我目前正在尝试开发一个从一个页面切换到另一个页面的简单功能,但每次启动应用程序时都会崩溃。
activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Screen One......"
android:textAppearance="?android:attr/textAppearanceLarge" />
<Button
android:id="@+id/scan"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Click me to another screen" />
</LinearLayout>
MainActivity.java
package com.example.mdpmk1;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.widget.Button;
import android.view.View;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
Button button;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
addListenerOnButton();
}
public void addListenerOnButton() {
final Context context = this;
button = (Button) findViewById(R.id.scan);
button.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View arg0) {
Intent intent = new Intent(context, ScanScreen.class);
startActivity(intent);
}
});
}
}
ScanScreen.java
package com.example.mdpmk1;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Button;
public class ScanScreen extends Activity {
Button button;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.scan_screen);
}
}
scan_screen.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<TextView
android:id="@+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="You have done it!!"
android:textAppearance="?android:attr/textAppearanceLarge" />
</LinearLayout>
我对这种东西很新,但我正在为我的专业在学校做一个应用程序,并希望它实际工作。任何帮助都很可爱。感谢
答案 0 :(得分:0)
在您的MainActivity onCreate中,您需要添加
setContentView(R.layout.activity_main);
答案 1 :(得分:0)
尝试将类MainActivity中的intent语句编辑为:
Intent intent = new Intent(MainActivity.this, ScanScreen.class);
startActivity(intent);
您还必须添加:
setContentView(R.layout.activity_main);
在ActivityMain类onCreate函数中设置视图。
答案 2 :(得分:0)
setContentView(R.your_layout)
在您的MainActivity的onCreate()中不存在。尝试为您的活动提供布局。
答案 3 :(得分:0)
您忘了在MainActivity的onCreate()方法中写下以下声明,
setContentView(R.layout.activity_main);
写在这里,
public class MainActivity extends Activity
{
Button button;
@Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main); // You forgot this line
addListenerOnButton();
}
还要更改以下代码行,
public void onClick(View arg0)
{
Intent intent = new Intent( MainActivity.this, ScanScreen.class ); // Change here
startActivity(intent);
}
答案 4 :(得分:0)
首先,在MainActivity.OnCreate方法中添加SetContentView(R.layout.activity_main)以调用addListenerOnButton。 然后确保在manifest.xml中添加活动条目并将MainActivity作为主应用程序活动,如下所示:
<activity android:name=".MainActivity">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<activity android:name=".ScanScreen"/>