java - 无法找到或启动 Activity Intent

Question

我有一个应用程序，它有一个计数器并将其存储到数据库中。我试图通过创建 View 布局类和 View 按钮来检查查询语句是否正常工作。但是，当我单击“查看”按钮时，它强制关闭，并且日志猫说没有找到任何 Activity 。我检查以确保它在 list 中，并确保它的拼写和大写正确。

    package com.example.testdatabase;

import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

public class MainActivity extends Activity {

int counter;
Button add;
Button sub;
Button save;
Button view;
TextView display;
private SharedPreferences prefs;
private String prefName = "MyPref";
MySQLiteHelper db = new MySQLiteHelper(this);


public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    counter = 0;
    add = (Button) findViewById(R.id.button1);
    sub = (Button) findViewById(R.id.button2);
    save = (Button) findViewById(R.id.button3);
    view = (Button) findViewById(R.id.button4);
    display = (TextView) findViewById(R.id.tvDisplay);
    add.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            counter++;
            display.setText("Counter: " + counter);
        }
    });
    sub.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub
            counter--;
            display.setText("Counter: " + counter);
        }
    });

    save.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            db.add(counter);

        }
    });

    view.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            Intent i = new Intent("com.example.testdatabase.Sqlview");
            startActivity(i);

        }
    });

}

protected void onPause()
{
    super.onPause();

    prefs = getSharedPreferences(prefName, MODE_PRIVATE);
    SharedPreferences.Editor edit = prefs.edit();

    edit.putInt("counter", counter);
    edit.commit();

}

protected void onResume()
{
    super.onResume();

    prefs = getSharedPreferences(prefName, MODE_PRIVATE);

    counter = prefs.getInt("counter", counter);
    display.setText("Counter: " + counter);


}

}

查看类

    package com.example.testdatabase;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class Sqlview extends Activity {

protected void onCreate(Bundle savedInstanceState )
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.sqlview);
    TextView tv = (TextView) findViewById(R.id.textView1);
    MySQLiteHelper info = new MySQLiteHelper(this);
    String data = info.getData();

    tv.setText(data);



}

}

list

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

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="18" />



<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.example.testdatabase.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.testdatabase.Sqlview"
        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>

日志猫

    11-17 17:29:15.394: E/AndroidRuntime(279): FATAL EXCEPTION: main
    11-17 17:29:15.394: E/AndroidRuntime(279): android.content.ActivityNotFoundException: No Activity found to handle Intent { act=com.example.testdatabase.Sqlview }
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.app.Instrumentation.checkStartActivityResult(Instrumentation.java:1408)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.app.Instrumentation.execStartActivity(Instrumentation.java:1378)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.app.Activity.startActivityForResult(Activity.java:2817)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.app.Activity.startActivity(Activity.java:2923)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at com.example.testdatabase.MainActivity$4.onClick(MainActivity.java:71)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.view.View.performClick(View.java:2408)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.view.View$PerformClick.run(View.java:8816)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.os.Handler.handleCallback(Handler.java:587)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.os.Handler.dispatchMessage(Handler.java:92)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.os.Looper.loop(Looper.java:123)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at android.app.ActivityThread.main(ActivityThread.java:4627)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at java.lang.reflect.Method.invokeNative(Native Method)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at java.lang.reflect.Method.invoke(Method.java:521)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:868)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:626)
    11-17 17:29:15.394: E/AndroidRuntime(279):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

您为 Intent 使用了错误的构造函数。应该是:

view.setOnClickListener(new View.OnClickListener() {    
        @Override
        public void onClick(View v) {
            // TODO Auto-generated method stub

            Intent i = new Intent(MainActivity.this, Sqlview.class);
            startActivity(i);

        }
});