我刚接触安卓开发。我尝试重建一个应用，当您按下按钮时，会显示文本“new text string”。然而，当我运行AVD并选择虚拟设备时，它没有显示。只有我之前测试的应用程序。有人能提供解决方法吗？非常感谢。
我的代码:<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android= "http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:id="@+id/hello_text"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<Button android:id="@+id/trigger"
android:layout_width="100dip" android:layout_height="100dip"
android:text="@string/button1"
android:layout_below="@+id/hello_text"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="111dp" />
</RelativeLayout>
SimpleActivity.java
package com.example.simpleactivityexample;
import android.app.Activity;
import android.os.Bundle;
import android.widget.Toast;
import android.widget.*;
import android.view.View;
public class SimpleActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Toast.makeText(this, "onCreate", Toast.LENGTH_SHORT).show();
Button startButton = (Button) findViewById(R.id.trigger);
startButton.setOnClickListener(new View.OnClickListener()
{
private TextView tv = (TextView) findViewById(R.id.hello_text);
public void onClick(View view)
{
tv.setText("new text string");
}
}
);
}
@Override
protected void onStart() {
super.onStart();
Toast.makeText(this, "onStart", Toast.LENGTH_SHORT).show();
}
@Override
protected void onResume() {
super.onResume();
Toast.makeText(this, "onResume", Toast.LENGTH_SHORT).show();
}
@Override
protected void onRestart() {
super.onRestart();
Toast.makeText(this, "onRestart", Toast.LENGTH_SHORT).show();
}
@Override
protected void onPause() {
Toast.makeText(this, "onPause", Toast.LENGTH_SHORT).show();
super.onPause();
}
@Override
protected void onStop() {
Toast.makeText(this, "onStop", Toast.LENGTH_SHORT).show();
super.onStop();
}
@Override
protected void onDestroy() {
Toast.makeText(this, "onDestroy", Toast.LENGTH_SHORT).show();
super.onDestroy();
}
}
清单文件
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.simpleactivityexample" >
<application
android:debuggable="true"
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.simpleactivityexample.SimpleActivity"
android:configChanges="orientation|keyboardHidden|screenSize"
android:label="@string/app_name"
android:theme="@style/FullscreenTheme" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Strings.xml
<?xml version="1.0" encoding="utf-8"?>
<resources>
<string name="app_name">Dietary Application</string>
<string name="hello">Hello!</string>
<string name="button1">This is a button!</string>
</resources>