我正在尝试在Android中的两个类之间传递一个字符串。第一类是“MainActivity”，第二类是“abc”。
这是我的MainActivity代码：
package com.example.passstrings;
import android.support.v7.app.ActionBarActivity;
import android.support.v4.app.Fragment;
import android.content.Intent;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class MainActivity extends ActionBarActivity {
String pass;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pass = "abcabc";
Intent abc = new Intent(this , abc.class);
abc.putExtra("key", pass);
startActivity(abc);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment())
.commit();
}
}
@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);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container, false);
return rootView;
}
}
}
这是我的abc类代码：
package com.example.passstrings;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;
public class abc extends Activity{
TextView tv1;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tv1=(TextView) findViewById(R.id.textView1);
Intent intent = getIntent();
String pass= intent.getExtras().getString("key");
if(pass!= null){
tv1.setText(pass);
}
}
}
这是我的fragment_main.xml代码：
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.passstrings.MainActivity$PlaceholderFragment" >
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/hello_world" />
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@+id/textView2"
android:layout_marginLeft="69dp"
android:layout_marginTop="72dp"
android:layout_toRightOf="@+id/textView2"
android:text="TextView" />
</RelativeLayout>
这是我的LogCat：
04-04 05:34:38.545: I/dalvikvm(734): Could not find method android.content.pm.PackageManager.getActivityLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-04 05:34:38.545: W/dalvikvm(734): VFY: unable to resolve virtual method 320: Landroid/content/pm/PackageManager;.getActivityLogo (Landroid/content/ComponentName;)Landroid/graphics/drawable/Drawable;
04-04 05:34:38.545: D/dalvikvm(734): VFY: replacing opcode 0x6e at 0x008b
04-04 05:34:38.545: I/dalvikvm(734): Could not find method android.content.pm.ApplicationInfo.loadLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-04 05:34:38.545: W/dalvikvm(734): VFY: unable to resolve virtual method 316: Landroid/content/pm/ApplicationInfo;.loadLogo (Landroid/content/pm/PackageManager;)Landroid/graphics/drawable/Drawable;
04-04 05:34:38.545: D/dalvikvm(734): VFY: replacing opcode 0x6e at 0x0099
04-04 05:34:38.555: D/dalvikvm(734): VFY: dead code 0x008e-0092 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-04 05:34:38.555: D/dalvikvm(734): VFY: dead code 0x009c-00a0 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-04 05:34:38.675: D/AndroidRuntime(734): Shutting down VM
04-04 05:34:38.675: W/dalvikvm(734): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-04 05:34:38.685: E/AndroidRuntime(734): FATAL EXCEPTION: main
04-04 05:34:38.685: E/AndroidRuntime(734): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.passstrings/com.example.passstrings.MainActivity}: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.passstrings/com.example.passstrings.abc}; have you declared this activity in your AndroidManifest.xml?
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.os.Handler.dispatchMessage(Handler.java:99)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.os.Looper.loop(Looper.java:123)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-04 05:34:38.685: E/AndroidRuntime(734): at java.lang.reflect.Method.invokeNative(Native Method)
04-04 05:34:38.685: E/AndroidRuntime(734): at java.lang.reflect.Method.invoke(Method.java:521)
04-04 05:34:38.685: E/AndroidRuntime(734): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-04 05:34:38.685: E/AndroidRuntime(734): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-04 05:34:38.685: E/AndroidRuntime(734): at dalvik.system.NativeStart.main(Native Method)
04-04 05:34:38.685: E/AndroidRuntime(734): Caused by: android.content.ActivityNotFoundException: Unable to find explicit activity class {com.example.passstrings/com.example.passstrings.abc}; have you declared this activity in your AndroidManifest.xml?
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1404)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.Instrumentation.execStartActivity(Instrumentation.java:1378)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.Activity.startActivityForResult(Activity.java:2817)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.support.v4.app.FragmentActivity.startActivityForResult(FragmentActivity.java:839)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.Activity.startActivity(Activity.java:2923)
04-04 05:34:38.685: E/AndroidRuntime(734): at com.example.passstrings.MainActivity.onCreate(MainActivity.java:25)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
04-04 05:34:38.685: E/AndroidRuntime(734): ... 11 more
这是我的清单：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.passstrings"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.passstrings.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>
</application>
</manifest>
如果我删除“startActivity（abc）;”应用程序不会崩溃，如果使用try＆amp; catch应用程序不会崩溃但同时它不执行操作。那可能是什么原因呢？并提前感谢
将活动添加到清单后我的LogCat：
04-04 05:47:16.555: I/dalvikvm(883): Could not find method android.content.pm.PackageManager.getActivityLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-04 05:47:16.555: W/dalvikvm(883): VFY: unable to resolve virtual method 320: Landroid/content/pm/PackageManager;.getActivityLogo (Landroid/content/ComponentName;)Landroid/graphics/drawable/Drawable;
04-04 05:47:16.555: D/dalvikvm(883): VFY: replacing opcode 0x6e at 0x008b
04-04 05:47:16.555: I/dalvikvm(883): Could not find method android.content.pm.ApplicationInfo.loadLogo, referenced from method android.support.v7.internal.widget.ActionBarView.<init>
04-04 05:47:16.565: W/dalvikvm(883): VFY: unable to resolve virtual method 316: Landroid/content/pm/ApplicationInfo;.loadLogo (Landroid/content/pm/PackageManager;)Landroid/graphics/drawable/Drawable;
04-04 05:47:16.565: D/dalvikvm(883): VFY: replacing opcode 0x6e at 0x0099
04-04 05:47:16.565: D/dalvikvm(883): VFY: dead code 0x008e-0092 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-04 05:47:16.565: D/dalvikvm(883): VFY: dead code 0x009c-00a0 in Landroid/support/v7/internal/widget/ActionBarView;.<init> (Landroid/content/Context;Landroid/util/AttributeSet;)V
04-04 05:47:16.775: D/AndroidRuntime(883): Shutting down VM
04-04 05:47:16.775: W/dalvikvm(883): threadid=1: thread exiting with uncaught exception (group=0x4001d800)
04-04 05:47:16.786: E/AndroidRuntime(883): FATAL EXCEPTION: main
04-04 05:47:16.786: E/AndroidRuntime(883): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.passstrings/com.example.passstrings.abc}: java.lang.NullPointerException
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2663)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2679)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.ActivityThread.access$2300(ActivityThread.java:125)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2033)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.os.Handler.dispatchMessage(Handler.java:99)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.os.Looper.loop(Looper.java:123)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.ActivityThread.main(ActivityThread.java:4627)
04-04 05:47:16.786: E/AndroidRuntime(883): at java.lang.reflect.Method.invokeNative(Native Method)
04-04 05:47:16.786: E/AndroidRuntime(883): at java.lang.reflect.Method.invoke(Method.java:521)
04-04 05:47:16.786: E/AndroidRuntime(883): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
04-04 05:47:16.786: E/AndroidRuntime(883): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
04-04 05:47:16.786: E/AndroidRuntime(883): at dalvik.system.NativeStart.main(Native Method)
04-04 05:47:16.786: E/AndroidRuntime(883): Caused by: java.lang.NullPointerException
04-04 05:47:16.786: E/AndroidRuntime(883): at com.example.passstrings.abc.onCreate(abc.java:20)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
04-04 05:47:16.786: E/AndroidRuntime(883): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627)
04-04 05:47:16.786: E/AndroidRuntime(883): ... 11 more
和我的清单：
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.passstrings"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.passstrings.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="com.example.passstrings.abc" />
</application>
</manifest>
答案 0 :(得分：5)
您需要将第二个Activity添加到Androidmanifest.xml文件中。
<activity android:name="com.example.passstrings.abc" />
答案 1 :(得分：3)
只是ActivityNotFoundException表示您忘记在AndroidManifest.xml文件中声明abc活动。
只需在应用程序标记的manifest.xml中添加以下行。
<activity android:name="com.example.passstrings.abc" />
对于新的NullPointerException，这里是解决方案
当您在activity_main中声明TextView时，您已在活动文件fragment_main.xml中定义了以下.xml，这就是为什么它会给出NullPointerException。
我建议你从下一行改变xml
setContentView(R.layout.activity_main);
到
setContentView(R.layout.fragment_main.xml);
答案 2 :(得分：3)
have you declared this activity in your AndroidManifest.xml?
04-04 05:34:38.685: E/AndroidRuntime(734): at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1404)
它清楚地说明你没有在清单文件中声明你的abc活动。 have you declared this activity in your AndroidManifest.xml?
所以只需在清单文件中对你的abc活动进行decalre。
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.passstrings.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=".abc"
</activity>
</application>
添加此行
<activity
android:name=".abc"
</activity>
并在你的abc.java
中更改它setContentView(R.layout.activity_main);
你引用activity_main只需要为abc设置abc.XML或你的XML文件名。所以用
setContentView(R.layout.abc);
修改
public class abc extends Activity{
TextView tv1;
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.fragment_main);
tv1=(TextView) findViewById(R.id.textView1);
Intent intent = getIntent();
String pass= intent.getExtras().getString("key");
if(pass!= null){
tv1.setText(pass);
}
}