Question

我试图在带有导航抽屉菜单的android项目中包含随机数的生成。对于后者，我一直在关注一个youtube教程（Android开发教程＃12 - 生成一个随机数），它完美地工作，但仅限于基本的android工作室项目。作为一个java新手，我试图将相同的Java代码包含在已包含导航抽屉菜单代码的MainActivity.java中时遇到困难。我假设我插入数字生成的相应示例代码的位置（代码段中的第114到126行）必须以某种方式出错，并且我一直在尝试文件中的不同方法。但我总是得到错误：无法访问的声明（在第114行）。 Thx提前提供任何帮助！

package...

import android.app.FragmentManager;
import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.view.View;
import android.support.design.widget.NavigationView;
import android.support.v4.view.GravityCompat;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
import android.widget.TextView;


public class MainActivity extends AppCompatActivity
        implements NavigationView.OnNavigationItemSelectedListener {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);

        FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
        fab.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                        .setAction("Action", null).show();
            }
        });

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
                this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
        drawer.setDrawerListener(toggle);
        toggle.syncState();

        NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
        navigationView.setNavigationItemSelectedListener(this);
    }

    @Override
    public void onBackPressed() {
        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        if (drawer.isDrawerOpen(GravityCompat.START)) {
            drawer.closeDrawer(GravityCompat.START);
        } else {
            super.onBackPressed();
        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    @SuppressWarnings("StatementWithEmptyBody")
    @Override
    public boolean onNavigationItemSelected(MenuItem item) {
        // Handle navigation view item clicks here.
        int id = item.getItemId();
        FragmentManager fragmentManager = getFragmentManager();

        if (id == R.id.nav_first_layer) {
            fragmentManager.beginTransaction()
                    .replace(R.id.content_frame
                            , new FirstFragment())
                    .commit();
        } else if (id == R.id.nav_second_layer) {
            fragmentManager.beginTransaction()
                    .replace(R.id.content_frame
                            , new SecondFragment())
                    .commit();
        } else if (id == R.id.nav_third_layer) {
            fragmentManager.beginTransaction()
                    .replace(R.id.content_frame
                            , new ThirdFragment())
                    .commit();
        } else if (id == R.id.nav_share) {

        } else if (id == R.id.nav_send) {

        }

        DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
        drawer.closeDrawer(GravityCompat.START);
        return true;

        final TextView textOne = (TextView) findViewById(R.id.rndsampletext);

        Button pushMe = (Button) findViewById(R.id.rndsamplebutton);

        final String [] txtOptions = {"One", "Two", "Three"};

        pushMe.setOnClickListener(new View.OnClickListener(){
            @Override
            public void onClick(View v) {
                int rando = (int) (Math.random() * 3);
                textOne.setText(txtOptions[rando]);
            };
        });

    }


}

Answer 1

你在开始时回归真实：

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    drawer.closeDrawer(GravityCompat.START);
    return true;  // here

应该在你生成随机数之后：

我建议您将代码添加到onCreate()

的activity方法中

像：

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

    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG)
                    .setAction("Action", null).show();
        }
    });

    //move this here
    final TextView textOne = (TextView) findViewById(R.id.rndsampletext);

    Button pushMe = (Button) findViewById(R.id.rndsamplebutton);

    final String [] txtOptions = {"One", "Two", "Three"};

    pushMe.setOnClickListener(new View.OnClickListener(){
        @Override
        public void onClick(View v) {
            int rando = (int) (Math.random() * 3);
            textOne.setText(txtOptions[rando]);
        };
    });

    DrawerLayout drawer = (DrawerLayout) findViewById(R.id.drawer_layout);
    ActionBarDrawerToggle toggle = new ActionBarDrawerToggle(
            this, drawer, toolbar, R.string.navigation_drawer_open, R.string.navigation_drawer_close);
    drawer.setDrawerListener(toggle);
    toggle.syncState();

    NavigationView navigationView = (NavigationView) findViewById(R.id.nav_view);
    navigationView.setNavigationItemSelectedListener(this);
}

在Android导航抽屉中正确放置活动代码

1 个答案: