在Android中的三個活動之間切換？

Question

我有三項活動，即一個場景：

1. MainActivity
2. DerivedActivity
3. ThirdPage

我想第一次與導航到第二和第三位。

這裏是我的清單（AndroidManifest.xml中）

<?xml version="1.0" encoding="utf-8"?> 
<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
    package="org.example.implicitexplicit" 
    android:versionCode="1" 
    android:versionName="1.0" > 

    <uses-sdk 
     android:minSdkVersion="14" 
     android:targetSdkVersion="21" /> 

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

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

</manifest> 

現在的主要活動（MainActivity.java）

package org.example.implicitexplicit; 

import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
public class MainActivity extends Activity { 

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

public void impliex(View v) 
{ 
    Intent intent=new Intent(this, DerivedActivity.class); 
    startActivity(intent); 

} 


@Override 
public boolean onCreateOptionsMenu(Menu menu) { 
    // Inflate the menu; this adds items to the action bar if it is present. 
    getMenuInflater().inflate(R.menu.main, menu); 
    return true; 
} 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    // Handle action bar item clicks here. The action bar will 
    // automatically handle clicks on the Home/Up button, so long 
    // as you specify a parent activity in AndroidManifest.xml. 
    int id = item.getItemId(); 
    if (id == R.id.action_settings) { 
     return true; 
    } 
    return super.onOptionsItemSelected(item); 
} 
} 

第二屆（DerivedActivity.java）

package org.example.implicitexplicit; 
import android.app.Activity; 
import android.content.Intent; 
import android.os.Bundle; 
import android.view.MenuItem; 
import android.view.View; 
public class DerivedActivity extends Activity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.derived_activity); 
    getActionBar().setDisplayHomeAsUpEnabled(true); 
} 

private void explicit(View v) { 
     Intent intent = new Intent(this, ThirdPage.class); 
     startActivity(intent); 
    } 

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 

    if (item.getItemId()==android.R.id.home) { 
     finish(); 
    } 
    return super.onOptionsItemSelected(item); 
} 
} 

和最近的活動（ThirdPage.java）

​​

在DerivedActivity.java我得到一個警告

The method explicit(View) from the type DerivedActivity is never used locally 

的XML文件如下

activity_main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
android:layout_width="fill_parent" 
android:layout_height="fill_parent" 
android:gravity="center_horizontal" 
android:orientation="vertical" > 

<TextView 
    android:id="@+id/textView1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/eia" 
    android:textAppearance="?android:attr/textAppearanceLarge" /> 

<ImageView 
    android:id="@+id/imageView1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:src="@drawable/ic_launcher" 
    android:contentDescription="@string/imgalt"/> 

<TextView 
    android:id="@+id/textView2" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/desc" 
    android:textAppearance="?android:attr/textAppearanceMedium" /> 

<Button 
    android:id="@+id/button1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/clickme" 
    android:onClick="impliex"/> 

</LinearLayout> 

derived_activity.xml

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

<TextView 
    android:id="@+id/textView1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/derivedText" 
    android:textAppearance="?android:attr/textAppearanceLarge" /> 

<Button 
    android:id="@+id/button1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/clickme" 
    android:onClick="explicit" 
    /> 

</LinearLayout> 

thirdpage_activity.xml

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

<TextView 
    android:id="@+id/textView1" 
    android:layout_width="wrap_content" 
    android:layout_height="wrap_content" 
    android:text="@string/thirdpageText" 
    android:textAppearance="?android:attr/textAppearanceLarge" /> 

</LinearLayout> 

錯誤：

java.lang.IllegalStateException: Could not find a method explicit(View) in the activity class org.example.implicitexplicit.DerivedActivity for onClick handler on view class android.widget.Button with id 'button1' 

Answer 1

您explicit實現方法具d是private，你必須作出這樣的方法publicprivate到public

public void explicit(View v) { 
    Intent intent = new Intent(this, ThirdPage.class); 
    startActivity(intent); 
} 

Answer 2

變化private void explicit該方法的

public void explicit(View v) { 
     Intent intent = new Intent(this, ThirdPage.class); 
     startActivity(intent); 
    } 

Answer 3

更改訪問modifire但它應該是公開的第一。 秒你的異常顯示該方法的名稱是explicitURl，但實際上它是顯式的（查看）

Answer 4

你宣佈你的方法私人使用，因爲clickListener