Question

我有一个活动，点击2个按钮，进入第二个和第三个活动。第二个活动有2个按钮“返回主要活动”和“点击到第三个活动”。点击“返回主活动按钮”的话不回到主活动画面但是点击“转到第3活动”按钮的话第3活动。有人可以帮我解释为什么我的“返回主活动按钮”不起作用吗？

这是我的代码

main activity
{
package com.example.aditya.activitywithinactivity;
import android.content.Intent;
import android.os.Bundle;
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 android.widget.Button;
import android.view.View.OnClickListener;

import static com.example.aditya.activitywithinactivity.R.id.start;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

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

        Button bttn1 = (Button) findViewById(R.id.button1);
        bttn1.setOnClickListener(MainActivity.this);
        Button bttn2 = (Button) findViewById(R.id.button2);
        bttn2.setOnClickListener(MainActivity.this);
    }
    public void onClick(View v) {
        switch (v.getId()) {

            case R.id.button1: {
                Intent intent = new Intent(MainActivity.this, SecondActivity.class);
                startActivity(intent);
            }
            case R.id.button2: {
                Intent intent1 = new Intent(MainActivity.this, ThirdActivity.class);
                startActivity(intent1);
            }
        }
    }
    @Override
    protected void onNewIntent(Intent intent) {
        super.onNewIntent(intent);
        setContentView(R.layout.activity_main);

    };
}

SecondActivity.java

package com.example.aditya.activitywithinactivity;

import android.content.Intent;
import android.os.Bundle;
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.widget.Button;

public class SecondActivity extends AppCompatActivity implements View.OnClickListener {

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

        Button bttn3 = (Button) findViewById(R.id.button3);
        bttn3.setOnClickListener(SecondActivity.this);
        Button bttn4 = (Button) findViewById(R.id.button4);
        bttn4.setOnClickListener(SecondActivity.this);
    }
    public void onClick(View v) {
        switch (v.getId()) {

            case R.id.button3: {
                Intent intent2 = new Intent(this, MainActivity.class);
                intent2.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
                intent2.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
                startActivity(intent2);
            }
            case R.id.button4: {
                Intent intent3 = new Intent(SecondActivity.this, ThirdActivity.class);
                startActivity(intent3);
            }
        }
    };
}

activity_main.xml中

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <EditText
        android:id="@+id/myText1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="buttonClicked"
        android:text="Click to go to Secondary Activity" />

    <Button
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="buttonClicked"
        android:text="Click to go to Third Activity" />

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Button" />

</LinearLayout>

activity_second

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    <EditText
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/myText2" />
    <Button
        android:id="@+id/button3"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="buttonClicked"
        android:text="Return to Main Activity"/>
    <Button
        android:id="@+id/button4"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="buttonClicked"
        android:text="Click to go to Third Activity"/>

</LinearLayout>

Answer 1

试试这个：

public void onClick(View v) {
    switch (v.getId()) {

        case R.id.button3: {
            Intent intent2 = new Intent(SecondActivity.this, MainActivity.class);

            startActivity(intent2);
            break;
        }
        case R.id.button4: {
            Intent intent3 = new Intent(SecondActivity.this, ThirdActivity.class);
            startActivity(intent3);
           break;
        }
    }
};

Answer 2

您可以在onBackPressed();点击返回MainActivity按钮时调用方法SecondActivity.java，并在break语句中使用switch

     public void onClick(View v) {
            switch (v.getId()) {

                case R.id.button3: 
                      onBackPressed();
                      break;

                case R.id.button4: 
                    Intent intent3 = new Intent(SecondActivity.this, ThirdActivity.class);
                    startActivity(intent3);
                    break;

            }
        };

Answer 3

更改MainActivity

Intent i= new Intent(MainActivity.this, SecondActivity.class);
i.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
startActivity(i);
finish();

Answer 4

两行代码在您的来源中：

intent2.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP | Intent.FLAG_ACTIVITY_SINGLE_TOP);
intent2.addFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);

我想知道你想在两个活动之间做些什么。接下来的两个来源可以做到，但它们是不同的。

    //Source code 1:
   Intent intent2 = new Intent(SecondActivity.this, MainActivity.class);
   startActivity(intent2);

//Source code 2:
onBackPressed(); // or finish();

如果使用源代码1，活动任务将创建另一个MainActivity对象并将其置于任务的顶部。

MainActivity @ obj1 | SecondActivity @ obj1 ==＆gt;

MainActivity @ obj1 | SecondActivity @ obj1 | MainActivity @ OBJ2

如果使用源代码2，活动任务将删除SecondActivity对象，以便MainActivity对象位于顶部。

MainActivity @ obj1 | SecondActivity @ obj1 ==＆gt;

MainActivity @ obj1

Answer 5

交换机中没有 break; 语句。它只是继续下一个案例步骤，因此继续下一个活动。此外，您只需调用 finish（）即可结束当前活动并返回 - 这将更适合您的Backstack。无论如何，在每个案例之后添加 break; 。请查看Oracle tutorial关于切换声明。

Activity中的Android Activity使用Intent

5 个答案: