Andriod Studio学习笔记第四天

一、单击事件和Toast

1.Button控件处调用onClick方法

<Button
    android:onClick="login"
    android:id="@+id/button"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="8dp"
    android:text="登陆"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintHorizontal_bias="0.189"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:layout_constraintVertical_bias="0.682" />

2.在MainActivity中编写onClick方法

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

import org.w3c.dom.Text;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }

    public void login(View v){
        Toast.makeText(MainActivity.this,"login successfully",Toast.LENGTH_LONG).show();
        //Toast.makeText静态方法，Toast.LENGTH_LONG显示时常
    }
    public void cancel(View v){
        Toast.makeText(MainActivity.this, "cancel successfully", Toast.LENGTH_SHORT).show();
    }
}

3.运行效果

二、新建Activity
1.Activity1

package com.example.wxt.newactivity;

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.TextView;

public class MainActivity extends AppCompatActivity {
    Button button;
    TextView textView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        button=findViewById(R.id.button);
        textView=findViewById(R.id.textView);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent= new Intent(MainActivity.this,Main2Activity.class);
                intent.putExtra("001","today is Feb.2");
                startActivityForResult(intent,0x01);
            }
        });
    }

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if(requestCode==0x01&&resultCode==0x02)
        {
            int i = data.getIntExtra("002",0);
            textView.setText(i+"");
        }
    }
}

2.Activity2

package com.example.wxt.newactivity;

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.TextView;

public class Main2Activity extends AppCompatActivity {
    TextView textView;
    Button button;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        button=findViewById(R.id.button2);
        setContentView(R.layout.activity_main2);
        textView=findViewById(R.id.textView3);
        final Intent intent = getIntent();
        String data = intent.getStringExtra("001");
        textView.setText(data);
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                intent.putExtra("002",888);
                setResult(0x02,intent);
                finish();
            }
        });
    }
}

三、Fragment

布局中左侧为Activity，右侧为Fragment。
左侧Activity中上边为TextView，可以从右侧Fragment返回值，下边为ListView。
右侧Fragment，上边为TextView，下边为Button。

1.设计Fragment布局和编写Fragment类

package com.example.wxt.fragment;

import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class MyFragment extends Fragment {
    @Nullable
    @Override
    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.hh,container,false);
        Button button=view.findViewById(R.id.button);**//Fragment获取自身组件，直接用view**
        button.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                TextView textView = getActivity().findViewById(R.id.textView);**//Fragment获取Activity的组件，用getActivity()**
                textView.setText("来自fragment中的值");
                Toast.makeText(getActivity(),"值已经传完",Toast.LENGTH_LONG).show();
            }
        });
        return view;
    }
}

2.设计左侧Activity，将Fragment和Activity关联起来

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="horizontal"
    tools:context=".MainActivity">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="3"
        android:orientation="vertical">

        <TextView
            android:id="@+id/textView"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="TextView" />

        <ListView
            android:id="@+id/listview1"
            android:layout_width="match_parent"
            android:layout_height="match_parent" />
    </LinearLayout>

    <fragment
        android:id="@+id/fragment1"
        android:name="com.example.wxt.fragment.MyFragment"**//注意这里，将Activity的fragment1与设计的MyFragment相关联。**
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_weight="1"></fragment>
</LinearLayout>

package com.example.wxt.fragment;

import android.support.v4.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {
    ListView listView;
    TextView textView;
    FragmentManager manager;
    ArrayAdapter<String>adapter;
    String[] name={"A","B","C","D"};
    String[] content={"AAA","BBB","CCC","DDD"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        listView = findViewById(R.id.listview1);
        textView=findViewById(R.id.textView);
        adapter=new ArrayAdapter<String>(MainActivity.this,R.layout.item,name);
        listView.setAdapter(adapter);
        manager = getSupportFragmentManager();**//初始化**
        MyFragment myFragment= (MyFragment) manager.findFragmentById(R.id.fragment1);
        final TextView textView1=myFragment.getView().findViewById(R.id.textView2);
        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
            @Override
            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
            textView1.setText(content[position]);
            }
        });

    }
}

item中为左侧Activity属性