Question

我有一项活动让我遇到了问题。

问题在于，当我进入活动时，我无法回到之前的状态活动，除非我按下后退按钮5次。

活动是通过列表输入的，此列表还有其他一些具有相同问题的活动。请注意，并非所有人都有一样的问题。

这是我的Java代码：

package com.exple.v1;

import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class MoviesMaingenreActivity extends ActionBarActivity {

    LayoutInflater inflater;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        populateListView();
        registerClickCallback();

    }
    private void registerClickCallback() {

        ListView list = (ListView)findViewById(R.id.listView1);

        list.setOnItemClickListener(new AdapterView.OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {

                Intent intent;
                switch(position)
                {

                case 1:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieActionGenreActivity.class);
                    startActivity(intent);
                    break;
                case 2:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieAnimationGenreActivity.class);
                    startActivity(intent);
                    break;
                case 3:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieComedyGenreActivity.class);
                    startActivity(intent);
                    finish();
                case 4:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieDocumentaryGenreActivity.class);
                    startActivity(intent);
                case 5:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieHorrorGenreActivity.class);
                    startActivity(intent);
                case 6:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieDramaGenreActivity.class);
                    startActivity(intent);
                case 7:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieScifiGenreActivity.class);
                    startActivity(intent);
                    break;
                default:
                    break;
                }
            }
        });

    }

    private void populateListView() {



        String[] textz = {"Action","Animation","Komedi","Dokumentär","Skräck","Drama","Sci-fi"};
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,R.layout.the_list, textz);
        ListView listView = (ListView)findViewById(R.id.listView1);
        listView.setAdapter(adapter);

        inflater = (LayoutInflater)this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View header = inflater.inflate(R.layout.header_movies_maingenres,null);
        listView.addHeaderView(header,null,false);



    }

}

从案例3到案例7确实会出现问题。

为什么这样做？

Answer 1

您需要在案例编号3,4,5和6中使用break

                case 3:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieComedyGenreActivity.class);
                    startActivity(intent);
                    finish();
                    break; // this is what is missing here...
                case 4:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieDocumentaryGenreActivity.class);
                    startActivity(intent);
                    break; // this is what is missing here...
                case 5:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieHorrorGenreActivity.class);
                    startActivity(intent);
                    break; // this is what is missing here...
                case 6:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieDramaGenreActivity.class);
                    startActivity(intent);
                    break; // this is what is missing here...

Answer 2

你的问题是你没有打破这个案子，所以意图它在那里遇到了很多麻烦：

case 3:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieComedyGenreActivity.class);
                    startActivity(intent);
                    finish(); 
 //break; missing
                case 4:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieDocumentaryGenreActivity.class);
                    startActivity(intent);
//break; missing

                case 5:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieHorrorGenreActivity.class);
                    startActivity(intent);
//break; missing
                case 6:
                    intent = new Intent(MoviesMaingenreActivity.this,MovieDramaGenreActivity.class);
                    startActivity(intent);
//break; missing

Answer 3

您需要在每个案例后包含一个break语句。基本上如果3为真，则执行3到7. break语句阻止它在循环中执行代码。 case语句只是告诉它从哪里开始执行代码

如果多次按下后退按钮，活动将无法返回

3 个答案: