Question

我想更改按钮点击textView上的文字。活动中可以有多个按钮。主要目的是在按钮单击时更改水果的名称，或者单击任何一个按钮。例如：单击按钮1更改名称，单击按钮2下一个名称，单击按钮3下一个名称，依此类推。我正在尝试如下，但名字没有改变。

主要活动

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 {

    private TextView sentence_etx;
    private Button btn_1,btn_2;
    private String[] names = { "Apple","Mango","Cherry","Banana","Extra"};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sentence_etx = (TextView) findViewById(R.id.etx_sentence);
        btn_1 = (Button) findViewById(R.id.btn_1);
        btn_2 = (Button) findViewById(R.id.btn_2);

        for (int i=0;i<=names.length;i++) {
            work(i);
        }
    }

    private void work(final int i) {
            btn_1.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    sentence_etx.setText(names[i]);
                }
            });

            btn_2.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    sentence_etx.setText(names[i]);
                }
            });
    }
}

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: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.awais.test2.MainActivity">




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

        <TextView
            android:layout_marginTop="50dp"
            android:layout_marginRight="30dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/etx_sentence"
            android:text="Names......" />

        <LinearLayout
            android:gravity="center"
            android:layout_marginTop="100dp"
            android:layout_height="wrap_content"
            android:layout_width="match_parent">


        <Button
            android:layout_height="50dp"
            android:layout_width="50dp"
            android:id="@+id/btn_1"
            android:text="1"/>

        <Button
            android:layout_height="50dp"
            android:layout_width="50dp"
            android:id="@+id/btn_2"
            android:text="2"/>

        <Button
            android:layout_height="50dp"
            android:layout_width="50dp"
            android:id="@+id/btn_3"
            android:text="3"/>

        </LinearLayout>


    </LinearLayout>

</RelativeLayout>

Answer 1

删除for (int i=0;i<=names.length;i++) { work(i); }，因为需要设置一次侦听器

work

所以private void work() {的签名将是

onCreate

并从i

调用一次

将if声明为全局并在设置下一个值时设置public class MainActivity extends AppCompatActivity { private int i=0; // code @Override protected void onCreate(Bundle savedInstanceState) { // code btn_1 = (Button) findViewById(R.id.btn_1); btn_2 = (Button) findViewById(R.id.btn_2); // initialize listener work(); } private void work() { btn_1.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { // check bounds if (++i<names.length) { sentence_etx.setText(names[i]); } // else{ // uncomment to reset the value of i // i=0; // } } }); btn_2.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { if (++i<names.length) { sentence_etx.setText(names[i]); } // else{ // uncomment to reset the value of i // i=0; // } } }); } }条件以避免索引绑定异常

buttons

您的所有listener正在执行相同的工作，因此您只需拥有button并将其应用于所有public class MainActivity extends AppCompatActivity { private TextView sentence_etx; private Button btn_1,btn_2; private String[] names = { "Apple","Mango","Cherry","Banana","Extra"}; private int i=0; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); sentence_etx = (TextView) findViewById(R.id.etx_sentence); btn_1 = (Button) findViewById(R.id.btn_1); btn_2 = (Button) findViewById(R.id.btn_2); // initialize listener btn_1.setOnClickListener(listner); btn_2.setOnClickListener(listner); } OnClickListener listner=new OnClickListener() { @Override public void onClick(View v) { // check bounds if (++i<names.length) { sentence_etx.setText(names[i]); } // else{ // uncomment to reset the value of i // i=0; // } // note you can also add some conditional statement // to check which button is clicked using v.getId(); } }; }个对象，而不是创建单独的匿名侦听器和

link.BuildUrl((SafeDictionary<string>)null)

Answer 2

每次拨打OnClickListener时，您都会重置work按钮。如果您希望它们显示不同的名称，则无法为它们分配相同的OnClickListener（这是您现在所做的）。

您可以做的是更改work的签名以接收Button作为参数，并在该按钮上设置监听器。然后，在onCreate方法中，您可以决定使用哪个按钮

Answer 3

您只需要设置OnClickListener一次

public class MainActivity extends AppCompatActivity {

    private TextView sentence_etx;
    private Button btn_1,btn_2;
    private String[] names = { "Apple","Mango","Cherry","Banana","Extra"};
    private int curIndex = 0;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        sentence_etx = (TextView) findViewById(R.id.etx_sentence);
        btn_1 = (Button) findViewById(R.id.btn_1);
        btn_2 = (Button) findViewById(R.id.btn_2);

        btn_1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (curIndex == names.length - 1) {
                    curIndex = 0;
                }
                sentence_etx.setText(names[curIndex]);
                curIndex++;
            }
        });

        btn_2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (curIndex == names.length - 1) {
                    curIndex = 0;
                }
                sentence_etx.setText(names[curIndex]);
                curIndex++;
            }
        });
    }

}

使用Android中的按钮单击更改textview的文本

3 个答案: