Android Studio无法获得呼叫按钮

Question

The button works when its alone without the WebView but once I add that only the WebView works and clicking the button does nothing.

Here's my MainActivty.java

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    myWebView = (WebView) findViewById(R.id.myWebView);
    WebSettings webSettings = myWebView.getSettings();
    webSettings.setJavaScriptEnabled(true);
    myWebView.loadUrl("http://");

}
Intent intentCall;
public void onClick(View v){
    intentCall.setAction("android.intent.action.CALL");
    intentCall.setData(Uri.parse("tel:"));
    startActivity(intentCall);
    finish();
}}

Here's my Manifest

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="org.yellowribbon.evindrake.yellowribbonv3" >
<uses-permission android:name="android.permission.CALL_PHONE"></uses-permission>
<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>

Activity_Main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
android:paddingBottom="@dimen/activity_vertical_margin"
tools:context="org.yellowribbon.evindrake.yellowribbonv3.MainActivity">

<WebView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true"
    android:id="@+id/myWebView"
    android:layout_alignParentBottom="true" />

<Button
    android:text="@string/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/button"
    android:layout_alignParentBottom="true"
    android:layout_alignParentRight="true"
    android:layout_alignParentEnd="true" />
</RelativeLayout>

Answer 1

将代码添加到activity_main.xml文件中的内部按钮组件中

android:onClick="onClick"

Answer 2

Push-buttons can be pressed, or clicked, by the user to perform an action!

A typical use of a push-button in an activity would be the following: .

public class MyActivity extends Activity {
     protected void onCreate(Bundle icicle) {
         super.onCreate(icicle);
         setContentView(R.layout.content_layout_id);

         final Button button = (Button) findViewById(R.id.button_id);
         button.setOnClickListener(new View.OnClickListener() {
             public void onClick(View v) {
                 // Perform action on click
             }
         });
     }
 }

However, instead of applying an OnClickListener to the button in your activity, you can assign a method to your button in the XML layout, using the android:onClick . _{You are trying to achieve that without this attribute!}

Now, when a user clicks the button, the Android system calls the activity's myClickMethod(View) (that i created) method. In order for this to work, the method must be public and accept a View as its only parameter. For example:

<Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="myClickMethod"
        android:text="button" />

and in code

public void myClickMethod(View view) {
     // Perform action on click after identify the view
 }

Also you are getting a null pointer because of Intent intentCall

use your onClick(View v) like below,

public void onClick(View v) {
    String number = "18002738255";
    Uri call = Uri.parse("tel:" + number);
    Intent surf = new Intent(Intent.ACTION_CALL, call);
    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CALL_PHONE) != PackageManager.PERMISSION_GRANTED) {
        return;
    }
    startActivity(surf);
}