问题描述
我是新手的机器人。在Android中我试图运行一个简单的工作。从我的main.xml(http://pastebin.com/Mhgmpj4w)我有一个按钮(我main.java(http://pastebin.com/b5irLVTc)),它会切换到另一个活动second.xml(HTTP: //pastebin.com/F92VxSEZ)它会显示一些文字(我second.java(http://pastebin.com/MR3L5WXL)),但也有一些错误(http://pastebin.com/KH2wDh7b)。我是新手,请帮我。
的main.xml
< XML版本=1.0编码=UTF-8&GT?;
< LinearLayout中的xmlns:机器人=http://schemas.android.com/apk/res/android
机器人:layout_width =FILL_PARENT
机器人:layout_height =FILL_PARENT
机器人:方向=垂直>
<按钮
机器人:ID =@ + ID /按钮1
机器人:layout_width =WRAP_CONTENT
机器人:layout_height =WRAP_CONTENT
机器人:文本=按钮/>
< / LinearLayout中>
main.java:
包com.rana.activities;
进口android.app.Activity;
进口android.content.Intent;
进口android.os.Bundle;
进口android.view.View;
进口android.view.View.OnClickListener;
进口android.widget.Button;
公共类主要扩展活动{
/ **第一次创建活动时调用。 * /
@覆盖
公共无效的onCreate(包savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.main);
按钮B =(按钮)findViewById(android.R.id.button1);
b.setOnClickListener(新OnClickListener(){
公共无效的onClick(视图v){
startActivity(新意图(Main.this,Second.class));
}
});
}
}
second.xml:
< XML版本=1.0编码=UTF-8&GT?;
< LinearLayout中的xmlns:机器人=http://schemas.android.com/apk/res/android
机器人:layout_width =match_parent
机器人:layout_height =match_parent
机器人:方向=垂直>
<的TextView
机器人:ID =@ + ID / textView1
机器人:layout_width =WRAP_CONTENT
机器人:layout_height =WRAP_CONTENT
机器人:文本=这是第二次活动/>
< / LinearLayout中>
second.java:
包com.rana.activities;
进口android.app.Activity;
进口android.os.Bundle;
公共类第二延伸活动{
@覆盖
保护无效的onCreate(包savedInstanceState){
// TODO自动生成方法存根
super.onCreate(savedInstanceState);
的setContentView(R.layout.second);
}
}
logcat的:
10-29 19:19:25.377:D / AndroidRuntime(859):关闭虚拟机
10-29 19:19:25.377:W / dalvikvm(859):主题ID = 1:螺纹退出与未捕获的异常(组= 0x40015560)
10-29 19:19:25.397:E / AndroidRuntime(859):致命异常:主要
10-29 19:19:25.397:E / AndroidRuntime(859):java.lang.RuntimeException的:无法启动的活动ComponentInfo {com.rana.activities / com.rana.activities.Main}:显示java.lang.NullPointerException
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.ActivityThread.access $ 1500(ActivityThread.java:117)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.ActivityThread $ H.handleMessage(ActivityThread.java:931)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.os.Handler.dispatchMessage(Handler.java:99)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.os.Looper.loop(Looper.java:123)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.ActivityThread.main(ActivityThread.java:3683)
10-29 19:19:25.397:E / AndroidRuntime(859):在java.lang.reflect.Method.invokeNative(本机方法)
10-29 19:19:25.397:E / AndroidRuntime(859):在java.lang.reflect.Method.invoke(Method.java:507)
10-29 19:19:25.397:E / AndroidRuntime(859):在com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:839)
10-29 19:19:25.397:E / AndroidRuntime(859):在com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-29 19:19:25.397:E / AndroidRuntime(859):在dalvik.system.NativeStart.main(本机方法)
10-29 19:19:25.397:E / AndroidRuntime(859):由:显示java.lang.NullPointerException
10-29 19:19:25.397:E / AndroidRuntime(859):在com.rana.activities.Main.onCreate(Main.java:18)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-29 19:19:25.397:E / AndroidRuntime(859):在android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
10-29 19:19:25.397:E / AndroidRuntime(859):11 ...更多
< ------- LogCat中------------------->
替换 android.R.id.button1
这与 R.id。按钮1
和导入自己的包研究
类 main.java
。这将解决这个问题。通过这种方式,将所分配的内存,从您的应用程序,因此它不会搜索全球resouces
I am newbie in android. In android I trying to run a simple work. From my main.xml(http://pastebin.com/Mhgmpj4w) I have one button( my main.java(http://pastebin.com/b5irLVTc) ) it will switch to another activity the second.xml(http://pastebin.com/F92VxSEZ) where it will show some text ( my second.java(http://pastebin.com/MR3L5WXL) ) but there are some errors(http://pastebin.com/KH2wDh7b). I am a newbie please help me.
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<Button
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />
</LinearLayout>
main.java:
package com.rana.activities;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class Main extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button b = (Button) findViewById(android.R.id.button1);
b.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
startActivity(new Intent(Main.this, Second.class));
}
});
}
}
second.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="This is the second activity" />
</LinearLayout>
second.java:
package com.rana.activities;
import android.app.Activity;
import android.os.Bundle;
public class Second extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.second);
}
}
logcat:
10-29 19:19:25.377: D/AndroidRuntime(859): Shutting down VM
10-29 19:19:25.377: W/dalvikvm(859): threadid=1: thread exiting with uncaught exception (group=0x40015560)
10-29 19:19:25.397: E/AndroidRuntime(859): FATAL EXCEPTION: main
10-29 19:19:25.397: E/AndroidRuntime(859): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.rana.activities/com.rana.activities.Main}: java.lang.NullPointerException
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.ActivityThread.access$1500(ActivityThread.java:117)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.os.Handler.dispatchMessage(Handler.java:99)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.os.Looper.loop(Looper.java:123)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.ActivityThread.main(ActivityThread.java:3683)
10-29 19:19:25.397: E/AndroidRuntime(859): at java.lang.reflect.Method.invokeNative(Native Method)
10-29 19:19:25.397: E/AndroidRuntime(859): at java.lang.reflect.Method.invoke(Method.java:507)
10-29 19:19:25.397: E/AndroidRuntime(859): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
10-29 19:19:25.397: E/AndroidRuntime(859): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
10-29 19:19:25.397: E/AndroidRuntime(859): at dalvik.system.NativeStart.main(Native Method)
10-29 19:19:25.397: E/AndroidRuntime(859): Caused by: java.lang.NullPointerException
10-29 19:19:25.397: E/AndroidRuntime(859): at com.rana.activities.Main.onCreate(Main.java:18)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
10-29 19:19:25.397: E/AndroidRuntime(859): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)
10-29 19:19:25.397: E/AndroidRuntime(859): ... 11 more
<-------LogCat------------------->
Replace android.R.id.button1
this with R.id.button1
and import your own package R
class in main.java
. It will solve the problem. In this way it will allocated the memory from your application and hence it will not search for the global resouces
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