android - 第二个按钮不起作用，但第一个可以

Question

我创建了一个 main.xml，其中有 4 个按钮，然后我创建了 Activity，我在其中为第一个按钮编写了一个 Intent 以打开一个新 Activity 并且它起作用了。但是后来，我想对第二个按钮做同样的事情，但它没有像第一个按钮那样做......我的回答是为什么？为什么我要改变做同样的 Action ？

这是代码..

主.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"

    >

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

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

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

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


</LinearLayout>

主要 Activity .java:

package com.orar;

import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.view.View;
import android.view.View.OnClickListener;

    //implement the OnClickListener interface
    public class MainActivity extends Activity
    implements OnClickListener {
        /** Called when the activity is first created. */
        @Override
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            setContentView(R.layout.main);

            //get the Button reference
            //Button is a subclass of View 
            //buttonClick if from main.xml "@+id/buttonClick"
            View btnClick = findViewById(R.id.button1);
            //set event listener
            btnClick.setOnClickListener(this);
        }

        //override the OnClickListener interface method
        @Override
        public void onClick(View arg0) {
            if(arg0.getId() == R.id.button1){
                //define a new Intent for the second Activity
                Intent intent = new Intent(this,SecondActivity.class);
                //start the second Activity
                this.startActivity(intent);
            }
        }

从这里开始第二个按钮和问题...

        //implement the OnClickListener interface
        public class MainActivity  extends Activity
        implements OnClickListener {
            /** Called when the activity is first created. */
            @Override
            public void onCreate(Bundle savedInstanceState) {
                super.onCreate(savedInstanceState);

                setContentView(R.layout.main);

                //get the Button reference
                //Button is a subclass of View 
                //buttonClick if from main.xml "@+id/buttonClick"
                View btnClick = findViewById(R.id.button2);
                //set event listener
                btnClick.setOnClickListener(this);
            }

            //override the OnClickListener interface method
            @Override
            public void onClick(View arg0) {
                if(arg0.getId() == R.id.button2){
                    //define a new Intent for the second Activity
                    Intent intent2 = new Intent(this,ThirdActivity.class);
                    //start the second Activity
                    this.startActivity(intent2);
                }
            }
        }
    }

第二个 Activity .java:

package com.orar;

import android.app.Activity;
import android.os.Bundle;

public class SecondActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.second);

    }
}

ThirdActivity.java:

package com.orar;

import android.app.Activity;
import android.os.Bundle;

public class ThirdActivity extends Activity {
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.third);

    }
}

第二个.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
<TextView
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:text="This is the second Activity"
/>
</LinearLayout>

第三个.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:layout_height="match_parent">
<TextView
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:text="This is the third Activity"
/>
</LinearLayout>

Answer 1

你有很多问题。首先，你只为你的第一个按钮设置一个点击监听器:

//buttonClick if from main.xml "@+id/buttonClick"
View btnClick = findViewById(R.id.button1);
//set event listener
findViewById(R.id.button1).setOnClickListener(this);

你应该为你的四个按钮做这件事:

findViewById(R.id.button1).setOnClickListener(this);
findViewById(R.id.button2).setOnClickListener(this);
findViewById(R.id.button3).setOnClickListener(this);
findViewById(R.id.button4).setOnClickListener(this);

然后，第二个问题出在您的 onClick 方法上，您仅在单击第一个按钮时才执行操作。如果单击四个按钮之一，您应该执行操作:

@Override
public void onClick(View arg0) {
    // create a general intent
    Intent intent = null;
    // define an intent for all cases
    switch(arg0.getId()){
        case R.id.button1:
            // Setting intent for first button
            intent = new Intent(this,SecondActivity.class);
            break;
        case R.id.button2:
            // Setting intent for second button
            intent = new Intent(this,ThirdActivity.class);
            break;
        case R.id.button3:
            // Setting intent for third button
            intent = new Intent(this,ThirdActivity.class);
            break;
        case R.id.button4:
            // Setting intent for fourth button
            intent = new Intent(this,ThirdActivity.class);
            break;
    }
    // start the Activity selected at the end
    this.startActivity(intent);
}