_spinner_item);
    adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
    spLevel.setAdapter(adapter);

    Button btnNext = (Button) findViewById(R.id.btnNext);
    Button btnSubmit = (Button) findViewById(R.id.btnSubmit);
    btnNext.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {

            clickNext();
        }
    });
}
public void clickSubmit(){

}

Answer 1

问题是，由于你的onClick监听器改变了布局，他们自己也需要为新布局设置处理程序。您最好在Activity中创建新的私有方法来设置处理程序，然后在onCreate和处理程序中调用该方法。

Answer 2

View仅在布局xml膨胀时创建。你正在膨胀R.layout.main：这只会创建btnNext按钮，因此设置了一个监听器，但是btnBack和btnSubmit按钮上没有设置监听器，因为它们是onCreate方法中的null（因为它们尚不存在）。

一个快速解决方法是在致电btnBack后立即将setOnClickListener setContentView(R.layout.second);移至。

Answer 3

您的内容视图（main.xml）不包含btnBack和btnSubmit的定义。您的代码应如下所示：

Button btnNext = (Button) this.findViewById(R.id.btnNext);
if (btnNext!= null) {
    btnNext.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            ...

            //Change to second Screen
            setContentView(R.layout.second);

            //Initialize State Spinner
            ...
            Button btnBack = (Button) this.findViewById(R.id.btnBack);
            if (btnBack != null) {
                //If btnBack was hit
                btnBack.setOnClickListener(new OnClickListener() {
                    public void onClick(View v){
                        ...
                    }
                });
            }
            Button btnSubmit = (Button) this.findViewById(R.id.btnSubmit);
            if (btnSubmit != null) {
                //If btnSubmit was hit
                btnSubmit.setOnClickListener(new OnClickListener() {
                    public void onClick(View v){
                        ...
                    }
                });
            }
        }
    });
}