Activity组件

Android的四大组件：Activity,BroadcastReceiver,Service,ContentProvider

(一）Activity

1.效果图：点击开启第二个Activity 显示到第二个页面

    

2.布局: 两个布局

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    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.example.app2.MainActivity"
    android:orientation="vertical">

    <Button
        android:id="@+id/btn_open"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="开启第二个 Activity " />
</LinearLayout>

slayout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">
    <TextView
        android:id="@+id/tv"
        android:textColor="@color/colorAccent"
        android:textSize="30dp"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
    <Button
        android:id="@+id/btn_close"
        android:text="关闭当前Activity"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />

</LinearLayout>

3.注册

<activity android:name=".SActivity"></activity>

 4.

 MainActivity.java

package com.example.app2;

import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {
    private Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button = (Button) findViewById(R.id.btn_open);
        final Intent intent = new Intent(MainActivity.this,SActivity.class);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                intent.putExtra("info","second Activity");
                startActivity(intent);
            }
        });
    }
}

SActivity.java

package com.example.app2;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;

/**
 * Created by Administrator on 2018/5/22.
 */
public class SActivity extends Activity {
    private Button button_close;
    private TextView textView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.slayout);
        textView = (TextView)findViewById(R.id.tv);
        button_close = (Button)findViewById(R.id.btn_close);
        Intent intent = getIntent();
        String info = intent.getStringExtra("info");
        textView.setText(info);
        button_close.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                finish();

            }
        });

    }
}