按下按钮关闭其他活动并打开新活动：Android Studio

我想通过按下Android Studio上的按钮关闭一个活动，同时打开另一个活动。我尝试了以下方法：

public void MainActivity(View v) {
    Intent intent = new Intent(getApplicationContext(), MainActivity.class);
    startActivity(intent);

    (FirstActivity(MainActivity();)).finish();

}

这段代码是在我的项目中用FirstActivity.java编写的。但不幸的是，这不起作用

还有其他的方法吗？或者我做错了吗

谢谢你的帮助

必要信息：

FirstActivity.java

    package com.ardacebi.libra;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.content.Intent;
import android.net.Uri;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import com.google.android.gms.common.api.GoogleApiClient;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class FirstActivity extends AppCompatActivity {

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



    public void MainActivity(View v) {
        Intent intent = new Intent(getApplicationContext(), MainActivity.class);
        startActivity(intent);



    }



}

    package com.ardacebi.libra;

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;

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();


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

MainActivity.java

    package com.ardacebi.libra;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.content.Intent;
import android.net.Uri;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;

import com.google.android.gms.common.api.GoogleApiClient;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;

public class FirstActivity extends AppCompatActivity {

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



    public void MainActivity(View v) {
        Intent intent = new Intent(getApplicationContext(), MainActivity.class);
        startActivity(intent);



    }



}

    package com.ardacebi.libra;

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;

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();


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

Activity_First.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_first"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.ardacebi.libra.FirstActivity">


    <ImageView
        android:layout_width="200dp"
        android:layout_height="150dp"
        android:src="@drawable/libralogo"
        android:id="@+id/imageView"
        android:layout_above="@+id/textView6"
        android:layout_centerHorizontal="true" />



    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Welcome to Libra"
        android:textSize="25sp"
        android:id="@+id/textView5"
        android:gravity="center"
        android:layout_marginTop="185dp"
        android:layout_alignParentTop="true"
        android:layout_alignParentStart="true" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="The file sharing platform"
        android:textSize="15sp"
        android:id="@+id/textView6"
        android:gravity="center"
        android:layout_below="@+id/textView5"
        android:layout_alignParentStart="true" />

    <TextView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Libra, let's you to share your files over a private, secured network to your friends easily"
        android:textSize="15sp"
        android:id="@+id/textView4"
        android:gravity="center"
        android:layout_marginTop="20dp"
        android:layout_below="@+id/textView6"
        android:layout_alignParentStart="true" />


    <Button
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Start Sharing"
        android:layout_below="@+id/textView4"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="17dp"
        android:id="@+id/button2"
        android:onClick="MainActivity"/>



</RelativeLayout>

注意：当在第一个活动上按下开始共享按钮时，我想将用户发送到主活动。

---

要从第一个活动开始主活动，应如下所示：

public void MainActivity(View v){
    startActivity(new Intent(this, MainActivity.class));
}

Tip1：如果希望用户返回到第一个活动，则无需完成第一个活动，因此如果您完成了我们刚刚创建的主要活动或按下了“后退”按钮，则它将返回到第一个活动，而无需创建新活动

如果要打开主活动并完成第一个活动，只需在启动主活动后添加“finish（）；”，如下所示：

public void MainActivity(View v){
    startActivity(new Intent(this, MainActivity.class));
    finish();
}

Tip2：在这种情况下，您需要开始另一个第一个活动，您不能返回到同一个第一个活动，因为我们已经完成了它

---

希望我的回答对您有用：）

您可以让应用程序记住用户使用以下命令按下了共享按钮：SharedReferences 在第一个活动的public类中，添加这一行，它基本上是首选项的名称：

public static final String PREFS_NAME = "PreferencesFile";

在第一个活动的onCreate方法中添加代码：

//Get the value of the "FirstBun" key.
SharedPreferences Settings = getSharedPreferences(PREFS_NAME, 0);
boolean FirstRun = Settings.getBoolean("FirstRun", true);

if(FirstRun == false){
    startActivity(new Intent(this, MainActivity.class));
    finish();
}

按下共享按钮时，添加此代码：

public void MainActivity(View v){
    //Change the value of "FirstRun" key to 'False' before opening the main activity.
    SharedPreferences Settings = getSharedPreferences(PREFS_NAME, 0);
    SharedPreferences.Editor editor = Settings.edit();
    editor.putBoolean("FirstRun", false);
    editor.apply();

    //Open the main activity.
    startActivity(new Intent(this, MainActivity.class));
    finish();
}

注意：首选项是与应用程序文件一起存储的“xml”文件

---

如果您在Android设备中清除了应用程序的AppInfo中的应用程序数据，“FirstRun”键的值将返回默认值，即“true”。

您可以发布logcat吗？此代码是否在“MainActivity”中类？可以说您有哪些活动，以及您希望此代码如何处理这些活动。@MousaAlfhaily在文章中添加了必要的信息。非常感谢。这有帮助。当心！还有一个问题，Mousa，按下开始共享按钮后，如何更改启动屏幕。所以应用程序可以记住用户已经通过欢迎屏幕并自动启动主要活动？您可以编辑答案并在底部添加额外部分。再次感谢是的，这是可以做到的，我将发布另一个答案，因为该答案需要另一个部分。好的，我将等待答案。给出错误，无法解析SharedReferences和getBoolean。我如何解决这个问题？您必须在应用程序的包名下导入：import android.content.SharedReferences；仍然没有，它给出了相同的错误。我将为您提供一个GitHub存储库链接，稍后您可以看到，我仍在努力。这对你来说是个好主意吗？是的，当然，我会尽力的。