更改片段中LinearLayout的权重 - Android Studio

Question

（首先我必须说我有一个普通的英语）。 大家好，我试图从LinearLayout改变Fragment的重量。这是我的代码，但在点击片段时它会崩溃。这个想法是，在点击片段时，它会填充移动屏幕，与其他片段相同。

 public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    View v=inflater.inflate(R.layout.fragment_info1, container, false);
    v.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            LinearLayout XX = (LinearLayout) v.findViewById(R.id.LinearInfo1);
            XX.setLayoutParams(new LinearLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT,RelativeLayout.LayoutParams.MATCH_PARENT,0));
        }
    });
    return v;
}

这是错误：

10-10 20:06:54.222 30286-30286/com.example.jhon.myapplication E/AndroidRuntime:
  FATAL EXCEPTION: main: com.example.jhon.myapplication, PID: 30286
      java.lang.NullPointerException: Attempt to invoke virtual method
      'void android.widget.LinearLayout.setLayoutParams(android.view.ViewGroup$LayoutParams)' on a null object reference 
          at com.example.jhon.myapplication.Info1$1.onClick(Info1.java:79) 
          at android.view.View.performClick(View.java:5612)
          at android.view.View$PerformClick.run(View.java:22285)
          at android.os.Handler.handleCallback(Handler.java:751)
          at android.os.Handler.dispatchMessage(Handler.java:95)
          at android.os.Looper.loop(Looper.java:154)
          at android.app.ActivityThread.main(ActivityThread.java:6123)
          at java.lang.reflect.Method.invoke(Native Method)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)

在xml代码中，我尝试将每个片段放在线性布局中，以便能够更轻松地修改它们的重量。

<FrameLayout 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:orientation="vertical"
    tools:context="com.example.jhon.myapplication.Informacion">
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:id="@+id/LinearInfo1">
            <fragment
                android:id="@+id/fragment"
                android:name="com.example.jhon.myapplication.Info1"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                tools:layout="@layout/fragment_info1" />
        </LinearLayout>
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:id="@+id/LinearInfo2"
            android:layout_weight="1">
            <fragment
                android:id="@+id/fragment2"
                android:name="com.example.jhon.myapplication.Info2"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                tools:layout="@layout/fragment_info2" />
        </LinearLayout>
    </LinearLayout>
</FrameLayout>  

新的Logcat信息：

10-10 21:06:03.232 10887-10887/com.example.jhon.myapplication E/AndroidRuntime: FATAL EXCEPTION: main
        Process: com.example.jhon.myapplication, PID: 10887
        java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.LinearLayout.setLayoutParams(android.view.ViewGroup$LayoutParams)' on a null object reference
            at com.example.jhon.myapplication.Info1$1.onClick(Info1.java:80)
            at android.view.View.performClick(View.java:5612)
            at android.view.View$PerformClick.run(View.java:22285)
            at android.os.Handler.handleCallback(Handler.java:751)
            at android.os.Handler.dispatchMessage(Handler.java:95)
            at android.os.Looper.loop(Looper.java:154)
            at android.app.ActivityThread.main(ActivityThread.java:6123)
            at java.lang.reflect.Method.invoke(Native Method)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)

Answer 1

在您的代码中尝试此操作。

private LinearLayout XX;

@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
    View v = inflater.inflate(R.layout.fragment_info1, container, false);
    // add here 
    XX = (LinearLayout) v.findViewById(R.id.LinearInfo1);
    v.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
            param.weight = 1;

            // edited here
            if (XX != null) {
                XX.setLayoutParams(param);
            }
        }
    });
    return v;
}

- 将LinearLayout设为全局变量。

- 使LinearLayout最终

final LinearLayout XX = (LinearLayout) v.findViewById(R.id.LinearInfo1);

  

找到LinearLayout

的相应ID

Answer 2

尝试将LinearLayout置于内部匿名方法之外，并从相对布局参数切换到线性布局参数：

View v = inflater.inflate(R.layout.fragment_info1, container, false);
LinearLayout XX = (LinearLayout) v.findViewById(R.id.LinearInfo1);
v.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        LinearLayout.LayoutParams param = new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, LinearLayout.LayoutParams.MATCH_PARENT);
        param.weight = 1;

        XX.setLayoutParams(param);
    }
});

return v;