java - 返回按钮无意中退出应用程序

Question

希望这没有被问到。

在构建应用程序并从主 Activity 成功打开新 Activity 时，按下后退按钮时，应用程序将退出而不是返回到主 Activity。

这是从主 Activity 调用的 Activity 的代码。

package com.austinrhodes.simplesounds;

import android.app.Activity;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.KeyEvent;
import android.view.MenuItem;

public class About extends Activity{

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_about);
}

 public boolean onKeyDown(int keyCode, KeyEvent event) 
 {
    if ((keyCode == KeyEvent.KEYCODE_BACK))
    NavUtils.navigateUpFromSameTask(this);
    finish();
    return true;
 }

@Override
    public boolean onOptionsItemSelected(MenuItem item) {
        switch (item.getItemId()) {
        case android.R.id.home:
            NavUtils.navigateUpFromSameTask(this);
            finish();
            return true;
        }
        return super.onOptionsItemSelected(item);
    }
}

这是主要 Activity

package com.austinrhodes.simplesounds;

import android.os.Bundle;
import android.app.Activity;
import android.app.DialogFragment;
import android.content.Intent;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.widget.LinearLayout;
import android.widget.TextView;

public class Launch extends Activity {

    int size = 3;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //inflate view from XML
        setContentView(R.layout.activity_launch);
        createTvArray();
    }

    private void createTvArray() {
        //create array of text views to be added to main view
        TextView[] tv = new TextView[size];
        //create a temporary text view
        TextView temp; 

        for (int i = 0; i < size; i++) 
        {
            //make a new text view object for each of the alarms
            temp = new TextView(this);
            temp.setText("Alarm: " + i); //arbitrary task
            //get instance of Linear Layout
            LinearLayout myLinearLayout = (LinearLayout) findViewById(R.id.linearAlarm);
            // add the textview to the linearlayout
            myLinearLayout.addView(temp);

            tv[i] = temp;
        }

    }

    private void openSettings(){

        Intent intent = new Intent(this, Settings.class);
        startActivity(intent);      
        finish();

    }

    private void openAbout(){

        Intent intent = new Intent(this, About.class);
        startActivity(intent);      
        finish();

    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.activity_launch, menu);
        return true;
    }

    public boolean onCreateOptionsMenu1(Menu menu) {
        MenuInflater inflater = getMenuInflater();
        inflater.inflate(R.menu.activity_launch, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle item selection
        switch (item.getItemId()) {
            case R.id.settings:
                openSettings();
                return true;
            case R.id.new_alarm:
                DialogFragment newFragment = new AddAlarm();
                newFragment.show(getFragmentManager(), "add_alarm");
                return true;
            case R.id.about:
                openAbout();
                return true;
            default:
                return super.onOptionsItemSelected(item);
        }
    }

}

相关方 xml fragment

<activity android:name="com.austinrhodes.simplesounds.About" >
            <meta-data
            android:name="android.support.PARENT_ACTIVITY"
            android:value="com.austinrhodes.simplesounds.Launch" />
</activity>

Answer 1

试试这个

public boolean onKeyDown(int keyCode, KeyEvent event) {
            switch (keyCode) {
            case KeyEvent.KEYCODE_BACK:
                CurrentClass.this.finish();
                Intent i = new Intent(CurrentClass.this, MainActivity.class);
                startActivity(i);
                return true;
            default:
                return false;
            }